{"paper_id":"a5a76c0f-1999-4597-87d2-cdae46c38a72","body_text":"R E S E A R C H Open Access\nCan diffusion and T2 star-weighted\nmagnetic resonance imaging aid in the\ndiagnosis of ectopic endometrium?\nMariam Raafat 1,2* , Soha H. Talaat 2, Salma M. Abdelghaffar 2 and Engy A. Ali 2\nAbstract\nBackground: Endometriosis is a common gynecologic disorder characterized by the implantation of the\nendometrial tissue ectopically outside the endometrial cavity. It affects about 10% of females at the childbearing\nperiod and is estimated to be present up to 20 –50% in women complaining of infertility. While laparoscopy is\nconsidered the mainstay for diagnosis, magnetic resonance imaging (MRI) is recognized as a useful tool for\ndefinitive diagnosis, pre-surgical planning, and determining whether the patient will require multi-specialty\ninvolvement. The aim of this study is to evaluate the performance of MRI with the addition of diffusion-weighted\nimaging (DWI) and T2 star (T2*) to conventional MRI, for the accurate assessment of ectopic endometrium.\nResults: Endometriotic lesions that showed diffusion restriction on DWI were 80.7%, and 96.1% of the\nendometriotic lesions had signal voids on the T2*W sequence, whereas only 65.4% of the lesions had typical signal\nintensities on T1WI and T2WI. Diagnostic performance of the MRI examination was improved by the use of the\ndiffusion sequence and better improved by the T2* sequence, compared to the conventional MR protocol\nsensitivity (SE) = 96.12% and specificity (SP) = 85.7% in T2*-weighted images, SE = 80.7% and SP = 71.4% in DWI,\nand SE = 65.4% and SP = 71.4% in conventional MRI. P value for conventional MRI was 0.1, which is of no statistical\nsignificance ( p < 0.05). P value for DWI was 0.016, which is statistically significant ( p < 0.05). P value for T2*WI was\n0.001, which is more statistically significant ( p < 0.05) and could be adequately correlated with laparoscopy.\nConclusion: DWI and T2* significantly increase MRI diagnostic accuracy by allowing the detection of the\nhemorrhagic character of the endometriotic lesions. Studies with a large sample size are needed to confirm that\nthey can replace invasive laparoscopy for the diagnosis of endometriosis.\nKeywords: Endometriosis, MRI, DWI, T2*WI\nBackground\nEndometriosis is a common gynecologic disorder\ncharacterized by the implantation of endometrial tissue\nectopically outside the endometrial cavity. The prevalence\nis approximately 10% of females at the childbearing period\nand is estimated to be present up to 20 –50% in women\ncomplaining of infertility [ 1]. It is known to cause various\nsymptoms, including chronic pelvic pain, dysmenorrhea,\ndyspareunia, and infertility [ 2]. Ultrasound (US) is usually\nthe first modality used in the diagnosis of endometriotic\nlesions; however, MRI has many advantages to US with\nmore reproducible image acquisition over a larger field of\nview allowing the detection of disease outside the pelvis.\nInformation collected from multiple sequences leads to\nbetter characterization of ovarian lesions [3].\nWhile laparoscopy is considered the mainstay for diag-\nnosis, MRI is recognized as a useful tool for definitive\ndiagnosis, pre-surgical planning, and determining whether\nthe patient will require multi-specialty involvement [4].\n© The Author(s). 2021 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License,\nwhich permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give\nappropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if\nchanges were made. The images or other third party material in this article are included in the article's Creative Commons\nlicence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons\nlicence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain\npermission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.