Diagnostic value of renal scintigraphy with MAG 3 and DTPA in the diagnosis of renal artery stenosis

Angiography still remains the first line investigation to demonstrate a renal artery stenosis. We have evaluated the sensitivity and the specificity of renal scintigraphy in the diagnosis of renal artery stenosis using two technetium markers, MAG 3 and DTPA. Patients : 45 hypertensive (HT) patients (WHO criteria) referred for investigation of renovascular hypertension according to the criteria of the AHA Scientific Council and were found to have a unilateral renal artery stenosis of varying severity. Age was 61>± 13 years ; sex-ratio F/M 21/24 ; creatinine < 150 μmol/l. There were non insulin dependent diabetics, and none had been treated with ACE inhibitors or diuretics for 15 days. Bilateral arterial stenosis was excluded a posteriori. Methods : MAG3 and DTPA scintigraphy were performed one hour after a dose of 25 mg of captopril plus hydration with 500 ml of intravenous saline. Blood pressure was measured by dynamap every 15 min from minus one hour to the end of the study. The principle outcome measure was nephrogram phase and the secondary measure was the angiographic phase (two images per second). The two scintigraphy techniques were performed at a mean interval of 2.9 ± 2.1 days. Digitized angiography via the arterial route was performed using left anterior oblique and right anterior oblique images. Results : Tab. Conclusion : There was only one false positive scintigraphy result with a polar artery. In contrast 45% of unilateral stenoses were not diagnosed by scintigraphy. Both markers gave similar results even if subjectively the MAG3 images were of better quality. Analysis of the angiographic phase and of the size of the kidneys did not improve the diagnostic accuracy and could lead to false positive results.