A. Gezici et al., Quantitative residual cortical activity measurement: Appropriate test for diagnosis of renal artery stenosis?, UROL INTERN, 62(1), 1999, pp. 1-7
Objectives: To evaluate the diagnostic validity of quantitative measurement
of residual cortical activity (RCA) in renal artery stenosis (RAS). Method
s: In 45 patients with a high clinical likelihood of renovascular hypertens
ion (RVH) and unimpaired renal function, dynamic imaging was performed afte
r an intravenous bolus injection of 148 MBq Tc-99m MAG3 for both baseline r
enoscintigraphy and captopril renography following oral application of 50 m
g captopril. RCA was measured according to the Sfa-kianakis method: RCA = c
ortical counts at 20 min/counts at peak x 100%. An increase in RCA of great
er than or equal to 5% from baseline was considered indicative of RAS. Afte
r renography, all patients underwent selective transfemoral angiography wit
h the digital subtraction technique. A luminal reduction of greater than or
equal to 50% was considered as proof of RAS. Results: The number of kidney
s that had a change of 15% in RCA values was 12 (27.2%) in normal kidneys,
7 (58.3%) in the patients with bilateral RAS, 14(82.3%) in the patients wit
h unilateral RAS, and 21 (72.4%) in overall kidneys with RAS. The positive
test ratio in pathologic groups was significantly higher than normal (p < 0
.05). The sensitivity and specificity of the RCA test were 72.4 and 72.7%,
respectively; the positive and negative predictive values were 63.6 and 80%
, respectively. Conclusion: Quantitative measurements of RCA can be used as
a diagnostic parameter of renal artery stenosis and may contribute of the
diagnostic accuracy of visual interpretation and other renographic diagnost
ic criteria.