Aortic knob diameter in chest radiographs of healthy adults in Uganda.

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Steven Magera, Senai Goitom Sereke, Emmy Okello, Faith Ameda, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-944105/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 01 Mar, 2022 Read the published version in Reports in Medical Imaging → Version 1 posted You are reading this latest preprint version Abstract Background The burden of cardiovascular diseases, such as aortic and degenerative diseases grows in the aging population. Chest radiograph still plays an important role in the diagnosis of cardiovascular diseases. Aortic knob diameter in chest radiographs can be used to evaluate early changes of the aortic structure and together with clinical and laboratory findings. This study was aimed at determining the mean values of aortic knob diameter among healthy adults in Uganda. Methods We conducted a descriptive cross-sectional study in three selected hospitals in Kampala Uganda. All participants had normal chest radiographs without radiological evidence of cardiovascular disease. Chest radiograph findings extracted included aortic knob diameter, aortic arch diameter, transverse heart diameter and transverse thoracic diameter. All films were independently examined by two experienced radiologists. Results We analyzed chest radiograph findings of 294 participants, of which 204 (69.4%) were male. Aortic knob diameter increased with age (p – 0.000). The mean aortic knob diameter of males was higher than for females (3.14±0.34cm versus 2.77±0.37cm, p – 0.000). The mean aortic knob diameter on the digital screen were higher than plain films (3.03±0.393cm versus 2.96±0.392cm, p – 0.000). Aortic knob diameter positively correlated with age (p – 0.000) and aortic arch diameter (p – 0.000). Aortic knob diameter also correlated positively with transverse thoracic diameter (p – 0.05), transverse heart diameter (p – 0.05) and cardiothoracic ratios (p – 0.05). Conclusion The aortic knob diameter was higher in males and there was a positive correlation with age, aortic arch diameter, transverse heart diameter and transverse thoracic diameter. Aortic knob diameter measurements should be done on digital screen than printed x ray films. Nuclear Medicine & Medical Imaging Aortic knob diameter chest radiograph cardiovascular Uganda Figures Figure 1 Background Cardiovascular disease accounts for three quarters of all global estimated deaths in the low- and middle-income countries ( 1 ). Chest radiograph remains an important tool for investigation of cardiovascular conditions despite the advent of newer and more sophisticated imaging modalities such as echocardiography, computerized tomography (CT) and magnetic resonance imaging (MRI) in the world ( 2 ). This is mainly due to more readily available and comparatively cheaper costs of performing chest radiograph and still provides valuable clues to diagnosis of cardiovascular pathology ( 3 ). The aorta is a major vascular supply of the human body and also plays an important role in the control of systemic vascular resistance and heart rate. This control is done via pressure-responsive receptors located in the ascending aorta and aortic arch ( 4 ). An increase and decrease in aortic pressure results in a decrease of heart rate and systemic vascular resistance, and an increase of heart rate and systemic vascular resistance respectively ( 5 ). The Aortic knob is an important structure that refers to the hump-shaped contour of the aorta seen in a frontal chest radiograph on the left mediastinal silhouette ( 6 ). Abnormal aortic knuckle shape, enlargement and aortic nipple, may give the first clue of cardiovascular disease ( 7 ). The aortic knob can be enlarged due to increased pressure flow in aorta, increased volume or changes in the elasticity of its wall. In adults, aortic knob enlargement can be seen in systemic hypertension, valvular insufficiency, aortic dissection, traumatic aortic injury, thoracic aortic aneurysm, and atherosclerosis ( 8 ). Aortic knob diameter (AKD) has been shown to be a good predictor of target organ damage with a sensitivity ranging between 70–90% for different cardiovascular conditions, even in early disease ( 9 ). These include hypertensive heart disease, sub clinical atherosclerosis, aneurysms and aortic dissection ( 10 ). Moreover, aortic knob width is positively correlated with both systolic and diastolic blood pressures ( 10 – 12 ). Uganda is a low income country and yet is experiencing a shift in major causes of death with coronary artery disease and other forms of heart failure on the rise ( 13 ). And the normal AKD in the literature were taken from studies done among Caucasians, Americans, South Koreans, Indians and West Africans. These studies showed that variations exist amongst different populations, age groups and between sexes ( 14 ). In this study therefore, we sought to determine the normal AKD amongst healthy adults in Ugandan. Methods Study design and setting This was a descriptive cross-sectional study conducted in three selected tertiary hospitals – CASE hospital, St Francis Hospital and Kiruddu Hospital – Kampala, Uganda from January 2020 to June 2020. St. Francis Hospital is located on Nsambya hill in Makindye Division, one of the five administrative divisions of the city. It lies approximately 5 kilometers southeast of the central business district of Kampala. It is a tertiary referral hospital with a capacity of 361 beds and approximately 450 chest radiographs are performed per month. Kiruddu General Hospital, is in the neighborhood of Kiruddu, on Buziga Hill, in Makindye Division, one of the five administrative units of the Kampala capital city authority. It is approximately 13 kilometers, by road, south-east of the Mulago national referral hospital. Chest radiographs are performed as part of ongoing recruitment in government agencies like police, army and local governments. Case hospital is an urban, private, tertiary hospital in Kampala, Uganda. It is located at 67 - 71 Buganda Road, on Nakasero hill. Around 100 chest radiographs are performed per a month. Study population Study participants included asymptomatic participants referred for chest radiograph examination for the purpose of pre-employment and pre-travel medical check-ups and were recruited in this study. Participants with normal chest radiograph (Posterior anterior view, erect), and age between 18-90 years, with no thoracic skeletal deformity, no known cardio-vascular disease, and normal blood pressure for age (blood pressure chart) were included in the study. Participants whose chest radiographs had significant rotation (>0.5cm) or artifacts were excluded from the study. Sample size A sample size of 294 participants was used using the formula proposed by Rosner B. 2015 as summarized below. N = (Z α/2 +Z β ) 2 *2*σ 2 / d 2 Where N = sample size required. Z α/2 =is the critical value of the Normal distribution at α/2 (e.g. for a confidence level of 95%, α is 0.05 and the critical value is 1.96), Z β =is the critical value of the Normal distribution at β (e.g. for a power of 80%, β is 0.2 and the critical value is 0.84), σ 2 = is the population variance, d = desired level of precision/marginal error ( 1 ). N = (1.96+0.84) 2 *2*(4.1) 2 / ( 1 ) 2 . N=264. Non-response of 10% was 30. Hence the sample size was 294. Study Procedure Study participants who gave their consent were physically examined and enrolled into the study. A total of 294 participants’ postero-anterior (PA) chest radiographs were obtained. The PA chest radiograph of all the candidates were taken in the erect position with a film focus distance of 1.8m. The exposures were made at normal arrested inspiration. Participant’s name, sex, age, height and medical history were recorded. Normal chest radiograph was confirmed by two independent radiologists. Parameters such as AKD, transverse thoracic diameter (TTD) and transverse heart diameter (THD) were evaluated for each patient (figure 1 ). The aortic knob diameter was measured as the maximum transverse diameter from the lateral border of the air in the trachea to the lateral border of the aortic knob ( 15 ). The Aortic arch diameter (AAD) was measured as the most lateral extension to the right and left of the midline at the level of the aortic knob. TTD was measured as the maximum horizontal distance between the internal margins of the chest wall at the level of the right hemi diaphragm ( 16 , 17 ). THD was measured as the sum of the maximum projection to the right and left heart borders from midline ( 16 , 17 ). Data analysis A structured data collection tool was used to collect bio-demographics and relevant history (Appendix 1). Data was analyzed using STATA version 16. Descriptive statistics for continuous