Typically the lesions that can be detected with MRI are those that contain blood products 23. hemorrhagic powder burn lesions appear bright on T1 fat-saturated sequences small solid deep lesions may be hyperintense on T1 and hypointense on T2 adhesions and fibrosis isointense to pelvic muscle on both T1 and T2 weighted images spiculated low signal intensity stranding that obscures organ interfaces 1 distortion of normal anatomy posterior displacement of the uterus kissing ovaries sign: seen in the severe forms of the disease angulation of bowel loops elevation of the posterior vaginal fornix loculated fluid collections hydrosalpinx endometriomas <5 mm: early-stage disease; >15 mm: advanced disease shading sign 25: may be less likely to respond to medical treatment 28 low T1 and T2 due to tissue and hemosiderin-laden macrophages 1 diagnostic criteria: multiple cysts with T1 hyperintensity OR one or more cysts with high T1 and shading on T2 uterosacral involvement 13 normal uterosacral ligaments are smooth and of regular contour irregular margins asymmetry nodularity and thickening medially (>9 mm) 13 altered T2 signal: isointense (50%), hypointense (40%) or hyperintense (10%) compared to myometrium if bilateral uterosacral involvement with additional involvement, torus uterinus involvement results in an arciform abnormality vaginal involvement loss of hypointense signal of the posterior vaginal wall on T2 thickening, nodules and / or masses also potentially seen pouch of Douglas partial to complete obliteration suspended or lateralized fluid collections rectovaginal septum: nodules or masses that have passed through the lower border of the posterior lip of the cervix gastrointestinal tract MRI has a low sensitivity (33%) for detecting rectal lesions 13 due to artefacts related to rectal content; sensitivity may be increased with the use of water enema, endovaginal coils and phased array coils 20 rectal wall thickening anterior displacement of the rectum abnormal angulation loss of fat plane between uterus and bowel inflammatory response due to repeated hemorrhage can lead to adhesions, strictures and bowel obstructions urinary tract bladder localized or diffuse bladder wall thickening signal intensity abnormality nodules or masses usually located at the level of the vesicouterine pouch involvement of bladder mucosa is rare chest catamenial pneumothorax hemothorax lung nodules cutaneous tissues: nodules malignant transformation: solid enhancing components Limitations of MRI Despite all the advantages of MRI over all other imaging modalities, it nonetheless has a number of limitations, including: non-pigmented lesions will not be hyperintense on T1, and thus harder to detect small foci may have variable signal intensity may appear similar to normal endometrium: low T1, high T2 hypointense on all sequences hyperintense on all sequences 1 plaque-like implants are difficult to delineate 26 adhesions cannot be directly identified, usually relying on the distortion of normal anatomy to imply their existence 26 Treatment and prognosis Treatment of endometriosis can be expectant, medical or surgical and will depend if the main problem is pain and / or subfertility 39.