\n* Correspondence: mariam_raafat@yahoo.com\n1Diagnostic and Intervention Radiology Department, Cairo University\nHospitals, Kasr Al-Ainy, El-Manial, Cairo 11956, Egypt\n2Diagnostic and Interventional Radiology Department (Women ’s Imaging\nUnit), Kasr ElAiny Hospital, Cairo University, Giza, Egypt\nEgyptian Journal of Radiology\nand Nuclear Medicine\nRaafat et al. Egyptian Journal of Radiology and Nuclear Medicine          (2021) 52:137 \nhttps://doi.org/10.1186/s43055-021-00513-1\n\nThough there is a wide range of imaging appearances\nof endometriosis, yet their hemorrhagic elements are\nits main characterizing imaging feature aiding in its\ndiagnosis [ 5].\nEndometriomas contain various stages of hemorrhage,\nthus produces a wide range of signal behaviors; the\nshading sign can vary from faint shading to complete\nsignal voiding. Therefore, it is assumed that the degree\nor volume of shading would differ between endometrio-\nmas and hemorrhagic cysts [ 6].\nDiffusion-weighted imaging (DWI) contributes struc-\ntural and functional information about the biological\ntissues, without using ionizing radiation or intravenous\ncontrast. Endometriotic implants may show diffusion\nrestriction [ 7]. A role for DWI is distinguished in the\ndifferentiation between endometriomas and hemorrhagic\ncysts with significantly lower apparent diffusion coeffi-\ncient (ADC) values in endometriomas when compared\nto hemorrhagic ovarian cysts at all b values [ 8].\nA characteristic feature of endometriosis is cyclic\nhemorrhage caused by ectopic endometrium resulting in\ndeposition of concentrated hemosiderin-laden within the\ncyst. Identification of this hemosiderin deposit by MRI\nhelps in the diagnosis of endometriomas [ 9].\nT2*-weighted images show magnetic susceptibility effects\nas signal voids. It is sensitive t o hemosiderin; consequently,\nit aids in the detection of old hemorrhagic content in endo-\nmetriotic implants and endometriomas [2].\nThe purpose of this study is to evaluate the perform-\nance of MRI with the addition of diffusion-weighted im-\naging and T2* to conventional MRI, for the accurate\nassessment of endometriosis.\nMethods\nPatients\nThis cross-sectional prospective study was done during\nthe diagnostic step or the pre-operative assessment of\nendometriosis, between August 2019 and August 2020.\nThough MRI was performed on 120 patients, yet our\nquantitative studies included only the surgically/laparo-\nscopically confirmed lesions which were 60 patients with\n66 lesions. Their ages ranged from 17 to 44 years. The\nmean patient age was 31.4 ± 8.13 years.\nInclusion criteria\nThe following are the inclusion criteria:\n– Cystic adnexal/pelvic masses with typical\nendometriosis signal in ultrasound\n– Infertile females seeking fertility, who were referred\nfrom the obstetrics and gynecology department with\nultrasound showing suspicion of endometriosis\n– Women complaining of chronic pelvic pain,\nespecially if it was cyclic\nExclusion criteria\nThe following are the exclusion criteria:\n– Patients with complex ovarian masses, those\ncontaining solid lesions.\n– We also excluded patients who have a\ncontraindication to MRI examination, such as those\nhaving aneurysmal clips and pacemakers.\nMagnetic resonance imaging\nThe MRI was conducted with a 1.5-T magnet device\n(Gyroscan INTERA and ACHIEVA, Philips Medical\nSystems, the Netherland), using a pelvic phased-array\ncoil with eight channels.\nMRI device: the protocol included T1W, with and\nwithout fat saturation sequences; T2W; DWI; and T2*-\nweighted imaging. MRI results were correlated with\nhistopathological findings in patients who underwent\nlaparoscopy, laparotomy, or open surgical treatment.\nImaging was performed regardless of the stage of the\nmenstrual cycle.\nPatient preparation\nThe following are the patient preparations:\n/C15Fasting (4 –6 h) before the examination.\n/C15Bowel enema administered approximately 2 –3h\nbefore the examination, with 2 doses of an oral\nlaxative (5 mg bisacodyl per dose) the day before\nimaging.\n/C15Follow a low-residue diet on the day before and the\nday of the examination.\n/C15Anti-peristaltic agent is administered intravenously\nbefore the examination.\n/C15Ten milligrams of butylescopolamine (Buscopan;\nBoehringer Ingelheim, Ingelheim, Germany).\n/C15Moderate bladder filling, by not urinating 1 h before\nthe study.