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 underwe nt 12 MR studies at 1.5 T, including T1-weighted gradient echo and fat -suppressed spin echo pre- and post-Gd-DTPA enhancement. Two radiologi sts 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, r enal abscesses were clearly depicted as heterogeneously low-signal-int ensity lesions. Four patients had solitary abscesses, and four had mul tiple abscesses. Prominent perinephric inflammatory stranding was obse rved 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 image s. Conclusion: Renal abscesses are clearly shown on gadolinium-enhance d MR images as low-signal-intensity lesions associated with prominent perinephric inflammatory strands. In this study, NCCT and ultrasound s tudies are poor at defining abscesses. Despite lesser contrast resolut ion of CECT versus MRI, the findings in cases of renal abscesses are s imilar. In patients with elevated serum creatinine, iodine contrast al lergy, or the need for serial exams, MRI may be the best imaging techn ique to evaluate renal abscesses.