Automatic zona pellucida dissection position selection for embryo biopsy in pre-implantation genetic diagnosis

Pre-implantation genetic diagnosis (PGD) is a prenatal diagnosis process that analyses embryos grown in vitro for well-defined genetic defects. In order to obtain one or two blastomeres from an embryo for analysis, embryo biopsy is performed. Embryo biopsy is a process that opens the zona pellucida of an embryo and extracts internal materials, blastomeres in this case, prior to genetic diagnosis. Embryo biopsy can be performed mechanically, chemically or using laser technology. Irrespective of the approach used for embryo biopsy, a suitable zona pellucida opening position must first be selected to prevent the embryo and blastomeres from lysis. The commonly known suitable position for zona pellucida dissection is the perivitelline space, which is the empty space bounded by blastomeres and zona pellucida. Embryo biopsy is a labor intensive and time consuming process that has very stringent skill requirements for embryologists. In this paper, we introduce a single-image automatic zona pellucida dissection position selection algorithm to make embryo biopsy one step closer towards automatic. Through experiment, we have achieved a 93% success rate in successfully recognize a suitable zona cutting position from 37 out of 40 Hoffman Modulation Contrast (HMC) microscopy embryo images.