variables were presented as mean and standard deviation. Spear man rank correlation was used to test for the correlation between the aortic diameter measurements with continuous independent variables. In addition, Student t test was performed to test for the mean difference of AKD between groups. A p < 0.05 was considered statistically significant. Results A total of 294 participants, of whom 204(69.4%) were male and the age range between 18-89 years were recruited in the study. Overall, 196 (66.7%) participants were attending the hospital for pre-employment medical exam, 92 (31.3%) came for annual medical checkup exams, and 6 (2%) pre travel exams. The mean age of the participants was 35.3±10.5. (Table 1 ). Table 1 Age distribution of the participants Age category Female (f, %) Male (f, %) Total (f, %) 18-29years 40(39.6) 61(60.4) 101(34.4) 30-39years 27(29.4) 65(70.6) 92(31.3) 40-49years 15(20.6) 58(79.4) 73(24.8) 50-59years 7(28.0) 18(72.0) 25(8.5) ≥60 years 1(33.3) 2(66.7) 3(1.0) Total 90(30.6) 204(69.4) 294(100) Male participants had significantly higher mean AKD compared to their female counterparts (3.14±0.34cm versus 2.77±0.37cm, p - 0.000). Those in the age group of 50-59years had significantly higher means than younger people in the age group of 18-29 years (Table 2 and Table 3 ). Table 2 The mean aortic knob diameter of 294 participants. Variables Frequency n=294 Mean ± SD /cm P-value Gender Male 204 3.14±0.34 0.000 Female 90 2.77±0.37 Age category 18-29years 101 2.76±0.34 0.000 30-39years 92 3.01±0.30 40-49years 73 3.26±0.33 50-59years 25 3.43±0.30 ≥60 years 3 3.34±0.56 Table 3 Comparison of aortic knob diameter in males and females by age. Males Females Age/yrs. Mean/cm SD P- value Age/yrs. Mean/cm SD P-value 18-29 2.93 0.28 0.0000 18-29 2.30 0.22 0.0000 30-39 3.07 0.29 30-39 2.86 0.25 40-49 3.32 0.32 40-49 3.05 0.32 50-59 3.46 0.27 50-59 3.34 0.37 ≥60 3.50 0.69 ≥60 3.02 0.00 Men have higher mean aortic knob diameters among all age groups compared to the females. The mean AKD was higher when measurement was done on a digital screen than on the chest radiograph film (3.03±0.393cm versus 2.96±0.392cm, p - 0.000). However, the males still had significantly higher AKD compared to female and unit increase in age would also increase the AKD (Table 5 ). Table 5 The aortic knob diameter measurement on digital screen and x-ray by gender and age groups of 294 participants. Variables n=294 aortic knob diameter digital screen Mean ± SD /mm P-value aortic knob diameter x ray film Mean ± SD /mm P value Aortic knob diameter 294 3.03±0.393 2.96±0.392 0.000 Gender Male 204 3.14±0.34 0.000 3.08±0.37 0.000 Female 90 2.77±0.37 2.70±0.37 Age category 18-29years 101 2.76±0.34 0.000 2.71±0.24 0.000 30-39years 92 3.01±0.30 2.92±0.27 40-49years 73 3.26±0.33 3.20±0.37 50-59years 25 3.43±0.30 3.39±0.47 ≥60 years 3 3.34±0.56 3.67±0.58 The average AKD of the sample population was 3.03±0.39cm, the smallest was 2.2cm and the largest was 4.1 cm. The mean AAD of the study population was 5.63±0.64cm and average cardiothoracic ratio is 0.446±0.037 with highest being 0.522cm and lowest 0.366cm (Table 6 ). Table 6 Other cardiovascular parameters on chest x-ray for 294 participants Variables (unit measures) N Mean ± SD Minimum Maximum Aortic knob diameter (cm) 294 3.03±0.39 2.2 4.1 Aortic arch diameter (cm) 294 5.63±0.64 4.11 7.63 Transvers heart diameter (cm) 294 12.97±1.26 10.03 16.43 Transverse thoracic diameter (cm) 294 29.07±2.78 27.4 36.89 Cardiothoracic ratio 294 0.446±0.037 0.366 0.522 AKD was strongly and more positively correlated with age among the females than in males, the coefficient was higher among the females and the relationship was statistically significant at 95% confidence level r=0.7411 p-value 0.000 for females vs. r=0.5191 p-value 0.000 for males. Strong positive correlation was also observed between the AKD and AAD for both male and female. However, AKD was weakly correlated with THD, TTD and cardiothoracic ratio respectively (Table 7 ). Table 7: Correlation of the aortic knob diameter with Aortic arch diameter, transverse diameter of the chest and heart diameter for male and female population. (Spearman correlation) Variables Correlation coefficient ( r ) for male P-value Correlation coefficient ( r ) for female P-value Age (years) 0.5191 0.05 0.7411 0.05 Aortic arch diameter /cm 0.6136 0.05 0.6518 0.05 Transverse Heart diameter /cm 0.4879 0.05 0.4869 0.05 Transverse thoracic diameter /cm 0.2007 0.05 0.4555 0.05 Cardiothoracic ratio 0.3433 0.05 0.1914 0.05 Weight and height were weakly correlated though positively associated with the aortic knob diameter across both genders. However, it was all higher among the female counterpart and the relationships were not statistically significant at 95% confidence level. Discussion This study sought to determine the aortic knob diameter in chest radiographs of healthy adults in Uganda. The results of our study showed that AKD increases with age in both sexes. This can be explained by geometric and functional alterations seen with aging ( 18 , 19 ). Studies in India, Nigeria, Zambia, United States and South Korea also showed similar results ( 10 , 11 , 20 – 22 ). AKD was higher in males than in females. Among males, the mean average diameter of aortic knob was 3.14±0.34cm. Population based large cohort study in Netherlands showed that men had higher mean thoracic aorta diameter than women but provided no explanation as to why ( 23 ). Mean AKD findings in Indian population ( 20 ) and South Korean population ( 11 ) were comparable with our findings (3.10cm±0.334 cm and 3.42±0.478 respectively). The mean aortic knob diameter among females was 2.77±0.37. This value was smaller in comparison to the value obtained in the Indian ( 20 ) study of 3.076cm±0.39 cm and the south Korean( 11 ) study of 3.00±0.498 (Table 4 ). Table 4 Comparison of aortic knob diameters in different populations Authors Country Mean AKD/cm Ray et al, 2014 India Overall- 3.04cm±0.41 Male - 3.10cm±0.334 Female - 3.076±0.39cm Felson, 1973 United states of America 3.0cm Lee et al, 2018 South Korea Mean overall -3.30±0.334 Males- 3.42±0.478cm Females -3.00±0.498cm Rayner et al, 2004 United states of America Normotensives -3.28cm Hypertensives -3.69cm Magera et al, 2020 Uganda Overall- 3.03±0.39cm Male- 3.14±0.34cm Female- 2.77±0.37cm. The mean aortic knob and arch diameters were higher in males than females which is consistent with the findings of Ikeme and colleagues ( 24 ) and Ray and colleagues ( 20 ). On the contrary, a study done in Jamaica reported a higher aortic arch size in females than males ( 25 ). These findings were attributed to the higher blood pressures in females than males ( 25 ). Kim and Choi observed that an aortic knob diameter (AKD) width of more than 4 cm occurred more frequently in patients with thoracic aortic disorder as compared to normal subjects ( 26 ). In this study, there was no female with an AKD > 4cm but there were 2 males whose AKD was slightly above 4cm measured on the digital screen. These were healthy males with no cardiovascular disease and normal blood pressure for age. The AAD is another measurement for evaluation of the size of the aorta on chest radiograph ( 27 ). In this study the mean of the AAD was 5.6 ±0.64cm. This value is comparable to other values in different studies by Yousef and colleagues in Sudan ( 28 ) 5.3±0.6, and 5.3 by Umerah in Zambia ( 22 ). Anyanwu and Agwuna measured the width of the aortic shadow as the sum of the maximum extension of the aortic shadow to the right and left of the midline and found the mean of AAD varied between 4.7±0.5 cm in the Nigerian population ( 29 ). The mean THD and mean TTD were 12.9±12.6 cm and 29.07±2.78cm respectively. This was comparable to 11.9 ± 9 cm of mean THD and 27.8± 7cm of mean TTD in the Sudanese population ( 28 ). This means, our study population had higher mean of transverse heart and thoracic diameters. Aortic knob diameter correlated positively with chest and heart diameters in the Sudanese and Nigerian studies ( 21 , 28 ). In this study, we found that there was slightly higher mean AKD, when measurements done on a digital screen than on the x-ray films and the difference were statistically significant. This can be explained by the fact that digital measurements on screens are correct to the nearest millimeter, which may be difficult to achieve on the plain films due to approximation. Hence, measurements should be done on a digital screen than x-ray films in practice. This study also demonstrated that weight and height did not significantly affect the size of the aortic knob. Strengths of our study include, being a prospective study with relatively large sample size and its multi-centric nature. The limitation of the study was that it was a hospital-based study which