\n/C15An overfilled bladder may produce movement\nartifacts and alter the anatomy of the pelvis.\nPatient position\nPatient was imaged in the supine position.\nThe protocol used in our study is summarized in\nTable 1.\nImage analysis\nMR image interpretation was performed by 2 expert ra-\ndiologists with more than 10 years of experience in MRI\nwho were blinded about each other ’s imaging findings,\nand they were not aware about the pathology.\nIn our MRI interpretation, following Foti et al. [ 2], the\ncriteria considered for the prediction of endometriosis\nwere as follows:\nRaafat et al. Egyptian Journal of Radiology and Nuclear Medicine          (2021) 52:137 Page 2 of 9\n\n(1) High signal on T1-weighted images with and with-\nout fat suppression\n(2) Intermediate to low T2WI signal with shading\n(3) Restriction at diffusion\n(4) Punctate or curvilinear signal voids at T2*WI.\nOur data analysis focused upon DWI SI and measured\nADC values, as well as T2* signal for the cystic adnexal\nmasses.\nDiffusion-weighted images\nDW images were observed for the presence of a persist-\nent high signal (restricted diffusion) with an increasing b\nvalue in correlation with the hemorrhagic components\nof the included lesions. Matched ADC maps were done\nusing a Phillips Advantage windows workstation with\nfunctional tool software. We measured the ADC values\nby manually applying region of interest (ROI) on the\nrestricted portions of the lesions.\nROI was specifically placed at areas of bright SI on\nDW images. For lesions with a hemorrhagic component,\na large ROI was applied to cover as much as possible of\nthe pathology, in case of lesions with multiple small\nscattered hemorrhages; multiple ROIs were applied to\nthe areas of concern, and an average was obtained.\nSurgical findings\nSurgical findings were considered as the gold standard.\nThe possible pathology of the endometriosis was sug-\ngested by conventional MR imaging, diffusion-weighted\nimaging, and T2*-weighted imaging and had been corre-\nlated with surgical pathology specimen in patients who\nhave undergone laparoscopy, laparotomy, or open surgi-\ncal treatment.\nStatistical analysis\nWe used software (SPSS for Windows, version 10.0.1,\n1999; SPSS, Chicago, Ill) for statistical analysis.\nQualitative variables are described as frequencies and\npercentages. To assess the diagnostic performance, the\nsensitivity, specificity, positive predictive value, and negative\npredictive values were estimated from the associated con-\ntingency table. Diagnostic performance values of MRI were\nonly evaluated for the patients who underwent laparoscopy,\nlaparotomy, or open surgery.\nMRI signal of endometriosis lesions in T1-weighted\nimages with and without fat suppression, T2-weighted\nimages, diffusion-weighted images, and in T2* sequence\nwere compared using percentages, by analyzing the\nendometriotic lesions found in operated patients.\nA P value less than 0.05 was considered statistically\nsignificant in all analyses.\nResults\nThough the study included about one hundred and\ntwenty cases, yet histopathologic examination was the\nonly confirmatory method for the lesions; thus, our\nquantitative studies included only the surgically/laparo-\nscopically confirmed lesions. MR image interpretation\nwas performed by 2 expert radiologists with more than\n10 years of experience. The inter-observer reliability\nbetween the two radiologists was calculated through the\nCohn Kappa test which was 0.97, indicating perfect\nagreement.\nSixty-six pathologically proven lesions in sixty patients\nwere identified as follows:\n– Thirty-four ovarian endometriomas\n– Eight abdominal wall cesarean scar endometriosis\n– Two bladder endometriosis\n– Eight adenomyosis\n– Fourteen non-endometriotic/hemorrhagic cysts\nSurgical/laparoscopic exploration and resection were\nperformed in 60 patients (30 did laparoscopy, 28 had\nopen surgeries, and 2 had undergone cystoscopy) with\n66 lesions, diagnosed as follows: 34 endometriomas in\n28 patients (6 bilateral (Fig. 1) and 22 unilateral), 8\nadenomyosis, 8 abdominal scar endometriosis, 2 bladder\nendometriosis, and 14 hemorrhagic cysts.