Students' performance during practical examination on whole slide images using view path tracking

Whole slide images (WSIs) used in medical education can provide new insights into how histological slides are viewed by students. We created software infrastructure which tracks viewed WSI areas, used it during a practical exam in oral pathology and analyzed collected data to discover students' viewing behavior.

A view path tracking solution, which requires no specialized equipment, has been implemented on a virtual microscopy software platform (WebMicroscope, Fimmic Ltd, Helsinki, Finland). Our method dynamically tracks view paths across the whole WSI area and all zoom levels, while collecting the viewing behavior data centrally from many simultaneous WSI users. We used this approach during the exam to track how all students (N = 88) viewed WSIs (50 per student) when answering exam questions (with no time limit). About 74,000 records with information about subsequently displayed WSI areas were saved in the central database. Gathered data was processed and analyzed in multiple ways. Generated images and animations showed view fields and paths marked on WSI thumbnails, either for a single student or multiple students answering the same question. A set of statistics was designed and implemented to automatically discover certain viewing patterns, especially for multiple students and WSIs. Calculated metrics included average magnification level on which a WSI was displayed, dispersion of view fields, total viewing time, total number of view fields and a measure depicting how much a student was focused on diagnostic areas of a slide.

Generated visualizations allowed us to visually discover some characteristic viewing patterns for selected questions and students. Calculated measures confirmed certain observations and enabled generalization of some findings across many students or WSIs. In most questions selected for the analysis, students answering incorrectly tended to view the slides longer, go through more view fields, which were also more dispersed - all compared to students who answered the questions correctly.

Designed and implemented view path tracking appeared to be a useful method of uncovering how students view WSIs during an exam in oral pathology. Proposed analysis methods, which include visualizations and automatically calculated statistics, were successfully used to discover viewing patterns.

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/13000_2014_208.