MR renography with low-dose gadopentetate dimeglumine: Feasibility

PURPOSE: To develop a low-dose magnetic resonance (MR) renographic method p erformed with and without an angiotensin converting enzyme (ACE) inhibitor and in conjunction with gadolinium-enhanced MR angiography in patients with suspected renovascular disease. MATERIALS AND METHODS: Thirty-two patients underwent MR renography (turbo f ast low-angle shot sequence: repetition time, 5 msec; echo time, 2.3 msec; flip angle, 15 degrees; one coronal image acquired every 2 seconds for 4 mi nutes) following intravenous injection of 2 mL of gadopentetate dimeglumine , which was repeated following intravenous injection of an ACE inhibitor. C ontrast material-enhanced MR angiography was also performed. On the basis o f renographic findings, renal cortex and renal medulla enhancement curves a nd normalized enhancement ratios were analyzed. RESULTS: The cortex and medulla showed an early transient period of enhance ment within 20 seconds (vascular phase). During 1-2 minutes, a second, grad ual increase in medullary enhancement, reflecting transit of filtered contr ast material, was observed that was significantly greater in patients with a serum creatinine level less than 2 mg/dL (177 mu mol/L) than in those wit h a level of 2 mg/dL or greater (P <.01). After injection of the ACE inhibi tor, patients with elevated creatinine levels showed low renal medullary en hancement regardless of the presence of renal artery stenosis (RAS). Howeve r, in patients with creatinine less than 2 mg/dL, medullary enhancement rat ios after injection of the ACE inhibitor were consistently lower in patient s with RAS of 50% or greater than in those without stenosis (P =.02 to .08) . CONCLUSION: Low-dose MR renography can be performed in the clinical setting before and after injection of an ACE inhibitor, and its potential use for evaluating decreased renal function as a consequence of RAS is promising.