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* = Presenting author

P244 Diffusion-weighted MRI enables to accurately grade inflammatory activity in patients of ileocolonic Crohn's disease: results from an observational study

Mao R.1, Li X.2, Li Z.2, Chen M.*1

1The first affiliated hospital of Sun Yat-Sen University, Department of Gastroenterology, Guangzhou, China 2The first affiliated hospital of Sun Yat-Sen University, Department of Radiology, Guangzhou, China

Background

Diffusion-weighted imaging (DWI) is a novel technique to evaluate bowel inflammation in Crohn's disease (CD). It remains unclear whether DWI could differentiate grades of inflammation activity and add to the accuracy of conventional magnetic resonance enterography (MRE) in defining disease activity. We aimed to assess the accuracy of DWI for evaluating ileocolonic CD inflammation compared with conventional MRE, using ileocolonoscopy as reference standard.

Methods

This was an observational study of CD patients who underwent both ileocolonoscopy and MRE with DWI. The conventional MRE and DWI findings of the ileocolon were scored from 0 to 3. The respective segment endoscopic disease activity was scored by simplified endoscopic score for Crohn's disease (SES-CD) and was graded as inactive (0–2), mild (3–6) or moderate-severe (≥7).

Results

185 bowel segments from 43 consecutive CD patients were evaluated and included inactive (n=86), mild (n=72), and moderate-severe (n=27) ileo-colonic segments. The area under the receiver operating characteristics curve (AUC) of 0.973 for apparent diffusion coefficient (ADC) to differentiate active from inactive CD was significantly higher than those of conventional MRE parameters (AUC between0.840–0.940). Higher accuracy of ADC (AUC=0.919) for differentiating inactive-mild from moderate-severe CD was also shown compared with that of conventional MRE parameters (AUC between0.868–0.915). ADC values demonstrated strongest correlation with SES-CD (r=−0.880) comparing to DWI SI and conventional MRE parameters (r between 0.787- 0.867).

Conclusion

DWI enables to accurately grade inflammatory activity in patients of ileocolonic CD and may be better suited than conventional MRE for monitoring the activity of CD.