P051 MR-enterography with diffusion weighted imaging and apparent diffusion coefficient map for assessing inflammatory bowel disease in children and adolescents

Abstract

BACKGROUND: Endoscopy has been considered as the gold standard for the assessment of gastrointestinal inflammation, however, it can only evaluate superficial mucosal layers. Crohn's disease could cause transmural inflammation in any part of the gastrointestinal tract. As a result, stenosis, perforation, and internal/external fistula formation can complicate with this inflammation, and assessing the inflammatory activity of the bowel wall, not limited to the superficial intestinal mucosa, would lead to the proper diagnosis as well as management to minimize complication in patients with inflammatory bowel disease (IBD). Small bowel inflammation can be evaluated by both magnetic resonance imaging (MRI) and computed tomography (CT), and they have shown similar accuracy and sensitivity for the detection of active inflammation. Recent studies have addressed the utility of Diffusion Weighted Imaging (DWI) and apparent diffusion coefficient (ADC) map in adult, while there have been few studies using these modalities in children and adolescents. The aim of this study was to explore the usefulness of ADC values in children with IBD. METHODS: Children and adolescents with IBD that required MR-enterography (free-breathing axial DWI with 2 b (0 and 800 s/mm2) was included) for the assessment of small intestinal lesion at a Japanese children's hospital were retrospectively reviewed. A total of 14 children and adolescents with IBD (12 CD and 2 UC), aged 5 to 23 years who had undergone MR-enterography from 2017 to 2018. Mean restricted ADC (r-ADC) value was obtained in a set of value (3 points of thickened bowel wall in all patients [n = 14]). Also, mean non-restricted ADC (nr-ADC) value was obtained from normal bowel wall as well as r-ADC described above. Fourteen age-matched control patients that had undergone MR-enterography were identified. In addition, mean ADC value of non-IBD patients (ni-ADC) was obtained from normal intestinal wall as a control group (e.g., neuroblastoma, n = 14). These values were compared using t-test. P < 0.05 were considered to indicate statistical significance. RESULTS: The r-ADC values were significantly lower than the nr-ADC values (1.118 ± 0.271 × 10−3 mm2/s vs 2.119 ± 0.252 × 10−3 mm2/s; P < 0.01). However, there was no significant difference between ni-ADC and nr-ADC (2.15 ± 0.217 × 10−3 mm2/s vs 2.119 ± 0.2519 × 10−3 mm2/s; P = 0.556). CONCLUSION(S): DWI and ADC map were useful in locating actively inflamed bowel segments. MR-enterography with DWI and ADC map appeared an excellent modality to assess intestinal inflammation that can be repeatedly used without radiation exposure, even in pediatric patients. Further studies to investigate for the threshold of ADC value that can be used for children with IBD should be considered.