 Hello everyone, welcome to the Indian Radiologist. Over the next few minutes, I will be talking about MRI imaging in endometriosis. This is the first case showing acystic lesion in left adnexa appearing hypointense on T2 on left side and hyperintense on T1 image on right side. This particular layered hypointense appearance on T2 image is called as the shading sign and is very typical of endometrioma. The left adnexal acystic lesion appears hyperintense on first even fat sat image with small dependent T2 hypointense areas of blooming on second and third GR images, suggesting foci of hemorrhage and confirming the diagnosis of endometrioma. Now let us take a look at the second case. These images show acystic lesions showing a layered hypointense appearance on T2, the so called shading sign in bilateral adnexate consistent with endometriomas, ovarian follicles can be seen as the periphery. This particular appearance of hemorrhage containing acystic lesions in close contact with each other within the pouch of Douglas is called as the kissing ovaries sign and is often seen in endometriosis. The same acystic lesions appear hyperintense on T1 weighted fat sat images. Acystic lesions appear hypointense on star images on right side, hence for a lesion which appears hyperintense on T1, differentiation between an endometriotic cyst and dermoid should be done only with a T1 fat sat image to exclude the presence of fat. In addition to the above findings, sagittal T2 images show suspicious speculations along the posterior surface of uterus causing tethering of the adjoining rectum and raising a suspicion of deep pelvic endometriosis. Also the uterus appears bulky with thickening of the posterior junction zone suggestive of adenomyosis. Now coming to the third case, in addition to the hemorrhage containing bilateral adnexal cystic lesions, the T2 axial images show irregular speculated T2 hypointense soft tissue in the pouch of Douglas causing tethering of the rectum. Sagittal T2 weighted images confirm the findings and in addition the uterus appears bulky with thickening of the posterior junction zone and raising the possibility of adenomyosis. Post contrast sagittal T1 fat sat images show irregular heterogeneous enhancement of the T2 hypointense soft tissue in the pouch of Douglas. Sagittal GRE images show T2 hypointense areas of looming within the hypointense speculated soft tissue and pelvis suggesting fochoir hemorrhage. These findings suggest likelihood of deep pelvic endometriosis. Overall findings are suggestive of bilateral ovarian endometrium mass with deep pelvic endometriosis and uterine adenomyosis. Coming on to the next case, bilateral adnexal cystic lesions are seen showing T2 shading sign with adjacent ovarian follicles. The right adnexal lesion appears hyperintense and the left adnexal lesion appears isointense on T1 fat sat images. In addition, there are elongated irregular cystic lesions with incomplete septations in bilateral adnexate adjacent to the above mentioned cystic lesions consistent with hematosolpings. The hematosolpings on left side appears hyperintense and the one on right side appears isointense on T1 weighted fat sat images. These varied appearances on T2 and T1 images are due to hemorrhage in different stages. Apart from bilateral ovarian endometrium mass and hematosolpings, there is a lobulated septated cystic lesion in right inguinal region which is the canal of NUK. T1 fat sat image shows a hyperintense focus within this lesion and GRE images show hyperintense areas of blooming consistent with foci of hemorrhage. This patient complained of swelling in the right inguinal region and pain during her periods. In view of bilateral ovarian endometrium mass, hematosolpings and the clinical history, this lesion in right inguinal region is consistent with a canal of NUK endometrioma. Let's take a look at the images of the next case. There is a fairly well defined isointense lesion involving the anterior wall of rectum with irregular speculated soft tissue in the pouch of Douglas. As seen in a couple of previous cases, this lesion shows hyperintense areas on T1 fat sat image consistent with hemorrhage. The patient complained of irregular cycles, pain in rectal region during her periods and constipation. The appearance of this lesion remained unchanged as compared with the previous MRIs and was proven to be an endometriotic deposit rather than C-erectum. Coming to the last case, this patient had a history of previous caesarean section and cyclical pain along the anterior abdominal wall. There is an irregularly marginated heterogeneous lesion in right rectus muscle along the site of previous caesarean scar containing T2 hyperintense foci suggesting foci of hemorrhage. These imaging findings with the clinical history are suggestive of scar endometriosis. It is thought to be caused by implantation of endometrial stem cells at the surgical site at the time of surgery. To summarize the MRI imaging findings in endometriosis, endometriomas can be seen as multiple adnexal cysts with T1 hyperintensity or one or more cysts with high T1 and shading on T2. Pelvic endometriotic deposits can be seen as hemorrhagic powder burn appearance with multiple lesions appearing bright on T1 fat saturated sequences. Small solid depletions may be hyperintense on T1 and hyperintense on T2. Adhesions and fibrosis can be seen as isointense to pelvic muscles on both T1 and T2 weighted sequences. Speculated low signal density stranding that obscures organ interfaces causing distortion of the normal anatomy which can be seen as posterior displacement of the uterus, casing ovaries sign and angulation of bobble loops. Elevation of the posterior vaginal phonics can be seen with loss of hyperintense signal of the posterior vaginal wall on T2. Thickening, nodules and masses can also be potentially seen. Loculated fluid collections can be seen, hematosalpings can be fairly diagnostic of endometriosis. Uterosecral ligaments are one of the common sites in deep pelvic endometriosis. Normal uterosecral ligaments are smooth and regular in contour. In endometriosis these can be irregular with asymmetric nodularity and thickening. Taurus utrinus which is the site of attachment of uterosecral ligaments on the posterior aspect of uterus is commonly involved in deep pelvic endometriosis. When pouch of Douglas is involved, it can be partially or completely obliterated, suspended or lateralized fluid collections can be seen. In urinary tract involvement, localized or diffuse bladder wall thickening can be seen with signal intensity abnormality. Nodules or masses are usually located at the level of vasicouterine pouch. Involvement of bladder mucosa is rare. Rarely, chest can be involved in endometriosis wherein cataminyl hemothorax, hemothorax or lung nodules can be seen.