Automated Non-Invasive Measurement of Sperm Motility and Morphology Parameters

Measuring the motility and morphology parameters of motile cells is important for revealing their functional characteristics. This paper presents automation techniques that, for the first time, enable automated, non-invasive measurement of motility and morphology parameters of individual sperms. Compared to the status quo of qualitative estimation of single sperm's motility and morphology based on embryologists' empirical experience, the automation techniques provide quantitative data in nearly real time. An adapted joint probabilistic data association filter (JPDAF) was used for multi-sperm tracking and tackled challenges of identifying sperms that intersect or have small spatial distances. Since the standard differential interference contrast (DIC) imaging method has side illumination effect which causes inherent inhomogeneous image intensity and poses difficulties for accurate sperm morphology measurement, we integrated total variation norm into the quadratic cost function method, which together effectively removed inhomogeneous image intensity and retained sperm's subcellular structures after DIC image reconstruction. In order to relocate the same sperm of interest identified under low magnification after switching to high magnification, coordinate transformation was conducted to handle the changes in the field of view caused by magnification switch. Experimental results demonstrated an accuracy of 95.6% in sperm motility measurement and errors <10% in morphology measurement.