could introduce selection bias. Moreover, the number of female participants was much smaller than the male counterparts. Conclusions And Recommendations The aortic knob diameter was higher in males and there was a positive correlation with age, aortic arch diameter, transverse heart diameter and transverse thoracic diameter. We recommend aortic knob diameter measurements should be done on digital screen than printed x ray films and sex-specific aortic knob diameters should be utilized in clinical practice. Abbreviations AAD: Aortic arch diameter AKD: Aortic knob diameter THD: Transverse heart diameter PA: Postero-anterior TTD: Transverse thoracic diameter Declarations Ethics approval and consent to participate Written informed consent was obtained from all participants to participate in the study. Ethical approval was obtained from Makerere University School of Medicine Research and Ethics committee (#REC REF 2019-107) and administrative clearance was sought from St Francis hospital, Case Hospital and Kirrudu Hospital. All procedures of the study also followed the recommendation of the Declaration of Helsinki Convention. Consent for publication Not applicable Availability of data and materials The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request. Competing interests The authors declare that they have no competing interests. Funding No funding Authors’ contribution All authors made significant contribution to the study by participating in its conception, study design, execution, acquisition of data, analysis and interpretation of the study results. The further all participated in the drafting, revising and critically reviewing the article; gave final approval of the version to be published; have agreed on the journal to which the article has been submitted; and agree to be accountable for all aspects of the work. Acknowledgements We would like to acknowledge all the lecturers and residents at the department of radiology and radiotherapy, College of Health Sciences, Makerere University for their valuable technical assistance. We also thank Mr. Okello Bonny for immense help in analysis. References Cardiovascular diseases (CVDs) [Internet]. [cited 2021 Sep 18]. Available from: https://www.who.int/news-room/fact-sheets/detail/cardiovascular-diseases-(cvds ) Stokes MB, Roberts-Thomson R. 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Clin Imaging. 2016;40(5):936–43. Yousef M, Gameraddin M, Ali A, Ahmed B. Aortic and Heart Dimensions of Adults in Sudanese’s Population using Chest X-Ray. Kärntner Bot. 2014 Jan 1; Anyanwu GE, Agwuna KK. Aortic arch diameter and its significance in the clinical evaluation of cardiac and aortic enlargements. Niger J Clin Pract. 2009 Dec;12(4):453–6. Additional Declarations No competing interests reported. Supplementary Files Appendix1.docx Appendix 1: Data Collection Tools Cite Share Download PDF Status: Published Journal Publication published 01 Mar, 2022 Read the published version in Reports in Medical Imaging → Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-944105","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":54871165,"identity":"19e2fe64-1c47-4342-bd17-519443aefb06","order_by":0,"name":"Steven Magera","email":"","orcid":"","institution":"Makerere University","correspondingAuthor":false,"prefix":"","firstName":"Steven","middleName":"","lastName":"Magera","suffix":""},{"id":54871166,"identity":"d2338d3c-a8d1-452f-b19b-265e58f77d40","order_by":1,"name":"Senai Goitom Sereke","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA2ElEQVRIiWNgGAWjYHACNgjF3gAkDCxI0cJzAKRFghQtEglgkrB6c/YzZg8+7qmTM5d8fnXDjwIJBv727gS8Wix7cswNZzw7bGw5O6fsZg/QYRJnzm7Aq8XgQI6ZNM+BA4kbbuek3eABajGQyCWg5fwbM+k/B+rqN9w8k3bzD1FabgBtYTjAnGBwg/3YbeJsufGsTLLnwGHDDWdy2G7LGEjwEPbL+eRtEj8O1MkbHD/+7OabPzZy/O29+LUwMHAYQBk8YAYPAeUgwP4AnTEKRsEoGAWjABUAAGb3SmTGofbOAAAAAElFTkSuQmCC","orcid":"","institution":"Makerere University","correspondingAuthor":true,"prefix":"","firstName":"Senai","middleName":"Goitom","lastName":"Sereke","suffix":""},{"id":54871167,"identity":"37496a17-3f98-4778-b2c3-c69e6e0019fc","order_by":2,"name":"Emmy Okello","email":"","orcid":"","institution":"Uganda Heart Institute","correspondingAuthor":false,"prefix":"","firstName":"Emmy","middleName":"","lastName":"Okello","suffix":""},{"id":54871168,"identity":"6f214776-a9ef-4a9b-827c-0919aa42133b","order_by":3,"name":"Faith Ameda","email":"","orcid":"","institution":"Makerere University","correspondingAuthor":false,"prefix":"","firstName":"Faith","middleName":"","lastName":"Ameda","suffix":""},{"id":54871169,"identity":"c52b7f2f-519d-434e-8e6c-3955cbfee3bd","order_by":4,"name":"Geoffrey Erem","email":"","orcid":"","institution":"Makerere University","correspondingAuthor":false,"prefix":"","firstName":"Geoffrey","middleName":"","lastName":"Erem","suffix":""}],"badges":[],"createdAt":"2021-09-27 17:44:06","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-944105/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-944105/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.2147/RMI.S356443","type":"published","date":"2022-03-01T20:01:56+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":14164739,"identity":"76fe0db7-5399-4d72-8fca-0e064c57b0bf","added_by":"auto","created_at":"2021-09-30 18:18:43","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":225325,"visible":true,"origin":"","legend":"Chest x-ray measurements","description":"","filename":"fig1.png","url":"https://assets-eu.researchsquare.com/files/rs-944105/v1/e0a82fc15fb754fce9a46b25.png"},{"id":19702448,"identity":"b1c69751-aaf0-42c1-8fc1-d47d3ea78bc6","added_by":"auto","created_at":"2022-03-28 20:04:45","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":624131,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-944105/v1/176f77d9-e72a-4567-a6e9-5d559834e17a.pdf"},{"id":14164740,"identity":"4ba0ae64-798d-4bbf-a64f-539b1abcfa53","added_by":"auto","created_at":"2021-09-30 18:18:43","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":13887,"visible":true,"origin":"","legend":"Appendix 1: Data Collection Tools","description":"","filename":"Appendix1.docx","url":"https://assets-eu.researchsquare.com/files/rs-944105/v1/097f54c6a385325a4198c20c.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eAortic knob diameter in chest radiographs of healthy adults in Uganda.\u003c/p\u003e","fulltext":[{"header":"Background","content":"\u003cp\u003eCardiovascular disease accounts for three quarters of all global estimated deaths in the low- and middle-income countries (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e). Chest radiograph remains an important tool for investigation of cardiovascular conditions despite the advent of newer and more sophisticated imaging modalities such as echocardiography, computerized tomography (CT) and magnetic resonance imaging (MRI) in the world (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e). This is mainly due to more readily available and comparatively cheaper costs of performing chest radiograph and still provides valuable clues to diagnosis of cardiovascular pathology (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe aorta is a major vascular supply of the human body and also plays an important role in the control of systemic vascular resistance and heart rate. This control is done via pressure-responsive receptors located in the ascending aorta and aortic arch (\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e). An increase and decrease in aortic pressure results in a decrease of heart rate and systemic vascular resistance, and an increase of heart rate and systemic vascular resistance respectively (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe Aortic knob is an important structure that refers to the hump-shaped contour of the aorta seen in a frontal chest radiograph on the left mediastinal silhouette (\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e). Abnormal aortic knuckle shape, enlargement and aortic nipple, may give the first clue of cardiovascular disease (\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e). The aortic knob can be enlarged due to increased pressure flow in aorta, increased volume or changes in the elasticity of its wall. In adults, aortic knob enlargement can be seen in systemic hypertension, valvular insufficiency, aortic dissection, traumatic aortic injury, thoracic aortic aneurysm, and atherosclerosis (\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eAortic knob diameter (AKD) has been shown to be a good predictor of target organ damage with a sensitivity ranging between 70\u0026ndash;90% for different cardiovascular conditions, even in early disease (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e). These include hypertensive heart disease, sub clinical atherosclerosis, aneurysms and aortic dissection (\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e). Moreover, aortic knob width is positively correlated with both systolic and diastolic blood pressures (\u003cspan additionalcitationids=\"CR11\" citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eUganda is a low income country and yet is experiencing a shift in major causes of death with coronary artery disease and other forms of heart failure on the rise (\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e). And the normal AKD in the literature were taken from studies done among Caucasians, Americans, South Koreans, Indians and West Africans. These studies showed that variations exist amongst different populations, age groups and between sexes (\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e). In this study therefore, we sought to determine the normal AKD amongst healthy adults in Ugandan.