Automated tracking of migrating cells in phase‐contrast video microscopy sequences using image registration

Abstract

This paper is closed access.Analysis of in vitro cell motility is a useful tool for assessing\ud cellular response to a range of factors. However, the majority\ud of cell-tracking systems available are designed primarily for\ud use with fluorescently labelled images. In this paper, five\ud commonly used tracking systems are examined for their\ud performance compared with the use of a novel in-house celltracking\ud system based on the principles of image registration\ud and optical flow. Image registration is a tool commonly used\ud in medical imaging to correct for the effects of patient motion\ud during imaging procedures and works well on low-contrast\ud images, such as those found in bright-field and phase-contrast\ud microscopy. The five cell-tracking systems examined were\ud Retrac, a manual tracking system used as the gold standard;\ud CellTrack, a recently released freely downloadable software\ud system that uses a combination of tracking methods; ImageJ,\ud which is a freely available piece of software with a plug-in\ud for automated tracking (MTrack2) and Imaris and Volocity,\ud both commercially available automated tracking systems. All\ud systemswere used to track migration of human epithelial cells\ud over ten frames of a phase-contrast time-lapse microscopy\ud sequence. This showed that the in-house image-registration\ud system was the most effective of those tested when tracking\ud non-dividing epithelial cells in low-contrast images, with a\ud successful tracking rate of 95%. The performance of the\ud tracking systems was also evaluated by tracking fluorescently\ud labelled epithelial cells imaged with both phase-contrast and\ud confocal microscopy techniques. The results showed that\ud using fluorescence microscopy instead of phase contrast does\ud improve the tracking efficiency for each of the tested systems.\ud For the in-house software, this improvement was relatively small (<5%difference in tracking success rate),whereasmuch\ud greater improvements in performance were seen when using\ud fluorescence microscopy with Volocity and ImageJ