Technetium-99m-Labelled RBC Erection Penogram to Differentiate Psychogenic from Vasculogenic Impotence

Abstract

The ^99mTc-labelled RBC erection penogram (Tc-RBC penogram) coupled with intracavernosal injection of prostaglandin E₁ (PGE₁) was used to evaluate the penile hemodynamic changes during tumescence. As expected, the method is useful to differentiate organic from psychogenic impotence, and arteriogenic from venogenic impotence. Thirty-four patients with psychogenic impotence, 23 patients with arteriogenic impotence, and 27 patients with venogenic impotence were included in the study. A Tc-RBC penogram was performed on each patient after intracavernosal injection of PGE₁. Several parameters calculated from the time-radioactivity curve of the Tc-RBC penogram were used to evaluate hemodynamic changes of the penis. They included (1) the arterial phase: slope and time to peak (TTP), and (2) the venous phase: washout index (WOI). During the arterial phase, the patients with psychogenic and venogenic impotence had higher slope and shorter TTP than those of patients with arteriogenic impotence (p < 0.01). During the venous phase, the patients with psychogenic and arteriogenic impotence had a lower WOI than that of patients with venogenic impotence (p < 0.01). We conclude that the Tc-RBC penogram is a simple, noninvasive, and valuable method for the objective differentiation among psychogenic, arteriogenic, and venogenic impotence.