{"paper_id":"7c78ed0e-6c0b-488f-8b05-be5eca800a5f","body_text":"Incidental thyroid nodules on Covid 19-related thoracic tomography scans: A giant cohort | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Incidental thyroid nodules on Covid 19-related thoracic tomography scans: A giant cohort Burcak Cavnar Helvacı, Didem Ozdemir, Kubra Turan, Caglar Keskin, and 5 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-2876461/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 16 Dec, 2023 Read the published version in Hormones → Version 1 posted 6 You are reading this latest preprint version Abstract Introduction: Computerized thoracic tomography (CT) imaging was extensively employed, especially in the early era of the Coronavirus pandemic. An incidental thyroid nodule (ITN) is defined as a nodule not previously detected or suspected clinically but identified by an imaging study. This study aimed to determine the incidence of thyroid nodules incidentally detected in thoracic CTs for the suspicion of Covid-19 pneumonia. Materials and methods Adult patients who underwent thoracic CT in our hospital for Covid-19 management between March 2020 and September 2020 were retrospectively identified. Medical information registered in the hospital and national health system were reviewed. The prevalence of incidental thyroid nodules at CT, thyroid function test results of patients with incidental lesions, correlation of CT findings with ultrasonography (US) findings, and fine-needle aspiration biopsy (FNAB) results were evaluated. Results We determined 36.939 adult patients that had a CT scan. Among these, 624 had a previous history of thyroid operation, and 1201 had already been diagnosed with a thyroid pathology. The final analysis included 35.113 patients. There was information about the thyroid gland in CT reports of 3049 patients. The prevalence of ITN was 3.82% (1343/35113 patients), and thyroid heterogeneity was 1.11% (388/35113 patients). While it was explicitly stated that no pathology was found in the thyroid gland in 3.75% (1318/35113) of the patients, no information was given about the thyroid gland in 91.32% (32064/35113) of the patient. Thus, the number of patients informed about the thyroid was 3049 (8.68%), and the number of patients with thyroid pathology was 1731 (4.93%). It was observed that 308 of 1731 (17.80%) patients had follow-up thyroid US. An FNAB was indicated in 238 (87.50%) patients. Of the 238 patients with biopsy indication, only 115 (48.31%) underwent a thyroid FNAB. The cytological diagnosis was benign in 59 (51.30%), non-diagnostic in 30 (26.08%), atypia of uncertain significance in 22 (19.13%), suspected follicular neoplasia/follicular neoplasia in 4 (3.46%) patients. Thyroidectomy was performed in six more patients due to giant nodules, and the final diagnosis was benign in 2 and papillary thyroid cancer in 3 patients. Conclusion In conclusion, increased use of thoracic CT during Covid 19 pandemic probably caused increased detection of ITNs. In this large-scale study, the prevalence of thyroid nodules reported in thoracic CT was 3.82%, and thyroid cancer was detected in 1.30% of patients evaluated in the US. Therefore, Thoracic CT scans taken for different reasons might provide the opportunity for early diagnosis and treatment of thyroid cancers. incidental thyroid nodules pandemic covid-19 Figures Figure 1 INTRODUCTION Coronavirus disease ( COVID - 19 ) is an infectious disease caused by the SARS-CoV-2 virus. COVID-19 has spread rapidly since Dec 31, 2019, the first official case date in the world. During the SARS-CoV-2 pandemic, many multifaceted health problems, such as deaths from the disease, prolonged stay in hospital and/or intensive care, and long-term covid-related and psychological issues associated with quarantines and isolation, were experienced. In addition, forced negligence of non-covid-related disorders, such as postponing elective surgeries, delays in screening programs, and routine follow-up visits, also caused significant morbidity, defined as \"collateral damage.\" Last but not least, computerized thoracic tomography (CT) imaging was extensively employed, especially in the early era of the pandemic. While this increase in imaging studies is associated with radiation exposure, some epiphanies, such as the early detection of small lung cancers, have also been encountered ( 1 ). An incidental thyroid nodule (ITN) is defined as a nodule not previously detected or suspected clinically but identified by an imaging study. The prevalence of ITN on thoracic CT in the adult population is 16–25% ( 1 , 2 ). Most ITNs are benign and small. Additionally, it is usually slow-growing even if an incidental thyroid malignancy is detected. Nevertheless, it should not be ignored that some types can show an aggressive course. On the other hand, current practice for reporting thyroid nodules on CT and magnetic resonance imaging (MRI) by radiologists is highly variable. Some radiologists may notify all ITNs because of the possibility of malignancy. Others may not report any ITN thinking that thyroid cancers in ITNs are relatively rare and small thyroid cancers usually take an indolent course ( 3 – 6 ). Imaging films may be reported focused on answering the primary clinical question and not scrutinized for the presence of coincidental pathologies or lesions. T he necessity of being fast in diagnosis and treatment due to the nature of the pandemic has made diagnosing and treating thyroid cancer more complicated. This study aimed to determine the incidence of thyroid nodules incidentally detected in thoracic CTs for the suspicion of Covid-19 pneumonia. MATERIALS AND METHODS Adult patients who underwent thoracic CT in our hospital for Covid-19 management between March 2020 and September 2020 were retrospectively identified. Medical information registered in the hospital and national health system were reviewed. The prevalence of incidental thyroid nodules at CT, thyroid function test results of patients with incidental lesions, correlation of CT findings with ultrasonography (US) findings, and fine-needle aspiration biopsy (FNAB) results were evaluated. Patients younger than 18 years old were excluded. Those with a known thyroid disease and a history of previous thyroid operation or radiotherapy to the head and neck region were also excluded. After removing repetitions, there remained 36.939 adult patients with a CT scan. Among these, 624 had a previous history of thyroid operation, and 1201 had already been diagnosed with a thyroid pathology. The final analysis included 35.113 patients. There was information about the thyroid gland in CT reports of 3049 patients. They were classified as 1) those with ITN, 2) those with thyroid heterogeneity, and 3) those without thyroid pathology. (The flowchart of the study protocol is given in Fig. 1 .) Thoracic CT scans were evaluated and reported by different radiologists. We did a text search for \"thyroid nodule\" OR \"thyroid\" OR \"thyroid heterogeneity\" OR \"calcification\" in all CT imaging reports. The presence of thyroid nodules or thyroid heterogeneity in the CT report was accepted as thyroid pathology. Thyrotrophin (TSH), free triiodothyronine (fT3), free thyroxine (fT4), antithyroid peroxidase antibody (anti-TPO), antithyroglobulin antibody (anti-Tg), and calcitonin values of patients with thyroid pathology were scanned. Thyroid function tests were performed within three months after CT scans were evaluated. Chemiluminescence methods (Immulite 1000, Immulite 2000, Immulite 2000 XPi Siemens Healthineers Headquarters, Siemens Healthcare GmbH Henkestr. 127 91052 Erlangen, Germany) were used for measurement of serum levels of TSH, fT3, and fT4, anti-TPO, and anti-Tg. The normal ranges for TSH, fT3, fT4, anti-TPO, anti-Tg, and calcitonin were 0.4 to 4 mIU/mL, 2.3 to 4.2 pg/mL, 0.89 to 1.76 ng/dL, 0 to 60 IU/mL, 0 to 1.3 IU/mL, and 0 to 5 ng/L respectively. The thyroid antibody levels greater than the upper range were accepted as positive. An abnormally high TSH with low fT3 and fT4 levels means hypothyroidism. An unusually low TSH with high fT3 and fT4 levels means hyperthyroidism. US after CT was performed in endocrinology or radiology departments. Thyroid FNAB was evaluated according to the Bethesda classification. It defined the reporting system into six different diagnostic criteria, with each having a different risk of malignancy: (i) non-diagnostic or unsatisfactory; (ii) benign; (iii) atypia of undetermined significance (AUS) or follicular lesion of undetermined significance (FLUS); (iv) follicular neoplasm or suspicious for a follicular neoplasm; (v) suspicious for malignancy; and (vi) malignant. As determined by surgical pathology, the risk of malignancy is estimated in each category and used to guide treatment decisions with ongoing clinical observation or surgical resection. Data were entered into an Excel spreadsheet (2013; Microsoft, Redmond, Washington). Shapiro-Wilk's test and normality graphs examined the distributions of continuous variables. All continuous variables were summarized by median (range), whereas categorical variables were reported as frequency (%). In addition, Mann-Whitney U and chi-square tests were performed to compare