Purpose: To determine mural perfusion dynamics in Crohn disease by using dynamic contrast material-enhanced magnetic resonance (MR) imaging and to correlate these with histopathologic markers of inflammation and angiogenesis.
Materials and methods: Ethical permission was given by the University College London Hospital ethics committee, and informed consent was obtained from all participants. Eleven consecutive patients with Crohn disease (eight female patients, three men; mean age, 39.5 years; range, 16.4-66.6 years) undergoing elective small-bowel resection were recruited between July 2006 and December 2007. Harvey-Bradshaw index, C-reactive protein (CRP) level, and disease chronicity were recorded. Preoperatively, dynamic contrast-enhanced MR imaging was performed through the section of bowel destined for resection, and slope of enhancement, time to maximum enhancement, enhancement ratio, the volume transfer coefficient K(trans), and the extracellular volume fraction v(e) were calculated for the affected segment. Ex vivo surgical specimens were imaged to facilitate imaging-pathologic correlation. Histopathologic sampling of the specimen was performed through the imaged tissue, and microvascular density (MVD) was determined, together with acute and chronic inflammation scores. Correlations between clinical, MR imaging, and histopathologic data were made by using the Kendall rank correlation and linear regression.
Results: Disease chronicity was positively correlated with enhancement ratio (correlation coefficient, 0.82; P = .002). Slope of enhancement demonstrated a significant negative correlation with MVD (correlation coefficient, -0.86; P < .001). There was a negative correlation between CRP level and slope of enhancement (correlation coefficient, -0.77; P = .006). Neither acute nor chronic inflammation score correlated with any other parameter.
Conclusion: Certain MR imaging-derived mural hemodynamic parameters correlate with disease chronicity and angiogenesis in Crohn disease, but not with histologic and clinical markers of inflammation. Data support the working hypothesis that microvessel permeability increases with disease chronicity and that tissue MVD is actually inversely related to mural blood flow.