Keywords: سونوگرافی، داپلر، رنگ; penis; impotence, vasculogenic; ultrasonography, Doppler, color; phosphodiesterase 5 inhibitors; treatment failureBMI, body mass index; CDDU, color Doppler duplex ultrasound; CVOD, cavernous venous occlusive disease; ED, erectile dysfunction; EDV, end dia