title: Automatic classification of human sperm head morphology.
abstract: Infertility is a problem that affects up to 15% of couples worldwide with emotional and physiological implications and semen analysis is the first step in the evaluation of an infertile couple. Indeed the morphology of human sperm cells is considered to be a clinical tool dedicated to the fertility prognosis and serves, mainly, for making decisions regarding the options of assisted reproduction technologies. Therefore, a complete analysis of not only normal sperm but also abnormal sperm turns out to be critical in this context. This paper sets out to develop, implement and calibrate a novel methodology to characterize and classify sperm heads towards morphological sperm analysis. Our work is aimed at focusing on a depth analysis of abnormal sperm heads for fertility diagnosis, prognosis, reproductive toxicology, basic research or public health studies.
  
  
  
  We introduce a morphological characterization for human sperm heads based on shape measures. We also present a pipeline for sperm head classification, according to the last Laboratory Manual for the Examination and Processing of Human Semen of the World Health Organization (WHO). In this sense, we propose a two-stage classification scheme that permits to classify sperm heads among five different classes (one class for normal sperm heads and four classes for abnormal sperm heads) combining an ensemble strategy for feature selection and a cascade approach with several support vector machines dedicated to the verification of each class. We use Fisher's exact test to demonstrate that there is no statistically significant differences between our results and those achieved by domain experts.
  
  
  
  Experimental evaluation shows that our two-stage classification scheme outperforms some state-of-the-art monolithic classifiers, exhibiting 58% of average accuracy. More interestingly, on the subset of data for which there is a total agreement between experts for the label of the samples, our system is able to provide 73% of average classification accuracy.
  
  
  
  We show that our system behaves like a human expert; therefore it can be used as a supplementary source for labeling new unknown data. However, as sperm head classification is still a challenging issue due to the uncertainty on the class label of each sperm head, with the consequent high degree of variability among domain experts, we conclude that there are still opportunities for further improvement in designing a more accurate system by investigating other feature extraction methods and classification schemes.
authors.affiliation: Department of Computer Science, University of Chile, Beauchef 851, Santiago, Chile; Laboratory for Scientific Image Analysis, (SCIAN-Lab), Centro de Espermiograma Digital Asistido por Internet (CEDAI SpA), Biomedical Neuroscience Institute (BNI), Program of Anatomy and Developmental Biology, Biomedical Science Institute (ICBM), National Center for Health Information Systems (CENS), Faculty of Medicine, University of Chile, Independencia 1027, Santiago, Chile. Electronic address: vchang@dcc.uchile.cl.
authors.forename: Violeta
authors.initials: V
authors.lastname: Chang
authors.affiliation: Normandie Univ, UNIROUEN, UNIHAVRE, INSA Rouen, LITIS, 76000 Rouen, France. Electronic address: Laurent.Heutte@univ-rouen.fr.
authors.forename: Laurent
authors.initials: L
authors.lastname: Heutte
authors.affiliation: Normandie Univ, UNIROUEN, UNIHAVRE, INSA Rouen, LITIS, 76000 Rouen, France. Electronic address: Caroline.Petitjean@univ-rouen.fr.
authors.forename: Caroline
authors.initials: C
authors.lastname: Petitjean
authors.affiliation: Laboratory for Scientific Image Analysis, (SCIAN-Lab), Centro de Espermiograma Digital Asistido por Internet (CEDAI SpA), Biomedical Neuroscience Institute (BNI), Program of Anatomy and Developmental Biology, Biomedical Science Institute (ICBM), National Center for Health Information Systems (CENS), Faculty of Medicine, University of Chile, Independencia 1027, Santiago, Chile. Electronic address: shartel@med.uchile.cl.
authors.forename: Steffen
authors.initials: S
authors.lastname: Härtel
authors.affiliation: Department of Computer Science, University of Chile, Beauchef 851, Santiago, Chile. Electronic address: nancy@dcc.uchile.cl.
authors.forename: Nancy
authors.initials: N
authors.lastname: Hitschfeld
mesh_terms: D000328:Adult; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D007248:Infertility, Male / Q000000981:diagnostic imaging; D008297:Male; D008853:Microscopy; D055101:Semen Analysis / Q000379:methods*; D013077:Sperm Head / Q000145:classification* / Q000473:pathology*
keywords: Infertility; Sperm head classification; Sperm head morphological descriptor; Two-stage classification