A novel algorithm for assessment of penile fibrosis in men with erectile dysfunction
Goldstein, I1; Rubin, RS2; Winter, AG2
1: Alvarado Hospital, USA; 2: San Diego Sexual Medicine, USA
Objectives: Corporal erectile tissue fibrosis is a significant pathophysiologic component of erectile dysfunction (ED), however current ultrasound-based penile imaging protocols do not directly assess it. Veno-occlusive dysfunction, quantified by elevated end diastolic velocity (EDV) of the penile cavernosal artery, a common surrogate for fibrosis, cannot identify site-specific lesions. In addition, EDV may only be abnormal in advanced disease states. Signal analysis of heterogeneity on B-mode ultrasound of other venous-sinus based tissue (i.e., liver) has been correlated to clinical fibrosis-based disease states. We developed a B-mode ultrasonographic imaging protocol for assessment of penile corporal heterogeneity that correlates to EDV to serve as a foundation for processing and categorizing corporal fibrosis images.
Material and Methods: Following pharmacologic erection, B-mode ultrasound (Aixplorer 15.4 mHz transducer) was performed. Images were captured in the axial plane at the proximal, mid, and distal shaft with gain of 45%, 55%, 65% and dynamic range 70 kB, followed by gain 30% (dynamic range 30-40 kB) for high contrast image. Subjects were grouped into homogenous (Group 1, n=42) mildly heterogeneous (Group 2, n=64), and moderate-severely heterogeneous (Group 3, n=53) by gross assessment of corporal tissue heterogeneity by the clinician. High-reliability assessment of EDV was performed using combined color and pulsed-wave (UltraFastTM) Doppler of the cavernosal artery.
Results: 159 consecutive duplex Doppler ultrasound studies of men with erectile dysfunction (ED) (mean age 38.7 yr, IIEF score 13) were reviewed. Mean right cavernosal artery EDV was 0.41cm/s, 1.0cm/s, and 6.1cm/sec and mean left cavernosal artery EDV was 0.40cm/s, 0.9cm/s, and 5.9cm/s for groups 1, 2, and 3, respectively. Mean difference in EDV between groups 2 and 3 was -5.10, 95% CI [-1.05, -9.16] right, -5.04, 95% CI [-1.65, -8.44] left. Mean difference in EDV between groups 1 and 3 was -5.72, 95% CI [-1.19, -10.25] right, -5.59, 95% CI [-1.79, -9.38] left.
Conclusions: Increased corporal tissue heterogeneity on high-resolution B-mode ultrasound corresponds to higher EDV, a surrogate for increased fibrosis, and may serve as an early marker of ED that is location/lesion specific. Future studies should quantify fibrosis severity using image processing in a user-independent fashion.
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