Evaluation of Renal Blood Volume by PET

—The aorta-kidney equilibrium monitored with C¹⁵O—

Abstract

Twenty subjects inhaled C¹⁵O and its dynamics were monitored to determine when equi-librium between the aorta and kidney occurred. One minute after inhalation, the increase in radioactivity in the aorta paralleled that in the kidney, but thereafter, both declined slowly. The ratio of aorta/kidney radioactivity become constant 1 min after inhalation and remained unchanged for 4 min. Thus renal blood volume can be measured 1 min after inhalation of C¹⁵O its distribution in the aorta and kidney has attained equilibrium.