Selection of renal background for quantitative 131I-hippurate relative renal function studies

In a series of 100 patients with a full range of normal to poor renal function it was found, using 99mTC--albumin, that the zone between the superior poles of the kidneys best approximates the vascular pool in the renal areas. It is therefore possible to perform sufficiently accurate background-corrected relative renal function studies with 131I-hippurate alone. It is most valid in monitoring renal function in follow-up examinations. Both the accumulated 1- to 2-min count and 0- to 3-min count of the estimated net 131I-hippurate renogram were compared to a standard 99mTc-albumin corrected 131I-hippurate renogram for relative renal function measurements and they correlated very well (r = 0.91). The integrated 0- to 3-min count is preferred to the integrated 1- to 2-min count as the former yields better counting statistics, particularly in renal failure.