Diagnostic value of diffusion-weighted imaging (DWI) for the assessment of the small bowel in patients with inflammatory bowel disease

Aim To evaluate diffusion-weighted imaging (DWI) compared to standard magnetic resonance imaging (sMRI) in the assessment of inflammatory lesions of the small bowel. Materials and methods Two readers retrospectively analysed MRI images of the small bowel including DWI followed by capsule endoscopy (CE) and ileocolonoscopy (ICS) in 30 consecutive patients with a suspected or established diagnosis of inflammatory bowel disease. Small bowel CE and the combination of CE + ICS were used as the standards of reference. Inflammatory lesions of the small bowel detected at endoscopy were compared with the findings of (1) sMRI alone (MRI without DWI), (2) DWI alone, and (3) sMRI in combination with DWI (sMRI + DWI). The sensitivity, specificity, and accuracy were calculated for all three readouts. The results of the three readouts were compared with each other. Results Using CE + ICS as the standard of reference, the mean sensitivity and specificity for the detection of inflammatory lesions of the small bowel at sMRI were 55.2% and 99.5%, at DWI 60% and 99%, and at sMRI + DWI 70% and 99%. Interobserver agreement between the two readers was very good (k=0.87–0.95). Two lesions in different patients were only detected at DWI. Conclusion DWI of the small bowel not only allowed for the detection of inflammatory lesions with high accuracy, but also enabled the identification of additional lesions that were not found using sMRI alone.