Sham-Controlled Prospective Study Characterizing Erectile Tissue Ultrasound Changes Resulting From Penile LiSWT

The primary goal of this single blind, prospective sham-controlled clinical trial is to assess safety and efficacy of low intensity shockwave therapy (LiSWT) to improve erectile function in men 21-80 years of age with erectile dysfunction naive to radial ballistic acoustic wave and LiSWT. The main questions it aims to answer are: * Does homogeneity/inhomogeneity of corporal cavernosal tissue improve using Grayscale ultrasound (GUS) when comparing sham to active treatment groups? * Do peak systolic velocity (PSV) and end diastolic velocity (EDV) improve using color duplex Doppler ultrasound when comparing sham to active treatment groups? * Do the International Index of Erectile Function (IIEF), its erectile function domain (IIEF-EF) and question 3 of the Sexual Encounter Profile (SEP) improve comparing sham to active treatment groups?

This is a single site sham-controlled clinical trial to be conducted at San Diego Sexual Medicine in San Diego, California. Subjects meeting inclusion and exclusion criteria will be randomized to one of two arms, each 2:1 active to sham, treated in 3-week cycles. Arm 1 consists of 5000 shocks the first week and two weeks off for each of three treatment cycles. Arm 2 is made up of 5000 shocks the first week and 3000 active shocks the second and third weeks followed by three weeks without treatment, and then 5000, 3000 and 3000 shocks again over the next three weeks. Each of these is followed by the first follow-up visit at 20 weeks after the first treatment, when GUS and DUS is repeated and validated instruments completed, at which time treatment will be unblinded. SEP diaries will be completed during sexual activity in the screening period and during the 4 weeks prior to the follow up visit. Those subjects assigned to sham will be crossed over to the opposite arm for active treatment (arm 1 sham goes to arm 2 open label and arm 2 sham to arm 1 open label) and begin active treatment with decreased intervals between shocks and therefore decreased number of shocks needed, with 3500 rather than 5000 shocks and 2000 rather than 3000 shocks at a lower frequency at that visit after completing the follow up procedures. Subjects assigned initially to the active arm will have a second follow up 32 weeks after the first treatment, and complete SEP diaries during the 4 weeks preceding this visit. GUS and DUS is performed and validated instruments completed at the last follow up.