continuous and categorical variables, respectively. All statistical analyses were performed via IBM SPSS Statistics version 21.0. (IBM Corp, IBM SPSS Statistics for Windows, Armonk, NY). A P value < .05 was considered statistically significant. The local ethical committee approved the study protocol (Aug 19, 2020 – E1-20-872). RESULTS The data of 35.113 patients were analyzed. There were 20294 male (57.70%) and 14819 (42.30%) female subjects with a mean age of 48 ± 18 (19–102). The prevalence of ITN was 3.82% (1343/35113 patients), and thyroid heterogeneity was 1.11% (388/35113 patients). While it was explicitly stated that no pathology was found in the thyroid gland in 3.75% (1318/35113) of the patients, no information was given about the thyroid gland in 91.32% (32064/35113) of the patients (Table 1 ). Thus, the number of patients informed about the thyroid was 3049 (8.68%), and the number of patients with thyroid pathology was 1731 (4.93%). Table 1 Thyroid gland findings on thoracic computed tomography Frequency Percent (%) No pathology 1318 3.75 Heterogenous thyroid 388 1.11 Thyroid nodule 1343 3.82 No information about thyroid 32064 91.32 The mean age of patients with thyroid pathology on thoracic CT was 63 ± 15, and the mean age of patients without thyroid pathology was 53 ± 15 (p < 0.001). In addition, thyroid pathology was more frequent in female subjects than male subjects (42.10% vs. 57.90% p < 0.001). 96 of 162 (59.20%) female patients and 29 of 72 (40.20%) male patients had multiple nodules (p = 0.007). However, there was no statistically significant relationship between age and having single or multiple nodules (p = 0.561), with the mean age of patients with solitary nodules being 60 ± 13 and multiple nodules being 61 ± 13. A thyroid function test was performed on 1271 (73.40%) patients with thyroid pathology on CT. Of the patients, 902 (70.96%) were evaluated as euthyroid, 49 (3.85%) as overt hypothyroidism, 5 (0.39%) as subclinical hypothyroidism, 167 (13.13%) as subclinical hyperthyroidism, 22 (1.73%) as overt hyperthyroidism and 128 (10.07%) as non-thyroidal illness syndrome. Anti-TPO was positive in 241 (61.79%) of 390 patients tested for antibodies. Anti-Tg was positive in 127 (%38.36) of 331 patients who were tested for antibodies. Calcitonin value was evaluated in 124 (9.85%) patients; only six had results above the reference range. In the outpatient clinic follow-ups, seven patients were diagnosed with Graves disease, 2 with toxic adenoma, and 3 with toxic multinodular goiter. Of 1731 patients with thyroid pathology on CT, 439 died due to Covid-19 infection. Thyroid function tests were available in 293 patients who died and 978 patients who survived. Euthyroidism was detected in 902 patients. In addition, there were 128 patients with non-thyroidal illness syndrome. Hypothyroidism and hyperthyroidism were observed in 52 and 189 patients, respectively. Mortality rates according to thyroid function status are presented in Table 2 . When euthyroid patients were compared with non-euthyroid patients, the former group had better survival (16.51% vs. 39.02%, p < 0.001). Mortality was higher in patients with non-thyroidal illness syndrome compared to euthyroid subjects (62.50% vs. 16.51%, p < 0.001). A pairwise Kruskall-Wallis analysis did not demonstrate an association between overt or subclinical hypothyroidism and hyperthyroidism with survival (p > 0.05). Table 2 Mortality according to thyroid functional status Exitus n = 293 (%) Survivor n = 978 (%) P value Non-Thyroidal Illness Syndrome 80 (18.22%) 48 (3.72%) < 0.001 Euthyroidism 149 (50.85%) 753 (76.99%) < 0.001 Hypothyroidism Subclinical Overt 2 (0.68%) 6 (2.04%) 3 (0.30%) 41 (4.19%) .367 .087 Hyperthyroidism Subclinical Overt 48 (16.38%) 8 (2.73%) 119 (12.16%) 14 (1.43%) .061 .974 Radiologists have recommended thyroid US for every patient with thyroid pathology. When medical records of the hospital and national health system were examined, it was observed that 308 of 1731 (17.80%) patients had follow-up thyroid US. It was performed in another hospital in 27 (8.77%) and our hospital in 281 (91.23%) patients. Thyroid pathology was not detected in the US in 8 (2.59%) patients on CT. Ultrasonographically, there was chronic thyroiditis without nodule in 28 (9.09%), nodular goiter in 26 (8.44%), and multinodular goiter in 246 (79.87%) patients. Because different physicians performed US, localization and features of nodules were also defined differently. An FNAB was indicated in 238 (87.50%) patients. While 109 (40.07%) patients had a single nodule with FNAB indication, 129 (59.92%) had more than one nodule that needed to be evaluated by FNAB. Of the 238 patients with biopsy indication, only 115 (48.31%) underwent a thyroid FNAB, and the mean age of these patients was 56.18 ± 13.21 [SD] years. The cytological diagnosis was benign in 59 (51.30%), non-diagnostic in 30 (26.08%), atypia of uncertain significance in 22 (19.13%), suspected follicular neoplasia/follicular neoplasia in 4 (3.46%) patients. Re-biopsy was recommended for 30 patients with non-diagnostic cytology and 22 patients with atypia of uncertain significance cytology. All patients with follicular neoplasia/suspected follicular neoplasia underwent thyroidectomy, and histopathological diagnosis was follicular adenoma in 2, benign nodular disease in 1, and well-differentiated thyroid tumor with uncertain malignant potential in 1 patient. Thyroidectomy was performed in six more patients due to giant nodules, and the final diagnosis was benign in 2 and papillary thyroid cancer in 3 patients. At the same time, we could not reach the result for one patient operated on in another clinic. Operation indications and histopathological diagnosis are summarized in Table 3 . Malignancy rates were 0.30% (4/1343) in patients with ITNs on CT, 1.30% (4/308) in patients evaluated with the US, and 3.47% (4/115) in patients who underwent a biopsy. Table 3 Thyroidectomy indications and histopathological results Indication Histopathology Patient 1 FNAB resulted in follicular neoplasia Benign Patient 2 FNAB resulted in follicular neoplasia Follicular adenoma Patient 3 FNAB resulted in follicular neoplasia Follicular adenoma Patient 4 FNAB resulted as suspicious for follicular neoplasia Well-differentiated thyroid tumor with uncertain malignant potential Patient 5 Giant nodule Benign Patient 6 Giant nodule Benign Patient 7 Giant nodule Papillary microcarcinoma Patient 8 Giant nodule Papillary microcarcinoma Patient 9 Giant nodule Papillary carcinoma Patient 10 Giant nodule Unknown result DISCUSSION CT is the most common imaging modality in which ITNs are detected ( 7 ). Mainly because of the wide availability of thoracic CT to evaluate various medical conditions, the discovery of ITNs is steadily increasing. At the same time, the Covid-19 pandemic undoubtedly further contributed to this increment. Especially in the early days of the pandemic, the use of CT had significantly increased since PCR diagnostic tests did not have sufficient sensitivity, and chest X-rays did not make an early diagnosis. Theoretically, increasing CT scans may be associated with an increased incidence of ITNs. However, in practice, due to the nature of the pandemic, thoracic CT scans are evaluated by different radiologists and reported quickly. Thus, sufficient information about the thyroid gland may not be given in the CT reports. Our study showed that the prevalence of thyroid heterogeneity was 1.10%, and ITNs were 3.80% on thoracic CT in the adult population. Our finding is much less than the prevalence of 25.10% reported in 2012 by Ahmed et al. ( 2 ), who evaluated 3077 consecutive adult patients in their recent study. They found age as the most critical determinant of the significance of ITNs on thoracic CT. While the mean age of the patients included in their study was 59.30, in our study, the mean age was 48.23. Although approximately 24000 thoracic CT scans were taken in six months in our hospital in the pre-pandemic period, this number reached about 38000 in the first six months of the pandemic period. Another reason for the lower prevalence in our study compared to previous studies might be this increased number of CT scans which needed to be reported faster due to the nature of the pandemic by the same number of radiologists. In addition, technical differences such as the image quality of the CT, using intravenous contrast, and taking thin sections of the image might also cause different prevalences in different studies. In the study by Ahmed et al., in addition to age, female gender was also associated with thyroid nodules detected in CT ( 2 ). However, in the study by Ezzat S. et al., they did not find a correlation between age and nodule frequency ( 8 ). Like the Ahmed et al. study, the female gender was associated with our study's nodules and multiple nodules. Major sets of guidelines for the follow-up and management of ITNs are established by the American Thyroid Association (ATA) and the British Thyroid Association ( 10 , 11 ). Although it is proposed that patients with ITNs larger than 1 cm undergo US for further evaluation in some guidelines ( 12 ), it was reported that utilizing a three-component grading system that stratifies