Non-Invasive Time-lapse Measurement of Single Sperm’s Motility and Morphology
Changsheng Dai (1), Zhuoran Zhang (1), Clifford Librach (5), Keith Jarvi (4), Yu Sun (1, 2, 3)
Department of Mechanical and Industrial Engineering, University of Toronto, 2) Institute of Biomaterials and Biomedical Engineering, University of Toronto, 3) Department of Electrical and Computer Engineering, University of Toronto, 4) Division of Urology, Mount Sinai Hospital, 5) CReATe Fertility Centre
Measuring cell motility and morphology is important for revealing their functional characteristics. This work presents automation techniques that enable non-invasive, time-lapse measurement of motility and morphology parameters of single sperms. Compared to the status quo of qualitative estimation of single sperm's motility and morphology manually, the automation techniques provide quantitative data for embryologists to select a single sperm for intracytoplasmic sperm injection (ICSI).
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. The sperm's position after magnification switch was accurately predicted by accounting for the sperm's swimming motion during magnification switch. Experimental results demonstrated an accuracy of 95.6% in sperm motility measurement and an error <10% in morphology measurement.