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy design and setting\u003c/h2\u003e \u003cp\u003eThis was a descriptive cross-sectional study conducted in three selected tertiary hospitals \u0026ndash; CASE hospital, St Francis Hospital and Kiruddu Hospital \u0026ndash; Kampala, Uganda from January 2020 to June 2020. St. Francis Hospital is located on Nsambya hill in Makindye Division, one of the five administrative divisions of the city. It lies approximately 5 kilometers southeast of the central business district of Kampala. It is a tertiary referral hospital with a capacity of 361 beds and approximately 450 chest radiographs are performed per month. Kiruddu General Hospital, is in the neighborhood of Kiruddu, on Buziga Hill, in Makindye Division, one of the five administrative units of the Kampala capital city authority. It is approximately 13 kilometers, by road, south-east of the Mulago national referral hospital. Chest radiographs are performed as part of ongoing recruitment in government agencies like police, army and local governments. Case hospital is an urban, private, tertiary hospital in Kampala, Uganda. It is located at 67 - 71 Buganda Road, on Nakasero hill. Around 100 chest radiographs are performed per a month.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eStudy population\u003c/h2\u003e \u003cp\u003eStudy participants included asymptomatic participants referred for chest radiograph examination for the purpose of pre-employment and pre-travel medical check-ups and were recruited in this study. Participants with normal chest radiograph (Posterior anterior view, erect), and age between 18-90 years, with no thoracic skeletal deformity, no known cardio-vascular disease, and normal blood pressure for age (blood pressure chart) were included in the study. Participants whose chest radiographs had significant rotation (\u0026gt;0.5cm) or artifacts were excluded from the study.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eSample size\u003c/h2\u003e \u003cp\u003eA sample size of 294 participants was used using the formula proposed by Rosner B. 2015 as summarized below.\u003c/p\u003e \u003cp\u003eN = (Z\u003csub\u003eα/2\u003c/sub\u003e+Z\u003csub\u003eβ\u003c/sub\u003e)\u003csup\u003e2\u003c/sup\u003e *2*σ\u003csup\u003e2\u003c/sup\u003e / d\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eWhere N = sample size required. Z\u003csub\u003eα/2\u003c/sub\u003e =is the critical value of the Normal distribution at α/2 (e.g. for a confidence level of 95%, α is 0.05 and the critical value is 1.96), Z\u003csub\u003eβ\u003c/sub\u003e =is the critical value of the Normal distribution at β (e.g. for a power of 80%, β is 0.2 and the critical value is 0.84), σ\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;is the population variance, d = desired level of precision/marginal error (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eN = (1.96+0.84)\u003csup\u003e2\u003c/sup\u003e *2*(4.1)\u003csup\u003e2\u003c/sup\u003e / (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e)\u003csup\u003e2\u003c/sup\u003e. N=264. Non-response of 10% was 30. Hence the sample size was 294.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eStudy Procedure\u003c/h2\u003e \u003cp\u003e Study participants who gave their consent were physically examined and enrolled into the study. A total of 294 participants\u0026rsquo; postero-anterior (PA) chest radiographs were obtained. The PA chest radiograph of all the candidates were taken in the erect position with a film focus distance of 1.8m. The exposures were made at normal arrested inspiration. Participant\u0026rsquo;s name, sex, age, height and medical history were recorded. Normal chest radiograph was confirmed by two independent radiologists. Parameters such as AKD, transverse thoracic diameter (TTD) and transverse heart diameter (THD) were evaluated for each patient (figure \u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The aortic knob diameter was measured as the maximum transverse diameter from the lateral border of the air in the trachea to the lateral border of the aortic knob (\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e). The Aortic arch diameter (AAD) was measured as the most lateral extension to the right and left of the midline at the level of the aortic knob. TTD was measured as the maximum horizontal distance between the internal margins of the chest wall at the level of the right hemi diaphragm (\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e). THD was measured as the sum of the maximum projection to the right and left heart borders from midline (\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003eData analysis\u003c/h2\u003e \u003cp\u003eA structured data collection tool was used to collect bio-demographics and relevant history (Appendix 1). Data was analyzed using STATA version 16. Descriptive statistics for continuous variables were presented as mean and standard deviation. Spear man rank correlation was used to test for the correlation between the aortic diameter measurements with continuous independent variables. In addition, Student t test was performed to test for the mean difference of AKD between groups. A p \u0026lt; 0.05 was considered statistically significant.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eA total of 294 participants, of whom 204(69.4%) were male and the age range between 18-89 years were recruited in the study. Overall, 196 (66.7%) participants were attending the hospital for pre-employment medical exam, 92 (31.3%) came for annual medical checkup exams, and 6 (2%) pre travel exams. The mean age of the participants was 35.3\u0026plusmn;10.5. (Table \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\u0026nbsp;\u003ctable border=\"1\" id=\"Tab1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eAge distribution of the participants\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eAge category\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eFemale (f, %)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eMale (f, %)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eTotal (f, %)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e18-29years\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e40(39.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e61(60.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e101(34.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e30-39years\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e27(29.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e65(70.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e92(31.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e40-49years\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e15(20.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e58(79.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e73(24.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e50-59years\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e7(28.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e18(72.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e25(8.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026ge;60 years\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1(33.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2(66.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3(1.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eTotal\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e90(30.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e204(69.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e294(100)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003cp\u003eMale participants had significantly higher mean AKD compared to their female counterparts (3.14\u0026plusmn;0.34cm versus 2.77\u0026plusmn;0.37cm, p - 0.000). Those in the age group of 50-59years had significantly higher means than younger people in the age group of 18-29 years (Table \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e and Table \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\u0026nbsp;\u003ctable border=\"1\" id=\"Tab2\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eThe mean aortic knob diameter of 294 participants.