New paper in Fertility and Sterility, 2015:

Interferometric phase microscopy for label-free morphological evaluation of sperm cells

Miki Haifler, Pinhas Girshovitz, Gili Band, Gili Dardikman, Igal Madjar, and Natan T. Shaked

Abstract:

Objective: To compare label-free interferometric phase microscopy (IPM) to label-free and label-based bright-field microscopy (BFM) in evaluating sperm cell morphology. This comparison helps in evaluating the potential of IPM for clinical sperm analysis without staining.

Design: Comparison of imaging modalities.

Setting: University laboratory.

Patient(s): Sperm samples were obtained from healthy sperm donors. Intervention(s): We evaluated 350 sperm cells, using portable IPM and BFM, according to World Health Organization (WHO) criteria. The parameters evaluated were length and width of the sperm head and midpiece; size and width of the acrosome; head, midpiece, and tail configuration; and general normality of the cell.

Main Outcome Measure(s): Continuous variables were compared using the Student’s t test. Categorical variables were compared with the X^2 test of independence. Sensitivity and specificity of IPM and label-free BFM were calculated and compared with label-based BFM.

Result(s): No statistical differences were found between IPM and label-based BFM in the WHO criteria. In contrast, IPM measurements of head and midpiece width and acrosome area were different from those with label-free BFM. Sensitivity and specificity of IPM were higher than those with label-free BFM for the WHO criteria.

Conclusion(s): Label-free IPM can identify sperm cell abnormalities, with an excellent correlation with label-based BFM, and with higher accuracy compared with label-free BFM. Further prospective clinical trials are required to enable IPM as part of clinical sperm selection procedures.

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(a) An interferogram obtained using IPM. The sample is still barely seen. However, the OPD information is encoded into the bend of the interference fringes, as can be seen from the enlarged region of interest in (b). (c) The OPD map of the same sperm cell, as digitally calculated from the interferogram shown in (a). All the main morphological features of the cell are discernable. (c, e) Imaging of a sperm cell with an acrosomal vacuole, using: (d) label-based BFM, and (e) label-free IPM. The vacuole is clearly seen as a defect in the OPD map of the IPM image. BFM = bright-field microscopy; IPM = interferometric phase microscopy; OPD = optical path delay. Elsevier 2015(c).