A single injection technique for subtraction of blood background in 131I-hippuran renograms.

A method of subtracting blood background during proberenography is presented which does not require a prior injection of RIHSA and which produces results approximately 11% higher than the RIHSA method. The new method treats the renogram up to two-and-a-half minutes as a combination of a fraction of the blood curve and a fraction of the integral of the blood curve. Analysis of the data, using either a computer or a programmed calculator, enables these two fractions to be calculated, hence producing the "background subtraction factor" and the "uptake constant".