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eVariables\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eFrequency n=294\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eMean \u0026plusmn; SD /cm\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eP-value\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eGender\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e204\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.14\u0026plusmn;0.34\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" rowspan=\"2\"\u003e\n \u003cp\u003e0.000\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFemale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e90\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.77\u0026plusmn;0.37\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eAge category\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e18-29years\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e101\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.76\u0026plusmn;0.34\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" rowspan=\"5\"\u003e\n \u003cp\u003e0.000\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e30-39years\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e92\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.01\u0026plusmn;0.30\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e40-49years\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e73\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.26\u0026plusmn;0.33\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e50-59years\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.43\u0026plusmn;0.30\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026ge;60 years\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.34\u0026plusmn;0.56\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cdiv class=\"gridtable\"\u003e\u0026nbsp;\u003ctable border=\"1\" id=\"Tab3\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eComparison of aortic knob diameter in males and females by age.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eMales\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eFemales\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eAge/yrs.\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eMean/cm\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eSD\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eP- value\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eAge/yrs.\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eMean/cm\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eSD\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eP-value\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e18-29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.93\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.28\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.0000\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e18-29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.0000\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e30-39\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.07\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e30-39\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.86\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e40-49\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e40-49\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.05\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e50-59\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.46\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.27\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e50-59\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.34\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026ge;60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.69\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026ge;60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.02\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003ctfoot\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"8\"\u003eMen have higher mean aortic knob diameters among all age groups compared to the females.\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tfoot\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003cp\u003eThe mean AKD was higher when measurement was done on a digital screen than on the chest radiograph film (3.03\u0026plusmn;0.393cm versus 2.96\u0026plusmn;0.392cm, p - 0.000). However, the males still had significantly higher AKD compared to female and unit increase in age would also increase the AKD (Table \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003e).\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\u0026nbsp;\u003ctable border=\"1\" id=\"Tab4\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eThe aortic knob diameter measurement on digital screen and x-ray by gender and age groups of 294 participants.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eVariables\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003en=294\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eaortic knob diameter digital screen\u003c/p\u003e\n \u003cp\u003eMean \u0026plusmn; SD /mm\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eP-value\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eaortic knob diameter\u003c/p\u003e\n \u003cp\u003ex ray film\u003c/p\u003e\n \u003cp\u003eMean \u0026plusmn; SD /mm\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eP value\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eAortic knob diameter\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e294\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.03\u0026plusmn;0.393\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.96\u0026plusmn;0.392\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.000\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eGender\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e204\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.14\u0026plusmn;0.34\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" rowspan=\"2\"\u003e\n \u003cp\u003e0.000\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.08\u0026plusmn;0.37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" rowspan=\"2\"\u003e\n \u003cp\u003e0.000\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFemale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e90\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.77\u0026plusmn;0.37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.70\u0026plusmn;0.37\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eAge category\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e18-29years\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e101\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.76\u0026plusmn;0.34\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" rowspan=\"5\"\u003e\n \u003cp\u003e0.000\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.71\u0026plusmn;0.24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" rowspan=\"5\"\u003e\n \u003cp\u003e0.000\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e30-39years\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e92\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.01\u0026plusmn;0.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.92\u0026plusmn;0.27\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e40-49years\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e73\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.26\u0026plusmn;0.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.20\u0026plusmn;0.37\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e50-59years\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.43\u0026plusmn;0.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.39\u0026plusmn;0.47\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026ge;60 years\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.34\u0026plusmn;0.56\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.67\u0026plusmn;0.58\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003cp\u003eThe average AKD of the sample population was 3.03\u0026plusmn;0.39cm, the smallest was 2.2cm and the largest was 4.1 cm. The mean AAD of the study population was 5.63\u0026plusmn;0.64cm and average cardiothoracic ratio is 0.446\u0026plusmn;0.037 with highest being 0.522cm and lowest 0.366cm (Table \u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003e).