nodules according to risk increases diagnostic accuracy in the study by Nguyen et al. ( 13 ). They compared the performance of 2 risk-categorization methods of selecting CT-detected ITNs for workup. Method A was based simply on nodule size. They made the 3-tiered system for ITNs malignancy risk evaluation for method B: Risk category 1 is a nodule of any size with aggressive imaging features of invasive (such as local invasion, suspicious lymphadenopathy) or metastatic disease. Risk category 2 is a nodule of any size in a patient younger than 35 years of age and not meeting the criteria for risk category 1. Risk category 3 is a nodule at or above a cutoff of 15 mm and not meeting the criteria for categories 1 and 2. The 15-mm cutoff is intended to reflect a higher size threshold for the workup of nodules that lack aggressive imaging findings or demographic risk factors. The purpose of having three risk categories is to help the radiologist communicate the risk of malignancy in a CT-detected ITN and the need for further investigation by sonography. Compared with the common practice of a 10-mm-size cutoff, the 3-tiered system reduces excess workup of benign ITNs while capturing the same proportion of thyroid malignancies and is no more likely to miss high-mortality malignancies. While it would be ideal for a categorization method not to miss all incidental thyroid malignancies, it may be more rational and cost-effective to capture all malignancies associated with poor outcomes. Although most thyroid nodules were benign by cytological and histopathological evaluations, thyroid malignancies were also detected in our study population. Despite relatively low (about 5%) cancer risk, most nodules 1 cm or greater are sampled with US-guided FNAB. This situation might cause a marked increase in papillary microcarcinomas ( 13 ). A previous study of adult patients showed a 3.90% prevalence of malignancy among ITNs on thoracic contrast-enhanced CT. That study showed no CT feature that can reliably differentiate benign from malignant thyroid nodules. Therefore, the authors suggested that the US is a functional adjunctive test for evaluating incidentally detected thyroid abnormalities on CT ( 5 ). Our study saw 109 patients with one nodule and 129 with multiple nodules requiring biopsy. However, only 115 of 238 patients with biopsy indications had thyroid FNAB. Bilateral total thyroidectomy was performed in 6 patients with a giant nodule and four patients whose thyroid FNAB resulted in follicular neoplasia or was suspected of follicular neoplasia. Histopathologically, papillary thyroid cancer was detected in 3, and a well-differentiated thyroid tumor with uncertain malignant potential was detected in one patient. If we extrapolate from other CT series, we expected that 5% of the nodules we noticed would be cancer. In our study, malignancy was found in 0.30% (4/1343) of ITNs on CT and 3.48% (4/115) of patients who underwent a biopsy. The lower malignancy rate in our study might be related to the lack of FNAB results in nearly half of the patients with biopsy indication. The mean age of the patients who underwent a biopsy was 56 years. In addition, the difference in the mean age in the studies may also be a reason for the different results ( 9 , 14 ). Regarding thyroid functional status, being euthyroid was associated with improved survival. In critical situations, low thyroid hormone levels at the hypothalamic and peripheral tissue levels are considered compensatory. In patients with severe systemic disease, non-thyroidal illness syndrome is associated with increased mortality and morbidity and indicates a poor prognosis ( 15 , 16 ). Our study also showed that mortality was significantly increased in patients with non-thyroidal illness syndrome. Overt hypo/hyperthyroidism and subclinical hypo/hyperthyroidism were not associated with survival. The small number of patients in these groups may have affected the results. There are certain limitations of our study which should be addressed. First, the study's retrospective nature is not ideal for obtaining a random sample but allows a time-efficient review of many cases. Second, due to the effect of the pandemic on the reports' rapid conclusion, extrapulmonary pathologies may not have been paid attention too. Third, the clinical presentations of the patients were not similar, as the physicians reporting the CT and the US were not fixed. Fourth, no comments regarding thyroid were made on about 90% of the patients in the CT reports. It would have been possible to determine both benign and malignant nodules if more evaluation of thyroid nodules had been made in the CT reports. Our study is the first study on ITNs during the covid pandemic. Furthermore, it is the first to reach the number of patients examined in this amount. In addition, we evaluated not only the prevalence of ITNs but also the follow-up data of the patients. In conclusion, increased use of thoracic CT during Covid 19 pandemic probably caused increased detection of ITNs. In this large-scale study, the prevalence of thyroid nodules reported in thoracic CT was 3.82%, and thyroid cancer was detected in 1.30% of patients evaluated in the US. Therefore, Thoracic CT scans taken for different reasons might provide the opportunity for early diagnosis and treatment of thyroid cancers. Consequently, it is essential for those who evaluate CT scans not only to focus on the primary disease but also to check other regions for detecting such pathologies. Declarations Conflict of interest The authors declare that they have no conflict of interest. In addition, the authors have no financial relationship with the companies that manufactured the materials used in this study. Ethical approval All procedures performed in studies involving human participants were by the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. Informed consent Informed consent was obtained from all participants included in the study. References Goncalves S et al Artificial intelligence for early diagnosis of lung cancer through incidental nodule detection in low- and middle-income countries-acceleration during the COVID-19 pandemic but here to stay.Am J Cancer Res. 2022 Jan15;12(1):1–16. PMID: 35141002; PMCID: PMC8822269. Ahmed S et al (2012) Prevalence of unsuspected thyroid nodules in adults on contrast enhanced 16- and 64-MDCT of the chest. World J Radiol 4:311–317 Frank L, Quint LE (2012) Chest CT incidentalomas: thyroid lesions, enlarged mediastinal lymph nodes, and lung nodules. Cancer Imaging. Mar 5;12(1):41 – 8. doi: 10.1102/1470-7330.2012.0006 . PMID: 22391408; PMCID: PMC3335330 Hoang JK et al (2014) High variability in radiologists' reporting practices for incidental thyroid nodules detected on CT and MRI. AJNR Am J Neuroradiol 35:1190 – 94 Smith-Bindman R et al (2013) Risk of thyroid cancer based on thyroid ultrasound imaging characteristics: results of a population-based study. JAMA Intern Med 173:1788 – 96 Davies L, Welch HG (2014) Current thyroid cancer trends in the United States. JAMA Otolaryngol Head Neck Surg 140:317–322 Ito Y et al (2010) An observational trial for papillary thyroid microcarcinoma in Japanese patients. World J Surg 34:28 – 35 Ezzat S, Sarti DA, Cain DR, Braunstein GD (1994) Thyroid incidentalomas. Prevalence by palpation and ultrasonography. Arch Intern Med 154:1838–1840 Shetty SK et al (2006) Significance of incidental thyroid lesions detected on CT: correlation among CT, sonography, and pathology. AJR Am J Roentgenol 187:1349–1356 Cooper DS et al (2006) Management guidelines for patients with thyroid nodules and differentiated thyroid cancer. Thyroid 16:109–142 British Thyroid Association. British Thyroid Association guidelines for the management of thyroid cancer. Available from: URL: http://www.british-thyroid-association.org/Guidelines Johnson PT et al (2011) Common incidental findings on MDCT: survey of radiologist recommendations for patient management. J Am Coll Radiol 8:762–767 [PubMed] [Google Scholar] Nguyen XV et al (2013) Incidental thyroid nodules on CT: evaluation of 2 risk-categorization methods for workup of nodules. AJNR 34:1812–1817 Lin HW et al (2009) Survival impact of treatment options for papillary microcarcinoma of the thyroid. Laryngoscope 119:1983–1987 Forestier E et al (2009) Increased reverse triiodothyronine is associated with shorter survival in independently-living elderly: the Alsanut study. Eur J Endocrinol 160:207–214 Peeters RP et al (2005) Serum 3,3',5’-triiodothyronine (rT3) and 3,5,3’-triiodothyronine/rT3 are prognostic markers in critically ill patients and are associated with postmortem tissue deiodinase activities. J Clin Endocrinol Metab 90:4559–4565 Cite Share Download PDF Status: Published Journal Publication published 16 Dec, 2023 Read the published version in Hormones → Version 1 posted Editorial decision: Major revisions 30 Jun, 2023 Reviewers agreed at journal 13 May, 2023 Reviewers invited by journal 08 May, 2023 Editor invited by journal 02 May, 2023 Editor assigned by journal 01 May, 2023 First submitted to journal 01 May, 2023 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-2876461\",\"acceptedTermsAndConditions\":true,\"allowDirectSubmit\":false,\"archivedVersions\":[],\"articleType\":\"Research