112 Vibro-elastography: A Novel, Non-invasive Tool for Evaluating Penile Fibrosis

Abstract

Penile duplex Doppler ultrasonography (PDDU) is an objective, non-invasive exam that allows characterization of the vascular status of the penis. However, this method has notable limitations and is relatively limited in its ability to identify smooth cavernosal fibrosis with commonly underlies organic erectile dysfunction (ED). Penile ultrasound vibro-elastography (PUVE) is a novel technology utilizing ultrasound and fluid mechanics that allows for non-invasive evaluation of corporal viscoelasticity, which is hypothesized to correlate with the severity of penile fibrosis. Herein, we aim to describe the principles underlying PUVE and its application in the evaluation of penile fibrosis as it pertains to erectile dysfunction. A device known as a handheld shake (Model: FD-142, Labworks Inc. Costa Mesa, Ca, USA) is used to create a 0.1-second harmonic vibration which is applied to the penile shaft using various frequencies (100, 150, and 200 Hz). An ultrasound probe positioned on the contralateral side is used to measure the resultant shear-wave velocity as it propagates through the corporal tissue. With this data, the corporal tissue viscosity and elasticity can be calculated. We performed a pilot study of 10 men with ED and/or Peyronie’s Disease to evaluate the clinical utility of PUVE. PUVE was performed on subjects in the flaccid penile state to obtain baseline measurements of the corporal tissue. Patients subsequently underwent intracavernosal injection until a fully rigid erection was achieved (or maximum of 1 mL administered). Repeat PUVE assessments were performed in the same manner on the erect penis. PDDU was also performed to measure peak systolic velocity (PSV), end-diastolic velocity, and resistive index. Corporal viscosity and elasticity were compared between the flaccid and erect penis. Penile viscosity and elasticity were also compared to PSV and Framingham risk scores which serve as a correlate for cardiovascular risk stratification.