Role of gadolinium-enhanced magnetic resonance imaging in retroperitoneal fibrosis.

PURPOSE: To determine if the gadolinium-enhancement characteristics of magnetic resonance images (MRI) differ for acute and chronic benign retroperitoneal fibrosis (RPF).

METHOD: Seven male subjects, 3 with newly diagnosed nontreated RPF (acute group) and 4 with long-standing stable RPF (chronic group) who had been treated with steroids, ureteric stents or both, underwent MRI examinations with gadolinium enhancement. Patients in the acute group were examined again after treatment. Mean dynamic gadolinium-enhancement ratios (both dynamic and delayed) were calculated for each group.

RESULTS: The initial mean dynamic enhancement ratio for the acute group (mean 1.86, range 1.80-1.95) was significantly different (p = 0.005) from that of the chronic group (mean 1.37, range 1.26-1.61). The mean dynamic enhancement ratio for the acute group after treatment (4-8 months duration) was 1.40 (range 1.26-1.51). The mean delayed enhancement ratio (RPF/psoas muscle signal intensity) for the acute group was 1.41 (range 1.38-1.43, data from 2 patients) and for the chronic group was 1.29 (range 1.13-1.44).

CONCLUSION: Dynamic gadolinium enhancement was useful in differentiating newly diagnosed RPF from treated chronic disease and may have a role in assessing disease activity, monitoring response to treatment and detecting relapse.