Article\",\"associatedPublications\":[],\"authors\":[{\"id\":198242608,\"identity\":\"cdf7d934-f358-4976-9b4f-611b0c5c9931\",\"order_by\":0,\"name\":\"Burcak Cavnar 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Fakultesi\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Oya\",\"middleName\":\"\",\"lastName\":\"Topaloglu\",\"suffix\":\"\"},{\"id\":198242615,\"identity\":\"abf678c4-ee3b-488b-b4df-53a89ef9c4e2\",\"order_by\":7,\"name\":\"Reyhan Ersoy\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"Ankara Yildirim Beyazit University Faculty of Medicine: Ankara Yildirim Beyazit Universitesi Tip Fakultesi\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Reyhan\",\"middleName\":\"\",\"lastName\":\"Ersoy\",\"suffix\":\"\"},{\"id\":198242616,\"identity\":\"a5315fbe-1152-4fdf-8598-0cfe3f5dfa44\",\"order_by\":8,\"name\":\"Bekir Cakir\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"Ankara Yildirim Beyazit University Faculty of Medicine: Ankara Yildirim Beyazit Universitesi Tip Fakultesi\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Bekir\",\"middleName\":\"\",\"lastName\":\"Cakir\",\"suffix\":\"\"}],\"badges\":[],\"createdAt\":\"2023-04-29 13:05:47\",\"currentVersionCode\":1,\"declarations\":\"\",\"doi\":\"10.21203/rs.3.rs-2876461/v1\",\"doiUrl\":\"https://doi.org/10.21203/rs.3.rs-2876461/v1\",\"draftVersion\":[],\"editorialEvents\":[{\"content\":\"https://doi.org/10.1007/s42000-023-00516-9\",\"type\":\"published\",\"date\":\"2023-12-16T15:01:48+00:00\"}],\"editorialNote\":\"\",\"failedWorkflow\":false,\"files\":[{\"id\":36786488,\"identity\":\"e10d4c33-209a-4889-9077-3f04ca683670\",\"added_by\":\"auto\",\"created_at\":\"2023-05-10 17:48:22\",\"extension\":\"png\",\"order_by\":1,\"title\":\"Figure 1\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":22294,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eThe flowchart of the study protocol\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"1.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-2876461/v1/a46a099bd057354a5c86386f.png\"},{\"id\":48401586,\"identity\":\"c3027c15-2df4-45ae-a202-85412e6085ca\",\"added_by\":\"auto\",\"created_at\":\"2023-12-18 15:11:05\",\"extension\":\"pdf\",\"order_by\":0,\"title\":\"\",\"display\":\"\",\"copyAsset\":false,\"role\":\"manuscript-pdf\",\"size\":292488,\"visible\":true,\"origin\":\"\",\"legend\":\"\",\"description\":\"\",\"filename\":\"manuscript.pdf\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-2876461/v1/e073e9d3-271d-4877-a5b9-4612cdf7b18a.pdf\"}],\"financialInterests\":\"\",\"formattedTitle\":\"Incidental thyroid nodules on Covid 19-related thoracic tomography scans: A giant cohort\",\"fulltext\":[{\"header\":\"INTRODUCTION\",\"content\":\"\\u003cp\\u003e \\u003cem\\u003eCoronavirus\\u003c/em\\u003e disease (\\u003cem\\u003eCOVID\\u003c/em\\u003e-\\u003cem\\u003e19\\u003c/em\\u003e) is an infectious disease caused by the SARS-CoV-2 virus. COVID-19 has spread rapidly since Dec 31, 2019, the first official case date in the world. During the SARS-CoV-2 pandemic, many multifaceted health problems, such as deaths from the disease, prolonged stay in hospital and/or intensive care, and long-term covid-related and psychological issues associated with quarantines and isolation, were experienced. In addition, forced negligence of non-covid-related disorders, such as postponing elective surgeries, delays in screening programs, and routine follow-up visits, also caused significant morbidity, defined as \\\"collateral damage.\\\" Last but not least, computerized thoracic tomography (CT) imaging was extensively employed, especially in the early era of the pandemic. While this increase in imaging studies is associated with radiation exposure, some epiphanies, such as the early detection of small lung cancers, have also been encountered (\\u003cspan citationid=\\\"CR1\\\" class=\\\"CitationRef\\\"\\u003e1\\u003c/span\\u003e).\\u003c/p\\u003e \\u003cp\\u003eAn incidental thyroid nodule (ITN) is defined as a nodule not previously detected or suspected clinically but identified by an imaging study. The prevalence of ITN on thoracic CT in the adult population is 16\\u0026ndash;25% (\\u003cspan citationid=\\\"CR1\\\" class=\\\"CitationRef\\\"\\u003e1\\u003c/span\\u003e, \\u003cspan citationid=\\\"CR2\\\" class=\\\"CitationRef\\\"\\u003e2\\u003c/span\\u003e). Most ITNs are benign and small. Additionally, it is usually slow-growing even if an incidental thyroid malignancy is detected. Nevertheless, it should not be ignored that some types can show an aggressive course.\\u003c/p\\u003e \\u003cp\\u003eOn the other hand, current practice for reporting thyroid nodules on CT and magnetic resonance imaging (MRI) by radiologists is highly variable. Some radiologists may notify all ITNs because of the possibility of malignancy. Others may not report any ITN thinking that thyroid cancers in ITNs are relatively rare and small thyroid cancers usually take an indolent course (\\u003cspan additionalcitationids=\\\"CR4 CR5\\\" citationid=\\\"CR3\\\" class=\\\"CitationRef\\\"\\u003e3\\u003c/span\\u003e\\u0026ndash;\\u003cspan citationid=\\\"CR6\\\" class=\\\"CitationRef\\\"\\u003e6\\u003c/span\\u003e). \\u003cem\\u003eImaging films may be reported focused on answering the primary clinical question and not scrutinized for the presence of coincidental pathologies or lesions. T\\u003c/em\\u003ehe necessity of being fast in diagnosis and treatment due to the nature of the pandemic has made diagnosing and treating thyroid cancer more complicated.\\u003c/p\\u003e \\u003cp\\u003eThis study aimed to determine the incidence of thyroid nodules incidentally detected in thoracic CTs for the suspicion of Covid-19 pneumonia.\\u003c/p\\u003e\"},{\"header\":\"MATERIALS AND METHODS\",\"content\":\"\\u003cp\\u003eAdult patients who underwent thoracic CT in our hospital for Covid-19 management between March 2020 and September 2020 were retrospectively identified. Medical information registered in the hospital and national health system were reviewed. The prevalence of incidental thyroid nodules at CT, thyroid function test results of patients with incidental lesions, correlation of CT findings with ultrasonography (US) findings, and fine-needle aspiration biopsy (FNAB) results were evaluated. Patients younger than 18 years old were excluded. Those with a known thyroid disease and a history of previous thyroid operation or radiotherapy to the head and neck region were also excluded. After removing repetitions, there remained 36.939 adult patients with a CT scan. Among these, 624 had a previous history of thyroid operation, and 1201 had already been diagnosed with a thyroid pathology. The final analysis included 35.113 patients. There was information about the thyroid gland in CT reports of 3049 patients. They were classified as 1) those with ITN, 2) those with thyroid heterogeneity, and 3) those without thyroid pathology. (The flowchart of the study protocol is given in Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig1\\\" class=\\\"InternalRef\\\"\\u003e1\\u003c/span\\u003e.)\\u003c/p\\u003e \\u003cp\\u003eThoracic CT scans were evaluated and reported by different radiologists. We did a text search for \\\"thyroid nodule\\\" OR \\\"thyroid\\\" OR \\\"thyroid heterogeneity\\\" OR \\\"calcification\\\" in all CT imaging reports. The presence of thyroid nodules or thyroid heterogeneity in the CT report was accepted as thyroid pathology. Thyrotrophin (TSH), free triiodothyronine (fT3), free thyroxine (fT4), antithyroid peroxidase antibody (anti-TPO), antithyroglobulin antibody (anti-Tg), and calcitonin values of patients with thyroid pathology were scanned. Thyroid function tests were performed within three months after CT scans were evaluated. Chemiluminescence methods (Immulite 1000, Immulite 2000, Immulite 2000 XPi Siemens Healthineers Headquarters, Siemens Healthcare GmbH Henkestr. 127 91052 Erlangen, Germany) were used for measurement of serum levels of TSH, fT3, and fT4, anti-TPO, and anti-Tg. The normal ranges for TSH, fT3, fT4, anti-TPO, anti-Tg, and calcitonin were 0.4 to 4 mIU/mL, 2.3 to 4.2 pg/mL, 0.89 to 1.76 ng/dL, 0 to 60 IU/mL, 0 to 1.3 IU/mL, and 0 to 5 ng/L respectively. The thyroid antibody levels greater than the upper range were accepted as positive. An abnormally high TSH with low fT3 and fT4 levels means hypothyroidism. An unusually low TSH with high fT3 and fT4 levels means hyperthyroidism.\\u003c/p\\u003e \\u003cp\\u003eUS after CT was performed in endocrinology or radiology departments. Thyroid FNAB was evaluated according to the Bethesda classification. It defined the reporting system into six different diagnostic criteria, with each having a different risk of malignancy: (i) non-diagnostic or unsatisfactory; (ii) benign; (iii) atypia of undetermined significance (AUS) or follicular lesion of undetermined significance (FLUS); (iv) follicular neoplasm or suspicious for a follicular neoplasm; (v) suspicious for malignancy; and (vi) malignant. As determined by surgical pathology, the risk of malignancy is estimated in each category and used to guide treatment decisions with ongoing clinical observation or surgical resection.