Abstract
Abstract Introduction Percentage of corporal smooth muscle and corporal connective tissue within penile erectile tissue was determined by histomorphometric assessment of biopsies removed during penile prosthesis insertion. Previous studies have shown that these histomorphometry data correlated with pre-operative pharmacocavernosometry testing during complete smooth muscle relaxation. At 50-55% corporal connective tissue (CCT) content, corporal veno-occlusive function was found to be normal. When CCT content was 60-75%, corporal veno-occlusive function significantly worsened in an exponential relationship. Above 75% CCT content, there was no recordable corporal veno-occlusive function. Pre-operative grayscale ultrasonography (GUS) during complete smooth muscle relaxation is a less invasive in-office diagnostic assessment for ED than pharmacocavernosometry. It has been previously reported that hypoechoic areas in GUS are indicative of regions of erectile tissue fibrosis. Objective We examined for the first time whether findings on pre-operative GUS could correlate with histomorphometry data on CCT content in the same manner that pharmacocavernosometry correlated with CCT content. Methods Pre-operative proximal shaft axial plane GUS images were obtained using a 15.4 MHz probe (Aixplorer), gain setting 45%, dynamic range 70 dB. Percent hypoechoic area within the corporal cavernosa was assessed by computer-assisted image analysis using Image J (Fig. 1). During penile prosthesis surgery, erectile tissue from the proximal shaft was biopsied for histological analysis (n = 12). Formalin-fixed (10%), paraffin-embedded tissue sections (5 μm) were stained with Masson’s trichrome. Photomicrographs were analyzed by Image J using the Masson trichrome vector of the color deconvolution plugin. Results Percent hypoechoic area was poorly correlated to percent CCT area by linear regression analysis (r2 = 0.287). However, a non-linear regression model, an exponential growth curve, provided a better fit (r2 = 0.672) with an inflection point at 40% CCT area (Fig. 2). The abrupt shift is similar to the previously reported corporal veno-occlusive function curve using pharmacocavernosometry. Conclusions Estimation of percent hypoechoic area on pre-operative GUS images during complete smooth muscle relaxation may be a useful, non-invasive assessment of CCT content to predict corporal veno-occlusive function. Larger cohorts of ED patients are needed to verify the clinical utility of GUS. Disclosure No.
Published Version
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