J Nucl Med. 2007; 48 (Supplement 2):293P
General Clinical Specialties: Renal/Electrolyte/Hypertension
Renal/Electrolyte/Hypertension Posters |
Incidence and significance of bilateral, symmetric changes in tubular function during aspirin-augmented renal scintigraphy
Dwight Achong1
1 Nuclear Medicine Service (115), James A. Haley Veterans' Hospital, Tampa, Florida
1305
Objectives: Aspirin (ASA) renography is an alternative study to identify significant renal artery stenosis (RAS) in patients allergic to captopril. The most common positive post-ASA finding is a unilateral degradation in tubular uptake and excretion. Symmetric, mirror image changes may pose a diagnostic dilemma: true-positive bilateral RAS or a false-positive result secondary to, e.g., ASA-induced nephrotoxicity. The incidence and significance of such symmetric post-ASA changes were retrospectively reviewed. Methods: 14 Tc-99m MAG3 renal scans were performed using a one-day protocol: 2 mCi MAG3 baseline 
20 mg/kg oral ASA (maximum 1625 mg) 8 mCi MAG3 60 min post-ASA. Each patient was hydrated with oral (10-15 ml/kg body weight) or I.V. (5-7 ml/kg) fluids. Blood pressure (BP) was monitored every 15 minutes following ASA. Post-ASA changes in tubular function were interpreted based on standard criteria. Results: In 7/14 (50%), there was no change in tubular function following ASA; the mean BUN/creatinine was 22/1.4 (range 11-37/0.6-1.9). In 2/14 (14%), there was a unilateral change; the mean BUN/creatinine was 17/1 (range 17-18/0.9-1.1). In 5/14 (36%), there were bilateral symmetric changes; the mean BUN/creatinine was 26/1.4 (range 19-54/1-1.8). No patient experienced a significant, > 10 mm Hg, drop in systolic or diastolic BP, nor was there any significant difference in baseline BUN/creatinine between any of the 3 groups. No patient with a normal study underwent angiography. 2/2 with unilateral change underwent angiography; both were positive for RAS. 3/5 with bilateral changes underwent angiography; all 3 were negative for bilateral RAS. Conclusions: There is a significant (36%) incidence of symmetric, mirror image changes in tubular function following ASA challenge, of unknown etiology and clinical significance. One possible etiology, direct nephrotoxicity secondary to the high ASA dose (unrelated to baseline renal function), could not be confirmed by this data. When such post-ASA changes are encountered, angiography may be required to exclude the unlikely etiology of bilateral RAS.