\nMRI findings of the surgically proven endometrial\nlesions are shown in Table 2.\nTable 1 MRI protocol performed in the current study\nSequence TR (ms) TE (ms) FOV (mm) Matrix Slice thickness (mm) Flip angle\nT2 sagittal 3000 90 290 × 290 208 × 205 4 90\nT2 axial 3700 100 288 × 350 292 × 180 5 90\nT1 axial 500 10 260 × 216 263 × 171 5 90\nT1 FS axial 530 8 240 × 240 240 × 190 5 90\nT2 coronal 3000 90 300 × 300 272 × 200 4.5 90\nDWI (b0, 500, 1000) 2000 77 240 × 240 124 × 100 5 90\nT2* 500 4.6 240 × 240 256 × 256 4 20\nSlice gap is one mm and flip angle 90° in all sequences, except T2*, 20°\nAbbreviations: FOV field of view, FS fat suppression, DWI diffusion-weighted imaging\nRaafat et al. Egyptian Journal of Radiology and Nuclear Medicine          (2021) 52:137 Page 3 of 9\n\nThus, we noted that among the surgically confirmed\ncases of endometriosis, 32 out 52 cases showed typical\nappearance on conventional MRI, 42 out of 52 cases\nshowed diffusion restriction, and 50 out 52 cases showed\nsignal voids at T2 star-weighted MRI images. MRI ana-\nlysis with the aid of diffusion sequence showed excellent\noutcomes with the complete pathology specimen in 42\nlesions (26 endometriomas, 6 adenomyosis, 8 abdominal\nscar endometriosis, and 2 bladder wall endometriomas):\nSE = 80.7% ( n = 42/52) true positives and 10 false\nnegatives.\nThe mean apparent diffusion coefficient (ADC) value\nof the endometriotic lesions and adenomyosis was 1.03\nwith a minimum of 0.25, a maximum of 2.3, and 0.51\nstandard deviation. On the other hand, the mean ADC\nvalues of functional hemorrhagic cysts were significantly\nlower (0.71 ± 0.29 × 10 − 3m m2/s).\nWith the addition of T2*-weighted sequence, the results\nimproved where 50 out of 52 lesions were true positive\n(showing signal voids) (32 ovarian endometrioma (Fig. 2),\n8 adenomyosis (Fig. 3), 8 CS scar endometriosis (Fig. 4),\nand 2 bladder wall endometriosis (Fig. 5)): SE = 96.1%\n(n = 50/52) true positives and 2 false negatives.\nWe carried out a comparative study for the diagnostic\nperformance of the conventional MRI pelvic examin-\nation in addition to each of DWI and T2* in the assess-\nment of the pathologically diagnosed cases (Table 3).\nP value is calculated by the Fisher exact test. P value\nfor conventional MRI was 0.1, which is of no statistical\nsignificance ( p < 0.05). P value of DWI was 0.016, which\nis statistically significant ( p < 0.05). P value for T2*WI\nwas 0.001, which is more statistically significant and\ncould be adequately correlated with laparoscopy ( p <0 . 0 5 )\n(Fig. 6).\nDiscussion\nEndometriosis is a benign and chronic gynecologic\ndisorder, where there is ectopic implantation of endo-\nmetrial glands and stroma outside the uterine cavity.\nIt has been shown to cause various symptoms, includ-\ning chronic pelvic pain, dysmenorrhea, dyspareunia,\nand/or infertility [ 2].\nFig. 1 (a) TV-US showing bilateral ovarian cysts; the right is suggestive of endometrioma (ground glass), and the left is suggestive of hemorrhagic\ncyst (fishnet appearance). ( b) Axial MRI T1WI, showing bilateral ovarian cysts eliciting bright T1. Not suppressed with fat suppression ( c). Showing\nsubtle T2 shading ( d). With diffusion restriction ( e, f). Right curvilinear and left punctate signal voids in T2* ( g). Histopathological diagnosis:\nbilateral ovarian endometriosis\nTable 2 MRI findings of surgically proven cases\nSite High intensity on T1 weighted\nand low/shading on T2\nRestricted diffusion Signal void on T2* Surgical findings\nPresent Absent Present Absent Present Absent No.\nEndometriomas 16 (47.05%) 18 (52.95%) 26 (76.47%) 8 (23.53%) 32 (94.11%) 2 (5.89%) 34\nAbdominal scar 8 (100%) 0 (0%) 8 (100%) 0 (0%) 8 (100%) 0 (0%) 8\nBladder 2 (100%) 0 (0%) 2 (100%) 0 (0%) 2 (100%) 0 (0%) 2\nAdenomyosis 6 (75%) 2 (25%) 6 (75%) 2 (25%) 8 (100%) 0 (0%) 8\nNon-endometriomas 4 (28.57%) 10 (71.43%) 4 (28.57%) 10 (71.43%) 2 (14.28%) 12 (85.72%) 14\nRaafat et al. Egyptian Journal of Radiology and Nuclear Medicine          (2021) 52:137 Page 4 of 9\n\nEndometriomas can occur unilaterally or bilaterally,\nand approximately 28% of endometrioma patients have\nbilateral endometriomas [ 10].