The Influence of Bowel Preparation on ADC Measurements: Comparison between Conventional DWI and DWIBS Sequences

Background and objectives: The aim of the study was to assess whether there were di ff erences between apparent di ff usion coe ffi cient (ADC) values of di ff usion-weighted imaging (DWI) and di ff usion-weighted imaging with background body signal suppression (DWIBS) sequences in non-prepared and prepared bowels before and after preparation with an enteric hyperosmolar agent, to assess whether ADC measurements have the potential to avoid bowel preparation and whether ADC-DWIBS has advantages over ADC-DWI. Materials and Methods: 106 adult patients without evidence of inflammatory bowel disease (IBD) underwent magnetic resonance (MR) enterography before and after bowel preparation. ADC-DWI and ADC-DWIBS values were measured in the intestinal and colonic walls demonstrating high signal intensity (SI) at DWI tracking images of b = 800 s /mm2 before and after preparation. Results: There were significant di ff erence (p < 0.0001) in both ADC-DWI and ADC-DWIBS results between non-prepared and prepared jejunum for DWI being 1.09 x 10 3 mm2 /s and 1.76 x 10 3 mm2 /s, respectively, and for DWIBS being 0.91 x 10 3 mm2 /s and 1.75 x 10 3 mm2 /s, respectively. Both ADC-DWI and DWIBS also showed significant di ff erence between non-prepared and prepared colon (p < 0.0001), with DWI values 1.41 x 10 3 mm2 /s and 2.13 x 10 3 mm2 /s, and DWIBS-1.01 x 10 3mm2 /s and 2.04 x 10 3mm2 /s, respectively. Nosignificant di ff erence between ADC-DWI and ADC-DWIBS was found in prepared jejunum (p = 0.84) and prepared colon (p = 0.58), whereas a significant di ff erence was found in non-prepared jejunum and non-prepared colon (p = 0.0001 in both samples). Conclusions: ADC between DWI and DWIBS does not di ff er in prepared bowel walls but demonstrates a di ff erence in non-prepared bowel. ADC in non-prepared bowel is lower than in prepared bowel and possible overlap with the ADC range of IBD is possible in non-prepared bowel. ADC-DWIBS has no advantage over ADC-DWI in regard to IBD assessment.