Tissue characterization of puborectalis muscle from 3D ultrasound

Pelvic floor muscles have the role to prevent pelvic organs’ descent. During crowning the puborectalis muscle (PRM), one of the female pelvic floor muscles, can be damaged. This can potentially cause irreversible muscle trauma and even lead to disconnection from its insertion point i.e. avulsion. Ultrasound imaging allows diagnosis of such trauma based on geometric features. We developed a quantitative ultrasound (QUS) tissue characterization method to obtain information about the state of the tissue of the PRM. The muscle was divided into seven regions of interest (ROIs) and the mean echogenicity, the entropy and the shape parameter of the statistical distribution of gray values were analyzed. This analysis was performed when the muscle was at rest and when it was contracted. We found that, for PRMs with unilateral avulsion compared to undamaged PRMs, the shape parameter was higher (p < 0:01), the entropy was lower(p < 0:01) and mean echogenicity was higher(p = 0:02). This method might be easily applicable on quantifying PRM damage.