Diffusion-weighted imaging (DWI) may be a diagnostically acceptable replacement for a gadolinium contrast-enhanced magnetic resonance imaging (MRI) examination of children with suspected or known inflammatory bowel disease. A comparative analysis of exams of 55 pediatric patients at the Hôpital de la Timone in Marseilles, France, reported in the September issue of Pediatric Radiology showed that DWI was superior to contrast-enhanced MRI.
DWI is used to image inflammatory bowel disease in adults, but research about its diagnostic performance for pediatric patients is limited. Radiologists conducted an analysis of 55 consecutive patients aged 5 to 18 who had undergone MR enterography and endoscopy examinations. The patient cohort included 25 with Crohn disease, 11 with ulcerative recto-colitis, and 2 with undetermined recto-colitis. A conclusive diagnosis could not be determined with one patient. Inflammatory bowel disease was ruled out for 16 patients.
Two radiologists independently reviewed the two sets of images, morphologic sequences in combination with DWI sequences without contrast enhancement, followed 15 days later by morphologic sequences with contrast-enhanced images without DWI sequences. They divided MRI scans into 11 segments, five four the small bowel, five for the colon, and one for the rectum. The quality of bowel distention and bowel wall thickness on the morphologic sequences, the presence of a bowel wall hyperintensity on either a contrast-enhanced T1-weighted fat-saturated sequence or a DWI sequence, and the suspicion of disease were evaluated. The quality of bowel distention and signal intensity of the bowel wall were assessed using a 3-point scale and bowel wall thickness using a 2-point scale. Each exam was categorized as normal, equivocal, or pathological. Complications were noted.
Lead author Farah Khachab, MD, a pediatric radiologist, and colleagues, studied the difference of distribution between the DWI sequences and contrast-enhanced MRI sequences. They evaluated the number of differences between the results of the two sequences by performing 100,000 simulations. They also evaluated diagnostic performance for each variable and compared MRI results with the final diagnostic workup of each patient.
The authors reported that the sensitivity of DWI and contrast-enhanced MRI was 100% and 85% respectively for patients with Crohn disease. Similarly, the sensitivity of DWI outperformed contrast-enhanced MRI for patients with ulcerative recto-colitis, at 75% and 33% respectively. When findings were compared with all clinical data, the sensitivity and specificity for DWI was 90% and 82% respectively compared to 67% and 71% for contrast-enhanced MRI.
“DWI was found to be superior to contrast-enhanced MRI when compared to endoscopy and to have a 96% accuracy when compared to contrast-enhanced MR for the small bowel not explored by endoscopy,” they wrote. “In our study, when our gold standard endoscopy was rated as doubtful, DWI was more commonly in accordance with the final diagnosis as compared to contrast-enhanced MRI.”
The authors recommended that their findings be confirmed in a prospective, randomized multi-center study.
Feasibility of DWI for imaging pediatric inflammatory bowel disease. Appl Radiol.