title: Evaluation of MR diffusion-weighted imaging in differentiating endometriosis infiltrating the bowel from colorectal carcinoma.
abstract: OBJECTIVE
  Endometriosis infiltrating the bowel may be difficult to differentiate from colorectal carcinoma in cases that present with non-specific clinical and imaging features. The aim of this study is to assess the value of MR diffusion-weighted imaging (DWI) in differentiating endometriosis infiltrating the bowel from colorectal carcinoma.
  
  
  METHODS
  In 66 patients, MR DWI was added to the standard imaging protocol in patients visiting our outdoor MR clinic for the analysis of suspected or known deep infiltrating endometriosis (DIE). In patients diagnosed with DIE infiltrating the bowel on MR imaging, high b-value diffusion-weighted images were qualitatively assessed by two readers in consensus and compared to high b-value diffusion weighted images in 15 patients evaluated for colorectal carcinoma. In addition, ADC values of lesions were calculated, using b-values of 50, 400 and 800 s/mm(2).
  
  
  RESULTS
  A total of 15 patients were diagnosed with DIE infiltrating the bowel on MR imaging. Endometriosis infiltrating the bowel showed low signal intensity on high b-value diffusion-weighted images in all patients, whereas colorectal carcinoma showed high signal intensity on high b-value diffusion-weighted images in all patients. Mean ADC value in endometriosis infiltrating the bowel (0.80 ± 0.06 × 10(-3)mm(2)/s) was significantly lower compared to mean ADC value in colorectal carcinoma (0.86 ± 0.06 × 10(-3 )mm(2)/s), but with considerable overlap between ADC values.
  
  
  CONCLUSIONS
  Only qualitative assessment of MR DWI may be valuable to facilitate differentiation between endometriosis infiltrating the bowel and colorectal carcinoma.
authors.affiliation: VU University Medical Center, Department of Radiology, De Boelelaan 1118, 1081 HZ Amsterdam, The Netherlands. m.busard@vumc.nl
authors.forename: M P H
authors.initials: MP
authors.lastname: Busard
authors.forename: I C
authors.initials: IC
authors.lastname: Pieters-van den Bos
authors.forename: V
authors.initials: V
authors.lastname: Mijatovic
authors.forename: C
authors.initials: C
authors.lastname: Van Kuijk
authors.forename: M C G
authors.initials: MC
authors.lastname: Bleeker
authors.forename: J H T M
authors.initials: JH
authors.lastname: van Waesberghe
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015179:Colorectal Neoplasms / Q000175:diagnosis* / Q000473:pathology; D003937:Diagnosis, Differential; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D004715:Endometriosis / Q000175:diagnosis* / Q000473:pathology; D005260:Female; D006801:Humans; D007422:Intestines / Q000473:pathology; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D018709:Statistics, Nonparametric