Factors affecting the shear wave elastic quantitative measurement of penile tissue in rats

BACKGROUND: As a new ultrasound technology, 2-dimensional shear wave elastography (2D-SWE) can evaluate the elastic characteristics of penile tissue. However, no studies have reported the main factors affecting the shear wave elastic quantitative measurement (SWQ) in penile tissue. OBJECTIVES: To analyze the main factors affecting the SWQ reflecting the elastic characteristics of penile tissue by 2D-SWE. METHODS: Twenty healthy male Sprague–Dawley rats (5–60 weeks old) were selected for this study. We performed the 2D-SWE examination on the penis using the Aixplorer ultrasound system, with SWQ as the measurement index. We performed penile immunohistochemistry analysis with the positive area proportion (PAP) of alpha-smooth muscle actin (PAP(S)) and type III collagen fiber (PAP(C)) as the outcomes. Then, we conducted multiple linear regression analysis to explore the correlation of SWQ with PAP(S) and PAP(C) and established the regression equation. RESULTS: The multiple linear regression analysis showed that the linear regression equation (SWQ = 10.376 – 0.05 PAP(S) – 0.07 PAP(C)) was statistically significant (F = 21.153, P < 0.001). The content of smooth muscle cells (SMCs) and collagen fibers was negatively correlated with SWQ, affecting 42.6% of the total variation in SWQ (R(2) = 0.426). CONCLUSIONS: SMCs and collagen fibers are the main factors affecting the SWQ value of penile tissue and the primary tissue components determining the SWQ when using 2D-SWE to quantitatively evaluate the elastic characteristics of penile tissue.