\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\u0026nbsp;\u003ctable border=\"1\" id=\"Tab5\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 6\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eOther cardiovascular parameters on chest x-ray for 294 participants\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eVariables (unit measures)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eN\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eMean \u0026plusmn; SD\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eMinimum\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eMaximum\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAortic knob diameter (cm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e294\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.03\u0026plusmn;0.39\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4.1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAortic arch diameter (cm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e294\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e5.63\u0026plusmn;0.64\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4.11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e7.63\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eTransvers heart diameter (cm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e294\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e12.97\u0026plusmn;1.26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10.03\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e16.43\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eTransverse thoracic diameter (cm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e294\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e29.07\u0026plusmn;2.78\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e27.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e36.89\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCardiothoracic ratio\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e294\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.446\u0026plusmn;0.037\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.366\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.522\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003cp\u003eAKD was strongly and more positively correlated with age among the females than in males, the coefficient was higher among the females and the relationship was statistically significant at 95% confidence level r=0.7411 p-value 0.000 for females vs. r=0.5191 p-value 0.000 for males. Strong positive correlation was also observed between the AKD and AAD for both male and female. However, AKD was weakly correlated with THD, TTD and cardiothoracic ratio respectively (Table \u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003e).\u003c/p\u003e\n\u003cp\u003eTable 7: Correlation of the aortic knob diameter with Aortic arch diameter, transverse diameter of the chest and heart diameter for male and female population. (Spearman correlation) \u003c/p\u003e\n\u003ctable border=\"1\" cellpadding=\"0\" cellspacing=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"38.14756671899529%\"\u003e\n \u003cp\u003e\u003cstrong\u003eVariables\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.739403453689167%\"\u003e\n \u003cp\u003eCorrelation coefficient ( r ) for male\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"10.361067503924646%\"\u003e\n \u003cp\u003eP-value\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"20.722135007849293%\"\u003e\n \u003cp\u003eCorrelation coefficient ( r ) for female\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"13.029827315541601%\"\u003e\n \u003cp\u003eP-value\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"38.14756671899529%\"\u003e\n \u003cp\u003e\u003cstrong\u003eAge\u003c/strong\u003e(years)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.739403453689167%\"\u003e\n \u003cp\u003e0.5191\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"10.361067503924646%\"\u003e\n \u003cp\u003e0.05\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"20.722135007849293%\"\u003e\n \u003cp\u003e0.7411\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"13.029827315541601%\"\u003e\n \u003cp\u003e0.05\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"38.14756671899529%\"\u003e\n \u003cp\u003e\u003cstrong\u003eAortic arch diameter\u003c/strong\u003e/cm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.739403453689167%\"\u003e\n \u003cp\u003e0.6136\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"10.361067503924646%\"\u003e\n \u003cp\u003e0.05\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"20.722135007849293%\"\u003e\n \u003cp\u003e0.6518\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"13.029827315541601%\"\u003e\n \u003cp\u003e0.05\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"38.14756671899529%\"\u003e\n \u003cp\u003e\u003cstrong\u003eTransverse Heart diameter\u003c/strong\u003e/cm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.739403453689167%\"\u003e\n \u003cp\u003e0.4879\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"10.361067503924646%\"\u003e\n \u003cp\u003e0.05\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"20.722135007849293%\"\u003e\n \u003cp\u003e0.4869\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"13.029827315541601%\"\u003e\n \u003cp\u003e0.05\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"38.14756671899529%\"\u003e\n \u003cp\u003e\u003cstrong\u003eTransverse thoracic diameter\u003c/strong\u003e/cm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.739403453689167%\"\u003e\n \u003cp\u003e0.2007\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"10.361067503924646%\"\u003e\n \u003cp\u003e0.05\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"20.722135007849293%\"\u003e\n \u003cp\u003e0.4555\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"13.029827315541601%\"\u003e\n \u003cp\u003e0.05\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"38.14756671899529%\"\u003e\n \u003cp\u003e\u003cstrong\u003eCardiothoracic ratio\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.739403453689167%\"\u003e\n \u003cp\u003e0.3433\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"10.361067503924646%\"\u003e\n \u003cp\u003e0.05\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"20.722135007849293%\"\u003e\n \u003cp\u003e0.1914\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"13.029827315541601%\"\u003e\n \u003cp\u003e0.05\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eWeight and height were weakly correlated though positively associated with the aortic knob diameter across both genders. However, it was all higher among the female counterpart and the relationships were not statistically significant at 95% confidence level.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis study sought to determine the aortic knob diameter in chest radiographs of healthy adults in Uganda. The results of our study showed that AKD increases with age in both sexes. This can be explained by geometric and functional alterations seen with aging (\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e). Studies in India, Nigeria, Zambia, United States and South Korea also showed similar results (\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan additionalcitationids=\"CR21\" citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eAKD was higher in males than in females. Among males, the mean average diameter of aortic knob was 3.14\u0026plusmn;0.34cm. Population based large cohort study in Netherlands showed that men had higher mean thoracic aorta diameter than women but provided no explanation as to why (\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e). Mean AKD findings in Indian population (\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e) and South Korean population (\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e) were comparable with our findings (3.10cm\u0026plusmn;0.334 cm and 3.42\u0026plusmn;0.478 respectively). The mean aortic knob diameter among females was 2.77\u0026plusmn;0.37. This value was smaller in comparison to the value obtained in the Indian (\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e) study of 3.076cm\u0026plusmn;0.39 cm and the south Korean(\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e) study of 3.00\u0026plusmn;0.498 (Table \u003cspan refid=\"Tab7\" class=\"InternalRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab7\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison of aortic knob diameters in different populations\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAuthors\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCountry\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMean AKD/cm\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eRay et al, 2014\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eIndia\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eOverall- 3.04cm\u0026plusmn;0.41\u003c/p\u003e \u003cp\u003eMale - 3.10cm\u0026plusmn;0.334\u003c/p\u003e \u003cp\u003eFemale - 3.076\u0026plusmn;0.39cm\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eFelson, 1973\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eUnited states of America\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.0cm\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eLee et al, 2018\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eSouth Korea\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMean overall -3.30\u0026plusmn;0.334\u003c/p\u003e \u003cp\u003eMales- 3.42\u0026plusmn;0.478cm\u003c/p\u003e \u003cp\u003eFemales -3.00\u0026plusmn;0.498cm\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eRayner et al, 2004\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eUnited states of America\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eNormotensives -3.28cm\u003c/p\u003e \u003cp\u003eHypertensives -3.69cm\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMagera et al, 2020\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eUganda\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eOverall- 3.03\u0026plusmn;0.39cm\u003c/p\u003e \u003cp\u003eMale- 3.14\u0026plusmn;0.34cm\u003c/p\u003e \u003cp\u003eFemale- 2.77\u0026plusmn;0.37cm.