\\u003c/p\\u003e \\u003cp\\u003eData were entered into an Excel spreadsheet (2013; Microsoft, Redmond, Washington). Shapiro-Wilk's test and normality graphs examined the distributions of continuous variables. All continuous variables were summarized by median (range), whereas categorical variables were reported as frequency (%). In addition, Mann-Whitney U and chi-square tests were performed to compare continuous and categorical variables, respectively. All statistical analyses were performed via IBM SPSS Statistics version 21.0. (IBM Corp, IBM SPSS Statistics for Windows, Armonk, NY). A \\u003cem\\u003eP value\\u003c/em\\u003e\\u0026thinsp;\\u0026lt;\\u0026thinsp;.05 was considered statistically significant.\\u003c/p\\u003e \\u003cp\\u003e The local ethical committee approved the study protocol (Aug 19, 2020 \\u0026ndash; E1-20-872).\\u003c/p\\u003e\"},{\"header\":\"RESULTS\",\"content\":\"\\u003cp\\u003eThe data of 35.113 patients were analyzed. There were 20294 male (57.70%) and 14819 (42.30%) female subjects with a mean age of 48\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;18 (19\\u0026ndash;102). The prevalence of ITN was 3.82% (1343/35113 patients), and thyroid heterogeneity was 1.11% (388/35113 patients). While it was explicitly stated that no pathology was found in the thyroid gland in 3.75% (1318/35113) of the patients, no information was given about the thyroid gland in 91.32% (32064/35113) of the patients (Table\\u0026nbsp;\\u003cspan refid=\\\"Tab1\\\" class=\\\"InternalRef\\\"\\u003e1\\u003c/span\\u003e). Thus, the number of patients informed about the thyroid was 3049 (8.68%), and the number of patients with thyroid pathology was 1731 (4.93%).\\u003c/p\\u003e \\u003cp\\u003e \\u003cdiv class=\\\"gridtable\\\"\\u003e\\u003ctable float=\\\"Yes\\\" id=\\\"Tab1\\\" border=\\\"1\\\"\\u003e \\u003ccaption language=\\\"En\\\"\\u003e \\u003cdiv class=\\\"CaptionNumber\\\"\\u003eTable 1\\u003c/div\\u003e \\u003cdiv class=\\\"CaptionContent\\\"\\u003e \\u003cp\\u003eThyroid gland findings on thoracic computed tomography\\u003c/p\\u003e \\u003c/div\\u003e \\u003c/caption\\u003e \\u003ccolgroup cols=\\\"3\\\"\\u003e \\u003cdiv align=\\\"left\\\" class=\\\"colspec\\\" colname=\\\"c1\\\" colnum=\\\"1\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"char\\\" char=\\\".\\\" class=\\\"colspec\\\" colname=\\\"c2\\\" colnum=\\\"2\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"char\\\" char=\\\".\\\" class=\\\"colspec\\\" colname=\\\"c3\\\" colnum=\\\"3\\\"\\u003e\\u003c/div\\u003e \\u003cthead\\u003e \\u003ctr\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c1\\\"\\u003e\\u0026nbsp;\\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003eFrequency\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003ePercent (%)\\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\\u003eNo pathology\\u003c/b\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e1318\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e3.75\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003eHeterogenous thyroid\\u003c/b\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e388\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e1.11\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003eThyroid nodule\\u003c/b\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e1343\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e3.82\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003eNo information about thyroid\\u003c/b\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e32064\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e91.32\\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 age of patients with thyroid pathology on thoracic CT was 63\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;15, and the mean age of patients without thyroid pathology was 53\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;15 (p\\u0026thinsp;\\u0026lt;\\u0026thinsp;0.001). In addition, thyroid pathology was more frequent in female subjects than male subjects (42.10% vs. 57.90% p\\u0026thinsp;\\u0026lt;\\u0026thinsp;0.001). 96 of 162 (59.20%) female patients and 29 of 72 (40.20%) male patients had multiple nodules (p\\u0026thinsp;=\\u0026thinsp;0.007). However, there was no statistically significant relationship between age and having single or multiple nodules (p\\u0026thinsp;=\\u0026thinsp;0.561), with the mean age of patients with solitary nodules being 60\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;13 and multiple nodules being 61\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;13.\\u003c/p\\u003e \\u003cp\\u003eA thyroid function test was performed on 1271 (73.40%) patients with thyroid pathology on CT. Of the patients, 902 (70.96%) were evaluated as euthyroid, 49 (3.85%) as overt hypothyroidism, 5 (0.39%) as subclinical hypothyroidism, 167 (13.13%) as subclinical hyperthyroidism, 22 (1.73%) as overt hyperthyroidism and 128 (10.07%) as non-thyroidal illness syndrome. Anti-TPO was positive in 241 (61.79%) of 390 patients tested for antibodies. Anti-Tg was positive in 127 (%38.36) of 331 patients who were tested for antibodies. Calcitonin value was evaluated in 124 (9.85%) patients; only six had results above the reference range. In the outpatient clinic follow-ups, seven patients were diagnosed with Graves disease, 2 with toxic adenoma, and 3 with toxic multinodular goiter.\\u003c/p\\u003e \\u003cp\\u003eOf 1731 patients with thyroid pathology on CT, 439 died due to Covid-19 infection. Thyroid function tests were available in 293 patients who died and 978 patients who survived. Euthyroidism was detected in 902 patients. In addition, there were 128 patients with non-thyroidal illness syndrome. Hypothyroidism and hyperthyroidism were observed in 52 and 189 patients, respectively. Mortality rates according to thyroid function status are presented in Table\\u0026nbsp;\\u003cspan refid=\\\"Tab2\\\" class=\\\"InternalRef\\\"\\u003e2\\u003c/span\\u003e. When euthyroid patients were compared with non-euthyroid patients, the former group had better survival (16.51% vs. 39.02%, p\\u0026thinsp;\\u0026lt;\\u0026thinsp;0.001). Mortality was higher in patients with non-thyroidal illness syndrome compared to euthyroid subjects (62.50% vs. 16.51%, p\\u0026thinsp;\\u0026lt;\\u0026thinsp;0.001). A pairwise Kruskall-Wallis analysis did not demonstrate an association between overt or subclinical hypothyroidism and hyperthyroidism with survival (p\\u0026thinsp;\\u0026gt;\\u0026thinsp;0.05).\\u003c/p\\u003e \\u003cp\\u003e \\u003cdiv class=\\\"gridtable\\\"\\u003e\\u003ctable float=\\\"Yes\\\" id=\\\"Tab2\\\" border=\\\"1\\\"\\u003e \\u003ccaption language=\\\"En\\\"\\u003e \\u003cdiv class=\\\"CaptionNumber\\\"\\u003eTable 2\\u003c/div\\u003e \\u003cdiv class=\\\"CaptionContent\\\"\\u003e \\u003cp\\u003eMortality according to thyroid functional status\\u003c/p\\u003e \\u003c/div\\u003e \\u003c/caption\\u003e \\u003ccolgroup cols=\\\"4\\\"\\u003e \\u003cdiv align=\\\"left\\\" class=\\\"colspec\\\" colname=\\\"c1\\\" colnum=\\\"1\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"char\\\" char=\\\".\\\" class=\\\"colspec\\\" colname=\\\"c2\\\" colnum=\\\"2\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"char\\\" char=\\\".\\\" class=\\\"colspec\\\" colname=\\\"c3\\\" colnum=\\\"3\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"char\\\" char=\\\".\\\" class=\\\"colspec\\\" colname=\\\"c4\\\" colnum=\\\"4\\\"\\u003e\\u003c/div\\u003e \\u003cthead\\u003e \\u003ctr\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c1\\\"\\u003e\\u0026nbsp;\\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003eExitus\\u003c/p\\u003e \\u003cp\\u003en\\u0026thinsp;=\\u0026thinsp;293 (%)\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003eSurvivor\\u003c/p\\u003e \\u003cp\\u003en\\u0026thinsp;=\\u0026thinsp;978 (%)\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003eP value\\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\\u003eNon-Thyroidal Illness Syndrome\\u003c/b\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e80 (18.22%)\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e48 (3.72%)\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e\\u0026lt;\\u0026thinsp;0.001\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003eEuthyroidism\\u003c/b\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e149 (50.85%)\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e753 (76.99%)\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\".\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e\\u0026lt;\\u0026thinsp;0.001\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003eHypothyroidism\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003eSubclinical\\u003c/p\\u003e \\u003cp\\u003eOvert\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e2 (0.68%)\\u003c/p\\u003e \\u003cp\\u003e6 (2.04%)\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e3 (0.30%)\\u003c/p\\u003e \\u003cp\\u003e41 (4.19%)\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e.367\\u003c/p\\u003e \\u003cp\\u003e.087\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003eHyperthyroidism\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003eSubclinical\\u003c/p\\u003e \\u003cp\\u003eOvert\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e48 (16.38%)\\u003c/p\\u003e \\u003cp\\u003e8 (2.73%)\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e119 (12.16%)\\u003c/p\\u003e \\u003cp\\u003e14 (1.43%)\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e.061\\u003c/p\\u003e \\u003cp\\u003e.974\\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\\u003eRadiologists have recommended thyroid US for every patient with thyroid pathology. When medical records of the hospital and national health system were examined, it was observed that 308 of 1731 (17.80%) patients had follow-up thyroid US. It was performed in another hospital in 27 (8.77%) and our hospital in 281 (91.23%) patients. Thyroid pathology was not detected in the US in 8 (2.59%) patients on CT. Ultrasonographically, there was chronic thyroiditis without nodule in 28 (9.09%), nodular goiter in 26 (8.44%), and multinodular goiter in 246 (79.87%) patients.