Dynamic MRI of the small bowel: usefulness of quantitative contrast-enhancement parameters and time-signal intensity curves for differentiating between active and inactive Crohn's disease.

PURPOSE: To assess Crohn's disease (CD) activity through analysis of time-signal intensity curves and quantitative contrast-enhancement parameters on dynamic contrast-enhanced MRI. MATERIALS AND METHODS: 70 patients (male:female = 44:26, age 15-45 years, mean 27.8 years) with biopsy-proven clinically active or inactive CD, underwent dynamic contrast-enhanced MRI after oral administration of iso-osmotic solution. Time-signal intensity curves were classified according to their shape as type I (early upslope with late plateau) and type II (slow contrast material wash-in with late wash-out). Curve parameters such as maximum enhancement (ME), the ratio between late and ME (LE/ME), and UpSlope (US) were compared between patients with active and inactive CD (two-tailed Mann-Whitney test). Sensitivity, specificity, and cut-off for each parameter were calculated by means of receiver operating characteristic curve (ROC) analysis. RESULTS: 53/53 patients with active CD and 17/17 with inactive CD showed type I and type II curves, respectively. ME, LE/ME, and US were significantly higher in active than in inactive CD. ME, LE/ME, and US had sensitivity and specificity of 100%:100%:100% and 100%:83%:100% with cut-offs of 135.5:0.8909:2, respectively. CONCLUSIONS: Qualitative and quantitative analysis of time-signal intensity curves obtained with dynamic contrast-enhanced MRI allow reliable noninvasive differentiation between active and inactive CD.