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThe mean aortic knob and arch diameters were higher in males than females which is consistent with the findings of Ikeme and colleagues (\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e) and Ray and colleagues (\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e). On the contrary, a study done in Jamaica reported a higher aortic arch size in females than males (\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e). These findings were attributed to the higher blood pressures in females than males (\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eKim and Choi observed that an aortic knob diameter (AKD) width of more than 4 cm occurred more frequently in patients with thoracic aortic disorder as compared to normal subjects (\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e). In this study, there was no female with an AKD \u0026gt; 4cm but there were 2 males whose AKD was slightly above 4cm measured on the digital screen. These were healthy males with no cardiovascular disease and normal blood pressure for age.\u003c/p\u003e \u003cp\u003eThe AAD is another measurement for evaluation of the size of the aorta on chest radiograph (\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e). In this study the mean of the AAD was 5.6 \u0026plusmn;0.64cm. This value is comparable to other values in different studies by Yousef and colleagues in Sudan (\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e) 5.3\u0026plusmn;0.6, and 5.3 by Umerah in Zambia (\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e). Anyanwu and Agwuna measured the width of the aortic shadow as the sum of the maximum extension of the aortic shadow to the right and left of the midline and found the mean of AAD varied between 4.7\u0026plusmn;0.5 cm in the Nigerian population (\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe mean THD and mean TTD were 12.9\u0026plusmn;12.6 cm and 29.07\u0026plusmn;2.78cm respectively. This was comparable to 11.9 \u0026plusmn; 9 cm of mean THD and 27.8\u0026plusmn; 7cm of mean TTD in the Sudanese population (\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e). This means, our study population had higher mean of transverse heart and thoracic diameters. Aortic knob diameter correlated positively with chest and heart diameters in the Sudanese and Nigerian studies (\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn this study, we found that there was slightly higher mean AKD, when measurements done on a digital screen than on the x-ray films and the difference were statistically significant. This can be explained by the fact that digital measurements on screens are correct to the nearest millimeter, which may be difficult to achieve on the plain films due to approximation. Hence, measurements should be done on a digital screen than x-ray films in practice. This study also demonstrated that weight and height did not significantly affect the size of the aortic knob.\u003c/p\u003e \u003cp\u003eStrengths of our study include, being a prospective study with relatively large sample size and its multi-centric nature. The limitation of the study was that it was a hospital-based study which could introduce selection bias. Moreover, the number of female participants was much smaller than the male counterparts.\u003c/p\u003e "},{"header":"Conclusions And Recommendations","content":"\u003cp\u003eThe aortic knob diameter was higher in males and there was a positive correlation with age, aortic arch diameter, transverse heart diameter and transverse thoracic diameter. We recommend aortic knob diameter measurements should be done on digital screen than printed x ray films and sex-specific aortic knob diameters should be utilized in clinical practice.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eAAD: Aortic arch diameter\u003c/p\u003e\n\u003cp\u003eAKD: Aortic knob diameter\u003c/p\u003e\n\u003cp\u003eTHD: Transverse heart diameter\u0026nbsp;\u003c/p\u003e\n\u003cp\u003ePA: Postero-anterior\u003c/p\u003e\n\u003cp\u003eTTD: Transverse thoracic diameter\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWritten informed consent was obtained from all participants to participate in the study. Ethical approval was obtained from Makerere University School of Medicine Research and Ethics committee (#REC REF 2019-107) and administrative clearance was sought from St Francis hospital, Case Hospital and Kirrudu Hospital.\u0026nbsp;All procedures of the study also followed the recommendation of the Declaration of Helsinki Convention.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo funding\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026rsquo; contribution\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll authors made significant contribution to the study by participating in its conception, study design, execution, acquisition of data, analysis and interpretation of the study results. The further all participated in the drafting, revising and critically reviewing the article; gave final approval of the version to be published; have agreed on the journal to which the article has been submitted; and agree to be accountable for all aspects of the work.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe would like to acknowledge all the lecturers and residents at the department of radiology and radiotherapy, College of Health Sciences, Makerere University for their valuable technical assistance. We also thank Mr. Okello Bonny for immense help in analysis. \u0026nbsp;\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eCardiovascular diseases (CVDs) [Internet]. [cited 2021 Sep 18]. Available from: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.who.int/news-room/fact-sheets/detail/cardiovascular-diseases-(cvds\u003c/span\u003e\u003c/span\u003e)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eStokes MB, Roberts-Thomson R. The role of cardiac imaging in clinical practice. Aust Prescr. 2017 Aug;40(4):151\u0026ndash;5.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePuddy E, Hill C. Interpretation of the chest radiograph. Contin Educ Anaesth Crit Care Pain. 2007 Jun;7(3):71\u0026ndash;5.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eArmstrong M, Kerndt CC, Moore RA. Physiology, Baroreceptors. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 [cited 2021 Sep 18]. Available from: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttp://www.ncbi.nlm.nih.gov/books/NBK538172/\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMayet J, Hughes A. Cardiac and vascular pathophysiology in hypertension. Heart. 2003 Sep;89(9):1104\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eXue Z, Long R, Jaeger S, Folio L, George Thoma R, Antani and S. Extraction of Aortic Knuckle Contour in Chest Radiographs Using Deep Learning. In: 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) [Internet]. Honolulu, HI: IEEE; 2018 [cited 2021 Sep 18]. p.\u0026nbsp;5890\u0026ndash;3. Available from: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://ieeexplore.ieee.org/document/8513560/\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJain D, Dietz HC, Oswald GL, Maleszewski JJ, Halushka MK. Causes and histopathology of ascending aortic disease in children and young adults. Cardiovasc Pathol Off J Soc Cardiovasc Pathol. 2011;20(1):15\u0026ndash;25.