TECHNIQUES FOR MEASURING RENAL TRANSIT-TIME

A variety of techniques have been used for quantitative estimation of renal transit time. We compared different indices of transit time in a group of 30 patients having baseline and ACE inhibitor technetium-99m mercaptoacetyltriglycine (MAG(3)) renography prior to arteriography: peak time, mean transit time, and the ratio of background-subtracted c ounts at 20 min to those at 3 min, Each index was calculated from whol e-kidney ROI, cortical ROI, and cortical factor (by factor analysis). The strongest correlations between angiographic percent of stenosis an d transit time index were observed for the peak time (Spearman rho=0.3 69, n=53, P <0.005) and for the R20/3 (again rho=0.369, n=53, P <0.005 ) using the whole-kidney ROI and using only the baseline data without captopril. (Spearman's rho is simply the correlation coefficient calcu lated from rank in list, which allows for nonlinear correlation.) Thus simple indices of transit time (whole-kidney peak time and R20/3) cor related as well with The observed pathology as did more complicated me thods that required deconvolution, factor analysis, or selection of a cortical ROI.