RENAL VASCULAR TRANSIT-TIME AND TUBULAR TRANSIT-TIME DISPERSION FOR TC-99(M)-MAG3

Renal transit time usually refers to tubular transit time, as introduc ed by Taplin, but other measures oi renal transit have been proposed. Here we examine the vascular transit time (VIT; following Rutlandi and the standard deviation oi tubular transit time (SDTT, following Britt on) in a group of 30 patients having baseline and ACE-inhibitor Tc-99( m)-MAG3 renography prior to arteriography. A same-day low-dose/high-do se protocol was used for renography; only the post-captopril dose was high enough to measure VTT. Pre-captoyril, the Spearman rank correlati on coefficient for SDTT was rho = 0.52 (n = 53 kidneys; P< 0.0002); po st-captopril, rho = 0.54 (n = 49 kidneys; P < 0.0002), For VTT, the po st-captopril value was rho = 0.24 (n = 30 kidneys; N.S.). For comparis on, the same statistics were calculated fur Taplin's original measure of transit time: the time from injection to maximum count rate (peak t ime). Precaptopril, for peak time, rho was 0.47 (n = 53 kidneys; P < 0 .001); post-captopril, rho was 0.39 (n = 50 kidneys, P < 0.01). These findings confirm the diagnostic value of SDTT but not of VTT. SDTT cor related better than peak time with the arteriographic findings.