\nIn our study, bilaterality was observed in 35% of endo-\nmetriomas. However, as mentioned by Lee et al. [ 6],\nbilaterality cannot be used to reliably differentiate endo-\nmetriomas from other cystic lesions.\nThere is a range of imaging features in endometriosis,\nbut the hemorrhagic character of lesions markedly aids\nin their characterization [ 5].\nShading sign in T2-weighted MRI images is typical of\nendometriomas that helps differentiate it from other\nhemorrhagic ovarian lesions. Menstrual bleeding over\ntime and long term produce high iron concentration,\nprotein, and methemoglobin with consequent T2 short-\nening [ 11]. Lee et al. [ 6] reported that the shading sign\nhad a sensitivity and specificity of 90 –98% for the diag-\nnosis of endometriomas; however, his study included\nmore than 80% of the lesion endometriomas . Outwater\nand Dunton [ 12] conducted a study, where the sensitiv-\nity and specificity of T2 shading were only 68% and 83%,\nrespectively. In our study, conventional MRI with high\nT1-weighted images and shading sign in T2-weighted\nimages exhibited a sensitivity of 65.4% and a specificity\nof 71.4%. We believe that the shading is not a reliable\nMRI sign for differentiating endometriomas from\nhemorrhagic cysts.\nBlood or hemosiderin within endometriomas shortens\nT1, causing a consequent reduction in ADC values; there-\nfore, DWI may distinguish endometriomas from other\ncystic lesions [ 13]. In our study, 42 out of 52 pathologic-\nally proven endometriotic lesions and 4 non-endometrial\nhemorrhagic cysts showed restricted diffusion, with SE,\nSP, PPV, and NPP of 80.7%, 71.4%, 91.3%, and 50%,\nrespectively. Thus, DWI has shown an increase in sensitiv-\nity, PPV, and NPV yet similar specificity, when compared\nto conventional MRI. This is comparable to Abd El-\nDayem et al. ’s[ 14] study where 11 out of 14 cases were\nrestricted in DWI representing 78.57% sensitivity.\nHowever, due to the presence of overlap between the\nADC values of endometriomas and hemorrhagic cysts,\nthe diagnosis should be based upon the combination of\nclinical history and conventional MRI together with\nDWI findings and should not be based on DWI alone.\nIn 2002, it was suggested by Moteki et al. [ 15] that\nendometriomas had lower ADC values (0.91 ± 0.47 ×\n10−3 mm2/s) than other pelvic cysts (2.82 ± 0.80 × 10 −3\nmm2/s). Busard et al [ 16]. reported that ADC values of\nendometriomas are 1.10 ± 0.38 × 10 −3 mm2/s), and Lee\net al. [6]. calculated ADC values for endometriomas to\nFig. 2 (a) TV-US showing left ovarian chocolate cyst. It elicits heterogenous signal with peripheral high signal on T1 ( b), that is not suppressed on\nT1 fat suppression ( c), and no significant shading (not shown) nor significant diffusion restriction ( d, e) however punctate peripheral T2* signal\nvoid (f). Histopathological diagnosis: left ovarian endometriosis\nRaafat et al. Egyptian Journal of Radiology and Nuclear Medicine          (2021) 52:137 Page 5 of 9\n\nbe 1.06 ± 0.38 × 10 −3 mm2. These studies ’ results are\ncomparable to our study, which had mean ADC values\nfor endometriomas of 1.03 ± 0.51 × 10 −3 mm2/s.\nMethemoglobin and hemosiderin are especially well\nvisualized on T2*-weighted image that is a MR sequence\nthat is sensitive to blood by-products. The visualization of\nsignal voids is caused by the local heterogenicity of the\nmagnetic field, resulting from hemorrhagic products [5].