\\u003c/p\\u003e \\u003cp\\u003eBecause different physicians performed US, localization and features of nodules were also defined differently. An FNAB was indicated in 238 (87.50%) patients. While 109 (40.07%) patients had a single nodule with FNAB indication, 129 (59.92%) had more than one nodule that needed to be evaluated by FNAB. Of the 238 patients with biopsy indication, only 115 (48.31%) underwent a thyroid FNAB, and the mean age of these patients was 56.18\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;13.21 [SD] years. The cytological diagnosis was benign in 59 (51.30%), non-diagnostic in 30 (26.08%), atypia of uncertain significance in 22 (19.13%), suspected follicular neoplasia/follicular neoplasia in 4 (3.46%) patients. Re-biopsy was recommended for 30 patients with non-diagnostic cytology and 22 patients with atypia of uncertain significance cytology. All patients with follicular neoplasia/suspected follicular neoplasia underwent thyroidectomy, and histopathological diagnosis was follicular adenoma in 2, benign nodular disease in 1, and well-differentiated thyroid tumor with uncertain malignant potential in 1 patient. Thyroidectomy was performed in six more patients due to giant nodules, and the final diagnosis was benign in 2 and papillary thyroid cancer in 3 patients. At the same time, we could not reach the result for one patient operated on in another clinic. Operation indications and histopathological diagnosis are summarized in Table \\u003cspan refid=\\\"Tab3\\\" class=\\\"InternalRef\\\"\\u003e3\\u003c/span\\u003e. Malignancy rates were 0.30% (4/1343) in patients with ITNs on CT, 1.30% (4/308) in patients evaluated with the US, and 3.47% (4/115) in patients who underwent a biopsy.\\u003c/p\\u003e \\u003cp\\u003e \\u003cdiv class=\\\"gridtable\\\"\\u003e\\u003ctable float=\\\"Yes\\\" id=\\\"Tab3\\\" border=\\\"1\\\"\\u003e \\u003ccaption language=\\\"En\\\"\\u003e \\u003cdiv class=\\\"CaptionNumber\\\"\\u003eTable 3\\u003c/div\\u003e \\u003cdiv class=\\\"CaptionContent\\\"\\u003e \\u003cp\\u003eThyroidectomy indications and histopathological results\\u003c/p\\u003e \\u003c/div\\u003e \\u003c/caption\\u003e \\u003ccolgroup cols=\\\"3\\\"\\u003e \\u003cdiv align=\\\"left\\\" class=\\\"colspec\\\" colname=\\\"c1\\\" colnum=\\\"1\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"left\\\" class=\\\"colspec\\\" colname=\\\"c2\\\" colnum=\\\"2\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"left\\\" class=\\\"colspec\\\" colname=\\\"c3\\\" colnum=\\\"3\\\"\\u003e\\u003c/div\\u003e \\u003cthead\\u003e \\u003ctr\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c1\\\"\\u003e\\u0026nbsp;\\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003eIndication\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003eHistopathology\\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\\u003ePatient 1\\u003c/b\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003eFNAB resulted in follicular neoplasia\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003eBenign\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003ePatient 2\\u003c/b\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003eFNAB resulted in follicular neoplasia\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003eFollicular adenoma\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003ePatient 3\\u003c/b\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003eFNAB resulted in follicular neoplasia\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003eFollicular adenoma\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003ePatient 4\\u003c/b\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003eFNAB resulted as suspicious for follicular neoplasia\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003eWell-differentiated thyroid tumor with uncertain malignant potential\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003ePatient 5\\u003c/b\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003eGiant nodule\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003eBenign\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003ePatient 6\\u003c/b\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003eGiant nodule\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003eBenign\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003ePatient 7\\u003c/b\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003eGiant nodule\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003ePapillary microcarcinoma\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003ePatient 8\\u003c/b\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003eGiant nodule\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003ePapillary microcarcinoma\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003ePatient 9\\u003c/b\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003eGiant nodule\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003ePapillary carcinoma\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e\\u003cb\\u003ePatient 10\\u003c/b\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003eGiant nodule\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003eUnknown result\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003c/tbody\\u003e \\u003c/colgroup\\u003e \\u003c/table\\u003e\\u003c/div\\u003e \\u003c/p\\u003e\"},{\"header\":\"DISCUSSION\",\"content\":\"\\u003cp\\u003eCT is the most common imaging modality in which ITNs are detected (\\u003cspan citationid=\\\"CR7\\\" class=\\\"CitationRef\\\"\\u003e7\\u003c/span\\u003e). Mainly because of the wide availability of thoracic CT to evaluate various medical conditions, the discovery of ITNs is steadily increasing. At the same time, the Covid-19 pandemic undoubtedly further contributed to this increment. Especially in the early days of the pandemic, the use of CT had significantly increased since PCR diagnostic tests did not have sufficient sensitivity, and chest X-rays did not make an early diagnosis. Theoretically, increasing CT scans may be associated with an increased incidence of ITNs. However, in practice, due to the nature of the pandemic, thoracic CT scans are evaluated by different radiologists and reported quickly. Thus, sufficient information about the thyroid gland may not be given in the CT reports. Our study showed that the prevalence of thyroid heterogeneity was 1.10%, and ITNs were 3.80% on thoracic CT in the adult population. Our finding is much less than the prevalence of 25.10% reported in 2012 by Ahmed et al. (\\u003cspan citationid=\\\"CR2\\\" class=\\\"CitationRef\\\"\\u003e2\\u003c/span\\u003e), who evaluated 3077 consecutive adult patients in their recent study. They found age as the most critical determinant of the significance of ITNs on thoracic CT. While the mean age of the patients included in their study was 59.30, in our study, the mean age was 48.23. Although approximately 24000 thoracic CT scans were taken in six months in our hospital in the pre-pandemic period, this number reached about 38000 in the first six months of the pandemic period. Another reason for the lower prevalence in our study compared to previous studies might be this increased number of CT scans which needed to be reported faster due to the nature of the pandemic by the same number of radiologists. In addition, technical differences such as the image quality of the CT, using intravenous contrast, and taking thin sections of the image might also cause different prevalences in different studies.\\u003c/p\\u003e \\u003cp\\u003eIn the study by Ahmed et al., in addition to age, female gender was also associated with thyroid nodules detected in CT (\\u003cspan citationid=\\\"CR2\\\" class=\\\"CitationRef\\\"\\u003e2\\u003c/span\\u003e). However, in the study by Ezzat S. et al., they did not find a correlation between age and nodule frequency (\\u003cspan citationid=\\\"CR8\\\" class=\\\"CitationRef\\\"\\u003e8\\u003c/span\\u003e). Like the Ahmed et al. study, the female gender was associated with our study's nodules and multiple nodules.