Renal abscesses: Appearance on gadolinium-enhanced magnetic resonance images

Purpose: To determine the appearance of renal abscesses on gadolinium-enhanced magnetic resonance (MR) images, we reviewed 12 MR studies of eight patients with renal abscesses. These findings were compared with findings on other imaging modalities. Methods: Eight patients underwent 12 MR studies at 1.5 T, including T1-weighted gradient echo and fat-suppressed spin echo pre- and post-Gd-DTPA enhancement. Two radiologists retrospectively reviewed the MR images and compared MR findings to the findings on contrast-enhanced computed tomography (CECT) in five patients, noncontrast computed tomography (NCCT) in two patients, and ultrasound in all patients. Results: On contrast-enhanced MR images, renal abscesses were clearly depicted as heterogeneously low-signal-intensity lesions. Four patients had solitary abscesses, and four had multiple abscesses. Prominent perinephric inflammatory stranding was observed in six patients and was best shown on gadolinium-enhanced T1 fat-suppressed images. CECT findings were comparable to contrast-enhanced MR images, although contrast resolution was less on CECT images in all cases. Renal abscesses were poorly shown on NCCT and ultrasound images. Conclusion: Renal abscesses are clearly shown on gadolinium-enhanced MR images as low-signal-intensity lesions associated with prominent perinephric inflammatory strands. In this study, NCCT and ultrasound studies are poor at defining abscesses. Despite lesser contrast resolution of CECT versus MRI, the findings in cases of renal abscesses are similar. In patients with elevated serum creatinine, iodine contrast allergy, or the need for serial exams, MRI may be the best imaging technique to evaluate renal abscesses.