\nTakeuchi et al. [ 17]r e p o r t e dt h a tT 2 *i m p r o v e d\nthe characterization of endometrioma by detecting\nFig. 4 (a) US of the anterior abdominal wall showing a well-defined infiltrative lesion implicating the right rectus muscle, infiltrating both the\nanterior and posterior rectus sheaths, and eliciting intermediate T1 SI ( b), with high T1FS ( c), intermediate T2 SI ( d). It shows focal areas of\ndiffusion restriction on DWIs ( e, f), and punctuate signal voids on T2*WI ( g)\nFig. 3 (a) Sagittal T2 MRI showing diffuse thickening and irregularity of the posterior junctional zone. The posterior fundal myometrium is heterogeneous\nshowing cystic changes bright in T1 and T2 (b, c). With diffusion restriction(d, e); T2* revealed signal void punctate foci (f), suggesting adenomyosis. N.B:\nleft adnexal cystic lesion showing facilitateddiffusion. Histopathological diagnosis: focal adenomyosis and left peritoneal inclusion cyst\nRaafat et al. Egyptian Journal of Radiology and Nuclear Medicine          (2021) 52:137 Page 6 of 9\n\nsignal void along the cyst wall as hemosiderin depos-\nition. Later in 2015, Takeuchi et al. [ 18]p r o v e dt h a t\nsignal voids as hemorrhagic components on T2*\nwere also observed in extra- ovarian endometriosis.\nMoreover, Pin et al. [ 5] suggested that T2* might be\nuseful and added as a sequence for treatment planning of\nendometriosis. Pin et al .[ 5] in their study stated that the\noverall diagnostic performances of MRI with T2* were im-\nproved regarding the evaluation of adnexal and deep infil-\ntrating endometriosis with an increase of the sensitivity\nfrom 88.2 to 94.1% and specificity from 68.8 to 73.3%.\nIn our study, with the addition of T2*WI, 50 out of 52\nendometriomas/adenomyosis showed signal voids. Thus,\nthe sensitivity improved from 65.4% by conventional im-\naging to 96.15% with the addition of T2*. Also, the spe-\ncificity improved from 71.4% by conventional imaging to\n85.7% with the addition of T2*.\nSo, in cases with doubtful ultrasound and conventional\nMRI findings in confirming the diagnosis of endometri-\nosis, DWI and T2* can represent an additional diagnos-\ntic tool in order to differentiate endometriomas from\nother cystic lesions.\nOur study had few limitations. Although the study was\noriginally done on 120 cases, yet only 66 lesions were in-\ncluded in the study as we considered the pathology is\nour gold standard; so, a larger sample size is needed.\nSusceptibility artifacts caused by intestinal gas may cam-\nouflage the detection of signal voids resulting from the\npresence of blood by-products within especially in cases\nof ultra-small and deep endometriotic foci. One of our\npatients was excluded from the study due to susceptibil-\nity artifacts caused by colonic overdistension, which lim-\nited the visibility of the pelvis. Two lesions were re-\nevaluated by two radiologists to sort out the discrepan-\ncies resulting from susceptibility artifacts.\nConclusion\nEndometriosis is the most common cause of chronic\npelvic pain in reproductive-age women. It affects ap-\nproximately 10% of women at the childbearing period.\nIt is found in 20 –50% of women with infertility and\nnearly 90% of women with chronic pelvic pain. It has a\nsignificant impact on the quality of life of women. In\naddition to the characteristic symptoms of dysmenorrhea,\nFig. 5 (a) Transabdominal US showing focal thickening of the dome of the urinary bladder, eliciting intermediate to high T1 ( b, c) and\nintermediate T2 SI ( d). It shows diffusion restriction on DWIs ( e, f) and signal void on T2* WI ( g)\nTable 3 Sensitivity, specificity, positive predictive value, negative predictive values of conventional MRI; DWI and signal void in T2*\nimages\nConventional MRI DWI with ADC maps Signal voids\nSensitivity (%) 65.4 80.7 96.15\nSpecificity (%) 71.4 71.4 85.7\nPPV (%) 89.47 91.3 96.2\nNPV (%) 35.7 50 85.7\nP value 0.106 0.016 0.001\nAccuracy (%) 66.7 78.8 93.9\nPPV positive predictive value, NPV negative predictive value\nRaafat et al. Egyptian Journal of Radiology and Nuclear Medicine          (2021) 52:137 Page 7 of 9\n\nnon-cyclic pelvic pain, infertility, and others, it causes psy-\nchological, marital, and social distress.\nOur study was performed during the diagnostic step\nor the pre-operative assessment of endometriosis. The\nMRI was conducted with a 1.5-T MRI device; the\nprotocol included T2W and T1W, with and without fat\nsaturation sequences complemented with a DWI, ADC\nmap, and a T2*WI, and the diagnostic performance\nvalues were evaluated. MRI results were correlated with\nsurgical findings in patients who underwent laparoscopy.