Evaluation of treatment response in active Crohn's disease by low-field magnetic resonance imaging

Background: To evaluate low-field magnetic resonance imaging (MRI) in detec ting therapeutic response in active Crohn's disease during treatment with s ystemic steroids. Methods: Eight patients with active Crohn's disease were examined before an d during treatment with systemic steroids (1 mg/kg/day) using low-field MRI (0.1 T) in transverse and coronal planes before and after an intravenously administered bolus of gadodiamide. Five healthy persons were once examined in the same way. MRI images were evaluated without knowledge of diagnosis, treatment, or findings of endoscopy, conventional radiography, and surgery . Proximal and mid small bowel, terminal ileum, right-sided colon, transver se colon, and left-sided colon were evaluated separately. Results: Statistically significant differences were shown for both signal i ntensity on T2- (SIT2) and increment in signal intensity on T1-weighted ima ges after contrast (%SIT1) when comparing diseased bowel segments with both nondiseased bowel segments (SIT2: p = 0.0001; %SIT2: p = 0.0009) and segme nts from the control group (SIT2: p < 0.00005; %SIT1: p < 0.00005). In 53 o f 56 bowel segments evaluated (95%), agreement was found between findings b y MRI, conventional radiography, endoscopy and/or surgery regarding disease extension. Extension was underestimated in two patients. All bowel segment s in the control subjects were evaluated to be normal on MRI. Significant c orrelation was found between both SIT1 (p < 0.0025) and %SIT1 (p < 0.025) v ersus endoscopic activity gradings. During treatment, significant decrement s of both SIT2 (p < 0.00005), %SIT1 (p = 0.002), and bowel wall thickness ( I, = 0.03) were found. Conclusions: Low-field MRI seems to be a promising noninvasive method in th e evaluation of response regarding both disease extension and activity in C rohn's disease during treatment with systemic steroids.