\\u003c/p\\u003e \\u003cp\\u003eMajor sets of guidelines for the follow-up and management of ITNs are established by the American Thyroid Association (ATA) and the British Thyroid Association (\\u003cspan citationid=\\\"CR10\\\" class=\\\"CitationRef\\\"\\u003e10\\u003c/span\\u003e, \\u003cspan citationid=\\\"CR11\\\" class=\\\"CitationRef\\\"\\u003e11\\u003c/span\\u003e). Although it is proposed that patients with ITNs larger than 1 cm undergo US for further evaluation in some guidelines (\\u003cspan citationid=\\\"CR12\\\" class=\\\"CitationRef\\\"\\u003e12\\u003c/span\\u003e), it was reported that utilizing a three-component grading system that stratifies nodules according to risk increases diagnostic accuracy in the study by Nguyen et al. (\\u003cspan citationid=\\\"CR13\\\" class=\\\"CitationRef\\\"\\u003e13\\u003c/span\\u003e). They compared the performance of 2 risk-categorization methods of selecting CT-detected ITNs for workup. Method A was based simply on nodule size. They made the 3-tiered system for ITNs malignancy risk evaluation for method B: Risk category 1 is a nodule of any size with aggressive imaging features of invasive (such as local invasion, suspicious lymphadenopathy) or metastatic disease. Risk category 2 is a nodule of any size in a patient younger than 35 years of age and not meeting the criteria for risk category 1. Risk category 3 is a nodule at or above a cutoff of 15 mm and not meeting the criteria for categories 1 and 2. The 15-mm cutoff is intended to reflect a higher size threshold for the workup of nodules that lack aggressive imaging findings or demographic risk factors. The purpose of having three risk categories is to help the radiologist communicate the risk of malignancy in a CT-detected ITN and the need for further investigation by sonography. Compared with the common practice of a 10-mm-size cutoff, the 3-tiered system reduces excess workup of benign ITNs while capturing the same proportion of thyroid malignancies and is no more likely to miss high-mortality malignancies. While it would be ideal for a categorization method not to miss all incidental thyroid malignancies, it may be more rational and cost-effective to capture all malignancies associated with poor outcomes.\\u003c/p\\u003e \\u003cp\\u003eAlthough most thyroid nodules were benign by cytological and histopathological evaluations, thyroid malignancies were also detected in our study population. Despite relatively low (about 5%) cancer risk, most nodules 1 cm or greater are sampled with US-guided FNAB. This situation might cause a marked increase in papillary microcarcinomas (\\u003cspan citationid=\\\"CR13\\\" class=\\\"CitationRef\\\"\\u003e13\\u003c/span\\u003e). A previous study of adult patients showed a 3.90% prevalence of malignancy among ITNs on thoracic contrast-enhanced CT. That study showed no CT feature that can reliably differentiate benign from malignant thyroid nodules. Therefore, the authors suggested that the US is a functional adjunctive test for evaluating incidentally detected thyroid abnormalities on CT (\\u003cspan citationid=\\\"CR5\\\" class=\\\"CitationRef\\\"\\u003e5\\u003c/span\\u003e). Our study saw 109 patients with one nodule and 129 with multiple nodules requiring biopsy. However, only 115 of 238 patients with biopsy indications had thyroid FNAB. Bilateral total thyroidectomy was performed in 6 patients with a giant nodule and four patients whose thyroid FNAB resulted in follicular neoplasia or was suspected of follicular neoplasia. Histopathologically, papillary thyroid cancer was detected in 3, and a well-differentiated thyroid tumor with uncertain malignant potential was detected in one patient. If we extrapolate from other CT series, we expected that 5% of the nodules we noticed would be cancer. In our study, malignancy was found in 0.30% (4/1343) of ITNs on CT and 3.48% (4/115) of patients who underwent a biopsy. The lower malignancy rate in our study might be related to the lack of FNAB results in nearly half of the patients with biopsy indication. The mean age of the patients who underwent a biopsy was 56 years. In addition, the difference in the mean age in the studies may also be a reason for the different results (\\u003cspan citationid=\\\"CR9\\\" class=\\\"CitationRef\\\"\\u003e9\\u003c/span\\u003e, \\u003cspan citationid=\\\"CR14\\\" class=\\\"CitationRef\\\"\\u003e14\\u003c/span\\u003e).\\u003c/p\\u003e \\u003cp\\u003eRegarding thyroid functional status, being euthyroid was associated with improved survival. In critical situations, low thyroid hormone levels at the hypothalamic and peripheral tissue levels are considered compensatory. In patients with severe systemic disease, non-thyroidal illness syndrome is associated with increased mortality and morbidity and indicates a poor prognosis (\\u003cspan citationid=\\\"CR15\\\" class=\\\"CitationRef\\\"\\u003e15\\u003c/span\\u003e, \\u003cspan citationid=\\\"CR16\\\" class=\\\"CitationRef\\\"\\u003e16\\u003c/span\\u003e). Our study also showed that mortality was significantly increased in patients with non-thyroidal illness syndrome. Overt hypo/hyperthyroidism and subclinical hypo/hyperthyroidism were not associated with survival. The small number of patients in these groups may have affected the results.\\u003c/p\\u003e \\u003cp\\u003eThere are certain limitations of our study which should be addressed. First, the study's retrospective nature is not ideal for obtaining a random sample but allows a time-efficient review of many cases. Second, due to the effect of the pandemic on the reports' rapid conclusion, extrapulmonary pathologies may not have been paid attention too. Third, the clinical presentations of the patients were not similar, as the physicians reporting the CT and the US were not fixed. Fourth, no comments regarding thyroid were made on about 90% of the patients in the CT reports. It would have been possible to determine both benign and malignant nodules if more evaluation of thyroid nodules had been made in the CT reports.\\u003c/p\\u003e \\u003cp\\u003eOur study is the first study on ITNs during the covid pandemic. Furthermore, it is the first to reach the number of patients examined in this amount. In addition, we evaluated not only the prevalence of ITNs but also the follow-up data of the patients.\\u003c/p\\u003e \\u003cp\\u003eIn conclusion, increased use of thoracic CT during Covid 19 pandemic probably caused increased detection of ITNs. In this large-scale study, the prevalence of thyroid nodules reported in thoracic CT was 3.82%, and thyroid cancer was detected in 1.30% of patients evaluated in the US. Therefore, Thoracic CT scans taken for different reasons might provide the opportunity for early diagnosis and treatment of thyroid cancers. Consequently, it is essential for those who evaluate CT scans not only to focus on the primary disease but also to check other regions for detecting such pathologies.\\u003c/p\\u003e \\u003cp\\u003e \\u003c/p\\u003e\"},{\"header\":\"Declarations\",\"content\":\"\\u003cp\\u003e\\u003cstrong\\u003eConflict of interest\\u003c/strong\\u003e The authors declare that they have no conflict of interest. In addition, the authors have no financial relationship with the companies that manufactured the materials used in this study.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eEthical approval\\u003c/strong\\u003e All procedures performed in studies involving human participants were by the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eInformed consent\\u0026nbsp;\\u003c/strong\\u003eInformed consent was obtained from all participants included in the study.\\u003c/p\\u003e\"},{\"header\":\"References\",\"content\":\"\\u003col\\u003e\\u003cli\\u003e\\u003cspan\\u003eGoncalves S et al Artificial intelligence for early diagnosis of lung cancer through incidental nodule detection in low- and middle-income countries-acceleration during the COVID-19 pandemic but here to stay.Am J Cancer Res. 2022 Jan15;12(1):1\\u0026ndash;16. PMID: 35141002; PMCID: PMC8822269.\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eAhmed S et al (2012) Prevalence of unsuspected thyroid nodules in adults on contrast enhanced 16- and 64-MDCT of the chest. World J Radiol 4:311\\u0026ndash;317\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eFrank L, Quint LE (2012) Chest CT incidentalomas: thyroid lesions, enlarged mediastinal lymph nodes, and lung nodules. Cancer Imaging. Mar 5;12(1):41 \\u0026ndash; 8. doi: \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003e10.1102/1470-7330.2012.0006\\u003c/span\\u003e\\u003cspan address=\\\"10.1102/1470-7330.2012.0006\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e. PMID: 22391408; PMCID: PMC3335330\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eHoang JK et al (2014) High variability in radiologists' reporting practices for incidental thyroid nodules detected on CT and MRI. AJNR Am J Neuroradiol 35:1190 \\u0026ndash; 94\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eSmith-Bindman R et al (2013) Risk of thyroid cancer based on thyroid ultrasound imaging characteristics: results of a population-based study. JAMA Intern Med 173:1788 \\u0026ndash; 96\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eDavies L, Welch HG (2014) Current thyroid cancer trends in the United States. JAMA Otolaryngol Head Neck Surg 140:317\\u0026ndash;322\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eIto Y et al (2010) An observational trial for papillary thyroid microcarcinoma in Japanese patients. World J Surg 34:28 \\u0026ndash; 35\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eEzzat S, Sarti DA, Cain DR, Braunstein GD (1994) Thyroid