Improved computer-assisted nuclear imaging in renovascular hypertension

Computer-assisted dynamic renal studies using both the 90 second 99mTc-DTPA and the conventional 30 minute 131I-Hippuran methods were performed in nine patients with angiographically proven renal artery stenosis. Time activity curves for both studies were derived from regions of interest selected from the computer-acquired dynamic images. The following parameters were used to assess renal blood flow: differential maximum activity, minimum/maximum activity ratio, and peak width. The computer-assisted DTPA study accurately predicted (9/9) the stenotic side documented angiographically, whereas the conventional Hippuran scan was clearly predictive in only 57% (5/9). The best discriminatory factors for the 90 second 99mTc-DTPA scan, when compared to a normal template synthesized from curves obtained from normal subjects (20), were differential maximum activity and peak width. In conclusion, the computer-assisted 90 second 99mTc-DTPA renal blood flow scan was superior to the conventional 30 minute 131I-Hippuran scan in demonstrating unilateral renovascular disease. The DTPA study was highly predictive of the angiographic findings, and this noninvasive study may prove useful in the diagnosis and serial evaluation following surgery or angioplasty in patients having renal artery stenosis.