The flow index provides a comprehensive assessment of erectile dysfunction by combining blood flow velocity and vascular diameter (original) (raw)

Dynamic duplex sonography (DUS) is not comprehensive in the evaluation of arteriogenic erectile dysfunction (ED). We introduced a new parameter, the flow index (FI), into the assessment of arteriogenic ED. A retrospective review of a prospective database was conducted. Patients undergoing DUS and pelvic computed tomography angiography for the evaluation of ED were included. The FI was calculated from peak systolic velocity (PSV) and the percentages of pelvic arterial (PLA) stenosis. Correlations between PSV, PLA stenosis, the FI, and erectile function were calculated. Eighty-three patients were included. Compared with PSV, the FI had better correlations with the erection hardness score (EHS) (r s = 0.405, P < 0.001 for FI; r s = 0.294, P = 0.007 for PSV). For EHS < 3, the areas under the ROC curve of FI and PSV were 0.759 and 0.700, respectively. In patients with normal DUS but EHS < 3, PLA stenosis was more severe (62.5% vs. 10.0%, P = 0.015), and the FI was lower (8.35 vs. 57.78, P = 0.006), while PSV was not different. The FI is better than PSV in the evaluation of arteriogenic ED. On the other hand, assessment of the pelvic arterial system should be included in the evaluation of ED. Nearly 50% of men aged 40-70 years suffer from erectile dysfunction (ED) 1. The aetiology of ED can be classified as psychogenic, organic, and mixed. Arterial insufficiency or stenosis, which accounts for approximately 75% of all ED cases, is the major cause in men who have metabolic disorders or cardiovascular diseases 2-8. The cavernous artery, which is derived from the internal iliac artery and its division, including the anterior division of the internal iliac artery, internal pudendal artery, and common penile artery, affects tumescence of the corpus cavernosum and is responsible for erection 9. Dynamic duplex sonography (DUS), which measures the blood flow velocity of the cavernous artery, is commonly used for the evaluation of arteriogenic ED. According to current European Association of Urology (EAU) guidelines, a peak systolic blood flow (PSV) > 30 cm/s, an end-diastolic velocity (EDV) < 3 cm/s, and a resistance index (RI) > 0.8 are generally considered normal 10. On the other hand, multislice computed tomography angiography (CTA), which has become another diagnostic tool for arteriogenic ED, is able to clearly depict the anatomy of the pelvic arterial (PLA) system and accurately measure anatomical stenosis 11-14. Although current measurements from DUS and CTA are commonly used for the evaluation of arteriogenic ED, these measurements may not be comprehensive enough in theory because they provide only partial haemodynamic data, such as "velocity" or "diameter". In fact, several studies have indicated that a diagnosis of arteriogenic ED cannot be made with to the use of PSV alone 15,16. Furthermore, in our experience, we noticed that the results from DUS may not be comparable to clinical observations. Some patients who have normal DUS results still have poor penile hardness after intracavernous injection of prostaglandin E1 (PGE1), suggesting that current measurements from DUS may not be comprehensive enough for diagnosing vasculogenic ED.