incidentalomas. Prevalence by palpation and ultrasonography. Arch Intern Med 154:1838\\u0026ndash;1840\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eShetty SK et al (2006) Significance of incidental thyroid lesions detected on CT: correlation among CT, sonography, and pathology. AJR Am J Roentgenol 187:1349\\u0026ndash;1356\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eCooper DS et al (2006) Management guidelines for patients with thyroid nodules and differentiated thyroid cancer. Thyroid 16:109\\u0026ndash;142\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eBritish Thyroid Association. British Thyroid Association guidelines for the management of thyroid cancer. Available from: URL: \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003ehttp://www.british-thyroid-association.org/Guidelines\\u003c/span\\u003e\\u003cspan address=\\\"http://www.british-thyroid-association.org/Guidelines\\\" targettype=\\\"URL\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eJohnson PT et al (2011) Common incidental findings on MDCT: survey of radiologist recommendations for patient management. J Am Coll Radiol 8:762\\u0026ndash;767 [PubMed] [Google Scholar]\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eNguyen XV et al (2013) Incidental thyroid nodules on CT: evaluation of 2 risk-categorization methods for workup of nodules. AJNR 34:1812\\u0026ndash;1817\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eLin HW et al (2009) Survival impact of treatment options for papillary microcarcinoma of the thyroid. Laryngoscope 119:1983\\u0026ndash;1987\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eForestier E et al (2009) Increased reverse triiodothyronine is associated with shorter survival in independently-living elderly: the Alsanut study. Eur J Endocrinol 160:207\\u0026ndash;214\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003ePeeters RP et al (2005) Serum 3,3',5\\u0026rsquo;-triiodothyronine (rT3) and 3,5,3\\u0026rsquo;-triiodothyronine/rT3 are prognostic markers in critically ill patients and are associated with postmortem tissue deiodinase activities. J Clin Endocrinol Metab 90:4559\\u0026ndash;4565\\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\":true,\"isPdf\":false,\"isPdfUpToDate\":true,\"isWithdrawnOrRetracted\":false,\"journal\":{\"display\":true,\"email\":\"info@researchsquare.com\",\"identity\":\"hormones\",\"isNatureJournal\":false,\"hasQc\":true,\"allowDirectSubmit\":false,\"externalIdentity\":\"HORM\",\"sideBox\":\"Learn more about [Hormones](https://www.springer.com/journal/42000)\",\"snPcode\":\"42000\",\"submissionUrl\":\"https://www.editorialmanager.com/horm/default2.aspx\",\"title\":\"Hormones\",\"twitterHandle\":\"\",\"acdcEnabled\":true,\"dfaEnabled\":true,\"editorialSystem\":\"em\",\"reportingPortfolio\":\"Springer Hybrid\",\"inReviewEnabled\":true,\"inReviewRevisionsEnabled\":false},\"keywords\":\"incidental, thyroid nodules, pandemic, covid-19\",\"lastPublishedDoi\":\"10.21203/rs.3.rs-2876461/v1\",\"lastPublishedDoiUrl\":\"https://doi.org/10.21203/rs.3.rs-2876461/v1\",\"license\":{\"name\":\"CC BY 4.0\",\"url\":\"https://creativecommons.org/licenses/by/4.0/\"},\"manuscriptAbstract\":\"\\u003cp\\u003e\\u003cb\\u003eIntroduction:\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003eComputerized thoracic tomography (CT) imaging was extensively employed, especially in the early era of the \\u003cem\\u003eCoronavirus\\u003c/em\\u003e pandemic. An incidental thyroid nodule (ITN) is defined as a nodule not previously detected or suspected clinically but identified by an imaging study. This study aimed to determine the incidence of thyroid nodules incidentally detected in thoracic CTs for the suspicion of Covid-19 pneumonia.\\u003c/p\\u003e\\u003cp\\u003e\\u003cb\\u003eMaterials and methods\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003eAdult patients who underwent thoracic CT in our hospital for Covid-19 management between March 2020 and September 2020 were retrospectively identified. Medical information registered in the hospital and national health system were reviewed. The prevalence of incidental thyroid nodules at CT, thyroid function test results of patients with incidental lesions, correlation of CT findings with ultrasonography (US) findings, and fine-needle aspiration biopsy (FNAB) results were evaluated.\\u003c/p\\u003e\\u003cp\\u003e\\u003cb\\u003eResults\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003eWe determined 36.939 adult patients that had a CT scan. Among these, 624 had a previous history of thyroid operation, and 1201 had already been diagnosed with a thyroid pathology. The final analysis included 35.113 patients. There was information about the thyroid gland in CT reports of 3049 patients. The prevalence of ITN was 3.82% (1343/35113 patients), and thyroid heterogeneity was 1.11% (388/35113 patients). While it was explicitly stated that no pathology was found in the thyroid gland in 3.75% (1318/35113) of the patients, no information was given about the thyroid gland in 91.32% (32064/35113) of the patient. Thus, the number of patients informed about the thyroid was 3049 (8.68%), and the number of patients with thyroid pathology was 1731 (4.93%). It was observed that 308 of 1731 (17.80%) patients had follow-up thyroid US. An FNAB was indicated in 238 (87.50%) patients. Of the 238 patients with biopsy indication, only 115 (48.31%) underwent a thyroid FNAB. The cytological diagnosis was benign in 59 (51.30%), non-diagnostic in 30 (26.08%), atypia of uncertain significance in 22 (19.13%), suspected follicular neoplasia/follicular neoplasia in 4 (3.46%) patients. Thyroidectomy was performed in six more patients due to giant nodules, and the final diagnosis was benign in 2 and papillary thyroid cancer in 3 patients.\\u003c/p\\u003e\\u003cp\\u003e\\u003cb\\u003eConclusion\\u003c/b\\u003e\\u003c/p\\u003e \\u003cp\\u003eIn conclusion, increased use of thoracic CT during Covid 19 pandemic probably caused increased detection of ITNs. In this large-scale study, the prevalence of thyroid nodules reported in thoracic CT was 3.82%, and thyroid cancer was detected in 1.30% of patients evaluated in the US. Therefore, Thoracic CT scans taken for different reasons might provide the opportunity for early diagnosis and treatment of thyroid cancers.\\u003c/p\\u003e\",\"manuscriptTitle\":\"Incidental thyroid nodules on Covid 19-related thoracic tomography scans: A giant cohort\",\"msid\":\"\",\"msnumber\":\"\",\"nonDraftVersions\":[{\"code\":1,\"date\":\"2023-05-10 17:48:17\",\"doi\":\"10.21203/rs.3.rs-2876461/v1\",\"editorialEvents\":[{\"type\":\"communityComments\",\"content\":0},{\"type\":\"decision\",\"content\":\"Major revisions\",\"date\":\"2023-06-30T08:42:50+00:00\",\"index\":\"\",\"fulltext\":\"\"},{\"type\":\"reviewerAgreed\",\"content\":\"\",\"date\":\"2023-05-13T05:43:05+00:00\",\"index\":0,\"fulltext\":\"\"},{\"type\":\"reviewersInvited\",\"content\":\"\",\"date\":\"2023-05-08T08:36:11+00:00\",\"index\":\"\",\"fulltext\":\"\"},{\"type\":\"editorInvited\",\"content\":\"Hormones\",\"date\":\"2023-05-02T13:19:07+00:00\",\"index\":\"\",\"fulltext\":\"\"},{\"type\":\"editorAssigned\",\"content\":\"\",\"date\":\"2023-05-01T23:55:41+00:00\",\"index\":\"\",\"fulltext\":\"\"},{\"type\":\"submitted\",\"content\":\"Hormones\",\"date\":\"2023-05-01T05:47:47+00:00\",\"index\":\"\",\"fulltext\":\"\"}],\"status\":\"published\",\"journal\":{\"display\":true,\"email\":\"info@researchsquare.com\",\"identity\":\"hormones\",\"isNatureJournal\":false,\"hasQc\":true,\"allowDirectSubmit\":false,\"externalIdentity\":\"HORM\",\"sideBox\":\"Learn more about [Hormones](https://www.springer.com/journal/42000)\",\"snPcode\":\"42000\",\"submissionUrl\":\"https://www.editorialmanager.com/horm/default2.aspx\",\"title\":\"Hormones\",\"twitterHandle\":\"\",\"acdcEnabled\":true,\"dfaEnabled\":true,\"editorialSystem\":\"em\",\"reportingPortfolio\":\"Springer Hybrid\",\"inReviewEnabled\":true,\"inReviewRevisionsEnabled\":false}}],\"origin\":\"\",\"ownerIdentity\":\"24f7c8da-0cfd-468d-b355-aad45a61ec1e\",\"owner\":[],\"postedDate\":\"May 10th, 2023\",\"published\":true,\"recentEditorialEvents\":[],\"rejectedJournal\":[],\"revision\":\"\",\"amendment\":\"\",\"status\":\"published-in-journal\",\"subjectAreas\":[],\"tags\":[],\"updatedAt\":\"2023-12-18T15:07:45+00:00\",\"versionOfRecord\":{\"articleIdentity\":\"rs-2876461\",\"link\":\"https://doi.org/10.1007/s42000-023-00516-9\",\"journal\":{\"identity\":\"hormones\",\"isVorOnly\":false,\"title\":\"Hormones\"},\"publishedOn\":\"2023-12-16 15:01:48\",\"publishedOnDateReadable\":\"December 16th, 2023\"},\"versionCreatedAt\":\"2023-05-10 17:48:17\",\"video\":\"\",\"vorDoi\":\"10.1007/s42000-023-00516-9\",\"vorDoiUrl\":\"https://doi.org/10.1007/s42000-023-00516-9\",\"workflowStages\":[]},\"version\":\"v1\",\"identity\":\"rs-2876461\",\"journalConfig\":\"researchsquare\"},\"__N_SSP\":true},\"page\":\"/article/[identity]/[[...version]]\",\"query\":{\"redirect\":\"/article/rs-2876461\",\"identity\":\"rs-2876461\",\"version\":[\"v1\"]},\"buildId\":\"_2-kVJe1T_tPrBINL-cwx\",\"isFallback\":false,\"isExperimentalCompile\":false,\"dynamicIds\":[84888],\"gssp\":true,\"scriptLoader\":[]}","source_license":"CC-BY-4.0","license_restricted":false}