PURPOSE: To evaluate magnetic resonance (MR) imaging morphologic- and signal 
intensity abnormalities of deep infiltrating endometriosis (DIE) of the bowel 
wall and to assess its value in predicting depth and extent of bowel wall 
infiltration.
MATERIALS AND METHODS: This single-center study was performed in a tertiary 
referral center for endometriosis. All patients (n = 28) who underwent segmental 
bowel resection (2004-2010) were retrospectively studied. MR images were 
analyzed by two experienced readers independently (number of lesions, location, 
size, signal intensity, and depth of bowel wall infiltration) and this was 
correlated with histopathology.
RESULTS: The sensitivity, specificity, positive and negative predictive values, 
and accuracy for diagnosis of endometriosis infiltrating the muscular layer of 
the bowel were 100%, 75%, 96%, 100%, and 96%, respectively. The inter-rater 
agreement was 0.84. "Fan shaped" configurations with hypointensity on T2- and 
T1-weighted imaging were characteristic for thickening of indigenous smooth 
muscle and smooth muscle hyperplasia at histopathology, as a consequence of 
infiltration by endometriosis. Thickening of the (sub)mucosa corresponded to 
edema with or without infiltration of endometriosis.
CONCLUSION: MR imaging at 1.5 Tesla is useful to predict muscular infiltration 
of the bowel in endometriosis, whereas it is of limited value in diagnosis of 
(sub)mucosal infiltration.