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGoldstein SA, Evangelista A, Abbara S, Arai A, Asch FM, Badano LP, et al. Multimodality Imaging of Diseases of the Thoracic Aorta in Adults: From the American Society of Echocardiography and the European Association of Cardiovascular Imaging: Endorsed by the Society of Cardiovascular Computed Tomography and Society for Cardiovascular Magnetic Resonance. J Am Soc Echocardiogr. 2015 Feb 1;28(2):119\u0026ndash;82.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHalilu SD, Aiyekomogbon JO. The usefulness of aortic arch width measurements on chest radiographs of adult patients with systemic hypertension and hypertensive heart disease. New Niger J Clin Res. 2018 Feb 1;7(12):51.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRayner BL, Goodman H, Opie LH. The chest radiograph. A useful investigation in the evaluation of hypertensive patients. Am J Hypertens. 2004 Jun;17(6):507\u0026ndash;10.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLee E-J, Han J-H, Kwon K-Y, Kim J-H, Han K-H, Sung S-Y, et al. The Relationship between Aortic Knob Width and Metabolic Syndrome. Korean J Fam Med. 2018 Jul;39(4):253\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eErkan H, Korkmaz L, Ağa\u0026ccedil; MT, Acar Z, Kiriş A, Erkan M, et al. Relation between carotid intima-media thickness and aortic knob width in patients with essential hypertension. Blood Press Monit. 2011 Dec;16(6):282\u0026ndash;4.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMusinguzi G, Wanyenze RK, Ndejjo R, Ssinabulya I, van Marwijk H, Ddumba I, et al. An implementation science study to enhance cardiovascular disease prevention in Mukono and Buikwe districts in Uganda: a stepped-wedge design. BMC Health Serv Res. 2019 Apr 25;19(1):253.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAfsar B, Saglam M, Yuceturk C, Agca E. The relationship between aortic knob width and various demographic, clinical, and laboratory parameters in stable hemodialysis patients. Saudi J Kidney Dis Transplant Off Publ Saudi Cent Organ Transplant Saudi Arab. 2014 Nov;25(6):1178\u0026ndash;85.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFelson B. A review of over 30,000 normal chest roentgenograms. Chest Roentgenol. 1973;494\u0026ndash;5.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKabala JE, Wilde P. The measurement of heart size in the antero-posterior chest radiograph. Br J Radiol. 1987 Oct;60(718):981\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eUngerleider HE, Gubner R. Evaluation of heart size measurements. Am Heart J. 1942;24(4):494\u0026ndash;510.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMitchell JRA, Schwartz CJ. Arterial disease. Blackwell Scientific Publications; 1965.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eREDHEUIL A, YU W-C, MOUSSEAUX E, HAROUNI AA, KACHENOURA N, Wu CO, et al. Age-Related Changes in Aortic Arch Geometry: Relationship with Proximal Aortic Function and Left Ventricular Mass and Remodeling. J Am Coll Cardiol. 2011 Sep 13;58(12):1262\u0026ndash;70.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRay A, Mandal D, Kundu P, Manna S, Mandal S. Aortic knob diameter in chest X-ray and its relation with age, heart diameter and transverse diameter of thorax in a population of Bankura district of West Bengal, India: a cross sectional study. J Evol Med Dent Sci. 2014 Jul 31;3(31):8595+.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eObikili EN, Okoye IJ. Aortic arch diameter in frontal chest radiographs of a normal Nigerian population. Niger J Med J Natl Assoc Resid Dr Niger. 2004 Jun;13(2):171\u0026ndash;4.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eUmerah BC. Unfolding of the aorta (aortitis) associated with pulmonary tuberculosis. Br J Radiol. 1982 Mar;55(651):201\u0026ndash;3.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBons LR, Rueda-Ochoa OL, Ghoul KE, Rohde S, Budde RP, Leening MJ, et al. Sex-specific distributions and determinants of thoracic aortic diameters in the elderly. Heart. 2020 Jan 1;106(2):133\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eIkeme AC, Ogakwu MA, Nwakonobi FA. The significance of the enlargement of the aortic shadow in adult Nigerians. Afr J Med Med Sci. 1976 Sep;5(3):195\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eStuart KL, Miall WE, Tulloch JA, Christian DE. DILATATION AND UNFOLDING OF THE AORTA IN A JAMAICAN POPULATION. Br Heart J. 1962 Jul;24(4):455\u0026ndash;63.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKim KT, Choi YH. Nontraumatic Disorders in Mediastinum and Thoracic Aorta: Chest RadiographicFindings. J Korean Soc Emerg Med. 2016 Jun 10;11(1):72\u0026ndash;82.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMcComb BL, Munden RF, Duan F, Jain AA, Tuite C, Chiles C. Normative reference values of thoracic aortic diameter in American College of Radiology Imaging Network (ACRIN 6654) arm of the National Lung Screening Trial. Clin Imaging. 2016;40(5):936\u0026ndash;43.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYousef M, Gameraddin M, Ali A, Ahmed B. Aortic and Heart Dimensions of Adults in Sudanese\u0026rsquo;s Population using Chest X-Ray. K\u0026auml;rntner Bot. 2014 Jan 1;\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAnyanwu GE, Agwuna KK. Aortic arch diameter and its significance in the clinical evaluation of cardiac and aortic enlargements. Niger J Clin Pract. 2009 Dec;12(4):453\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Aortic knob, diameter, chest radiograph, cardiovascular, Uganda","lastPublishedDoi":"10.21203/rs.3.rs-944105/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-944105/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eThe burden of cardiovascular diseases, such as aortic and degenerative diseases grows in the aging population. Chest radiograph still plays an important role in the diagnosis of cardiovascular diseases. Aortic knob diameter in chest radiographs can be used to evaluate early changes of the aortic structure and together with clinical and laboratory findings. This study was aimed at determining the mean values of aortic knob diameter among healthy adults in Uganda.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eWe conducted a descriptive cross-sectional study in three selected hospitals in Kampala Uganda. All participants had normal chest radiographs without radiological evidence of cardiovascular disease. Chest radiograph findings extracted included aortic knob diameter, aortic arch diameter, transverse heart diameter and transverse thoracic diameter. All films were independently examined by two experienced radiologists.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eWe analyzed chest radiograph findings of 294 participants, of which 204 (69.4%) were male. Aortic knob diameter increased with age (p \u0026ndash; 0.000). The mean aortic knob diameter of males was higher than for females (3.14\u0026plusmn;0.34cm versus 2.77\u0026plusmn;0.37cm, p \u0026ndash; 0.000). The mean aortic knob diameter on the digital screen were higher than plain films (3.03\u0026plusmn;0.393cm versus 2.96\u0026plusmn;0.392cm, p \u0026ndash; 0.000). Aortic knob diameter positively correlated with age (p \u0026ndash; 0.000) and aortic arch diameter (p \u0026ndash; 0.000). Aortic knob diameter also correlated positively with transverse thoracic diameter (p \u0026ndash; 0.05), transverse heart diameter (p \u0026ndash; 0.05) and cardiothoracic ratios (p \u0026ndash; 0.05).\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eThe aortic knob diameter was higher in males and there was a positive correlation with age, aortic arch diameter, transverse heart diameter and transverse thoracic diameter. Aortic knob diameter measurements should be done on digital screen than printed x ray films.\u003c/p\u003e","manuscriptTitle":"Aortic knob diameter in chest radiographs of healthy adults in Uganda.","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2021-09-30 18:18:41","doi":"10.21203/rs.3.rs-944105/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"010e322c-9de9-4814-ab37-593316544032","owner":[],"postedDate":"September 30th, 2021","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[{"id":7562706,"name":"Nuclear Medicine \u0026 Medical Imaging"}],"tags":[],"updatedAt":"2022-03-28T20:01:56+00:00","versionOfRecord":{"articleIdentity":"rs-944105","link":"https://doi.org/10.2147/RMI.S356443","journal":{"identity":"reports-in-medical-imaging","isVorOnly":true,"title":"Reports in Medical Imaging"},"publishedOn":"2022-03-01 20:01:56","publishedOnDateReadable":"March 1st, 2022"},"versionCreatedAt":"2021-09-30 18:18:41","video":"","vorDoi":"10.2147/RMI.S356443","vorDoiUrl":"https://doi.org/10.2147/RMI.S356443","workflowStages":[]},"version":"v1","identity":"rs-944105","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-944105","identity":"rs-944105","version":["v1"]},"buildId":"_2-kVJe1T_tPrBINL-cwx","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}