\nEndometriotic lesions had restricted diffusion on DWI\nin 80.7%, and 96.1% of the endometriotic lesions had sig-\nnal losses on the T2*W sequence, whereas only 65.4% of\nthe lesions had typical signal intensities on T1WI and\nT2WI. Thus, the diagnostic performance of the MRI\nexamination was improved by the use of the diffusion\nsequence and better improved by the T2* sequence,\ncompared to the conventional.\nP value for conventional MRI was 0.1 which is not\nconsidered statistically significant when associated with\nlaparoscopy (p < 0.05). P value for DWI was 0.016,\nwhich is considered statistically significant when associ-\nated with laparoscopy (p < 0.05). P value for T2*WI was\n0.001, which is considered statistically significant when\nassociated with laparoscopy (p < 0.05).\nDiffusion-weighted imagining and T2* significantly in-\ncreases MRI diagnostic accuracy by allowing the detec-\ntion of the hemorrhagic character of endometriotic\nlesions. Studies with a large sample size are needed to\nconfirm that they can replace invasive laparoscopy for\nthe diagnosis of endometriosis.\nWe recommend the addition of diffusion-weighted im-\naging and T2*-weighted imaging to all cases of suspected\nendometriosis.\nAbbreviations\nMRI: Magnetic resonance imaging; T2*: T2 star; US: Ultrasound;\nDWI: Diffusion-weighted imaging; SE: Sensitivity; SP: Specificity; FOV: Field of\nview; FS: Fat suppression; ADC: Apparent diffusion coefficient; PPV: Positive\npredictive value; NPV: Negative predictive value; ROI: Region of interest\nAcknowledgements\nNo acknowledgments\nAuthors’ contributions\nMR contributed to the study conception and design, collection of patients ’\ndata, and writing and editing of the manuscript. STH contributed to the\nreferral and follow-up of the cases. SMA helped in the collection and inter-\npretation of the data. EAA helped in the study deign and statistical analysis.\nAll authors read and approved the final manuscript.\nFunding\nNo funding sources\nAvailability of data and materials\nAvailable with the corresponding author upon request\nDeclarations\nEthics approval and consent to participate\nWritten informed consent was signed by all patients before the examination.\nThe study was approved by the ethics committee of the Faculty of Medicine,\nCairo University. Reference number is not applicable.\nFig. 6 (a) Transabdominal US showing bulky uterus with sunray appearance. Diffuse adenomyosis, evident by the markedly enlarged uterus, with\ndiffuse marked thickening of the heterogeneously hypointense junctional zone showing scattered tiny cystic changes within ( b, c). There is no\nrestricted diffusion on DWI ( d, e). However, the is peripheral curvilinear signal voids on T2*WI ( f)\nRaafat et al. Egyptian Journal of Radiology and Nuclear Medicine          (2021) 52:137 Page 8 of 9\n\nConsent for publication\nAll patients included in this research are above 16 years and all gave written\ninformed consent to publish the data contained within this study.\nCompeting interests\nThe authors declare that they have no competing interests.\nReceived: 9 March 2021 Accepted: 13 May 2021\nReferences\n1. Priyanka J, Michelle S, Luciana PC, Myra F, Nicole H, Chenchan H, Aoife K,\nSherelle LN, Refky N, Liina P, Anuradha SB, Angela T, Wendy V, Myles TT\n(2020) Endometriosis MRI lexicon: consensus statement from the Society of\nAbdominal Radiology Endometriosis Disease-Focused Panel. Abdominal\nRadiol 45(6):1552–1568\n2. Foti PV, Farina R, Palmucci S, Vizzini IAA, Libertini N, Coronella M, Spadola S,\nCaltabiano R, Iraci M, Basile A, Milone P (2018) Endometriosis: clinical\nfeatures, MR imaging findings and pathologic correlation. 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Abdom Imaging 40(7):\n2512–2516. https://doi.org/10.1007/s00261-015-0378-z\nPublisher’sN o t e\nSpringer Nature remains neutral with regard to jurisdictional claims in\npublished maps and institutional affiliations.\nRaafat et al. Egyptian Journal of Radiology and Nuclear Medicine          (2021) 52:137 Page 9 of 9","source_license":"CC0","license_restricted":false}