[Hydro-MRI in inflammatory bowel diseases: a comparison with colonoscopy and histology]

To compare hydro-MRI with colonoscopy and biopsy specimen regarding the assessment of inflammatory activity and the differentiation of inflammatory bowel diseases.

After an oral bowel opacification using 1000 ml of a 2.5% mannitol solution and a rectal bowel opacification using 250-500 ml of a 0.9% saline solution, axial and coronal breath-hold sequences +/- Gd-DTPA (HASTE-["half-Fourier acquisition single-shot turbo spin echo"] and dynamic FLASH-["fast low angle shot"]) were acquired in 27 patients with inflammatory bowel disease. The enhancement of the bowel wall as well as morphological MRI findings were correlated with colonoscopy and biopsy specimens. By means of the MRI findings, Crohn's disease (CD) and ulcerative colitis (UC) should be differentiated.

In CD, a significant correlation between the contrast enhancement of the inflamed bowel wall (delta SI) and the endoscopic/histopathologic indices could be established (r = 0.52; p = 0.02 and r = 0.72; p = 0.001). In UC, no correlations between delta SI and the endoscopic/histopathologic indices could be found. The correct diagnosis of CD and UC by MRI findings was possible in 22/27 patients (81%).

Hydro-MRI with dynamic studies is suitable for the assessment of disease activity in CD, but unreliable in UC. Hydro-MRI provides useful information for the differentiation of CD and UC.