Value of power Doppler sonography in the investigation of erectile dysfunction

The poor sensitivity of conventional color-coded Doppler sonography (CCD) for low-flow signals limits its use for investigating patients with erectile dysfunction. Power Doppler sonography (PD) has recently been described for enhanced visualization of the microcirculation. Aim of this study was to determine the value of PD to demonstrate penile vascular pathophysiology as compared with conventional techniques.

33 consecutive men with erectile dysfunction were investigated using the standard workup with conventional CCD and cavernosography before and after prostaglandin E(1) intracavernosal injection. Patients were subdivided into an arteriogenic, a venogenic, or a psychogenic group according to findings in the standard diagnostic workup. PD was used in addition to the standard protocol to demonstrate microcirculation, arterial blood flow, and venous leakage. The accuracy of the diagnosis obtained by PD and response to intracavernosal injection was compared with the clinical outcome in these groups at 6 months.

PD was found to be superior to CCD in visualizing cavernosal microcirculation. In addition, arterial flow at basal peak systolic velocity was demonstrated in all patients with PD, whereas a signal sufficient for evaluation was obtained with CCD in only 69.7% (23/ 33). No significant difference in the maximal peak systolic velocity was noted using either PD or CCD. The positive predictive value of PD for venous leakage was poor (60%) when compared with cavernosography. PD used in conjunction with the response to intracavernosal injection was found to reliably predict the clinical outcome in the arteriogenic (p = 0.0007), the venogenic (p = 0.005), and the psychogenic group (p = 0.0002).

Our data indicate that PD improves the evaluation of penile microcirculation and arterial function, but fails to reliably demonstrate venous leakage alone. Nevertheless, in most patients cavernosography could have been avoided by the aid of PD, since the underlying pathology can be calculated at a high predictive value without the need of further invasive tests. Therefore, with the aid of PD, the morbidity for patients being investigated for erectile dysfunction can be significantly reduced.