Medical education in the digital age: Digital whole slide imaging as an e-learning tool

The visual aids used in teaching and lecturing to students have clearly evolved over the last several decades. Illustrations on paper were replaced by carousels full of photographic slides, which in turn have been supplanted by Powerpoint™ presentations. At an arguably much slower pace, the method of teaching microscopic anatomy to students of the healthcare professions is also changing. For the majority of medical students graduating before 2000, the microscope and accompanying boxes of glass slides were the standard tools for learning both histology and pathology. Studying for exams also included reviewing kodachromes showing static fields-of-view at predetermined magnifications. Both of these methods of learning required the student to be physically present on campus. Pathology residents, when not learning at the microscope with the attending pathologist, must rely on teaching sets of glass slides that cannot leave the department. Group learning must either be done at a multiheaded microscope (which many times has fewer heads than people present) or by use of video technology attached to the microscope. With the advent of digital whole slide imaging (WSI) over the past several years, there is an opportunity to revolutionize the way teaching and learning are done for all students of medicine including doctors, nurses, medical technicians, histology technicians, cytology technicians, and others. Comparison of Digital Whole Slide Images with Glass Slides There are many advantages to using WSI when compared with traditional glass slides [Table 1]. Digital images can be standardized; all students will study the exact same tissue section. Sections on glass slides are inherently variable in quality and content.[1] Although admittedly subtle in some cases, these variabilities can be eliminated with digital imaging. The quality of the image can also be indefinitely maintained compared to glass slides that are vulnerable to fading, breaking, and vanishing.[2] One very helpful aspect of digital images is the use of a thumbnail image. As students are examining the image at higher magnification, they can always refer to the thumbnail for orientation.[3] This obviously is impossible with glass slides. Glass slides cannot be easily annotated with any precision, relying on relatively crude “dotting” for the purposes of highlighting a certain area of the slide. Digital images can have multiple annotations including arrows, circles, text, etc. placed exactly where needed. Portability is another benefit of using digital images. The use of microscopes obligates a student to remain on campus in order to study, review, etc. With WSI loaded onto a web-based server, study can occur wherever and whenever the student wishes.[2] WSI also makes simultaneous viewing of a particular field-of-view possible; a major advantage over glass slides. Viewing the image on a common computer monitor encourages discussion and collaboration between classmates.[1] Finally, storage of WSI becomes a matter of having enough server memory. As server space becomes less and less expensive, the cost and effort of storing and maintaining both the microscopes and glass slide sets will become comparatively more burdensome.[3] Some disadvantages that have become apparent with WSI include the dependence of the image quality on monitor resolution and the challenge of scanning tissue sections that have artifacts such as folds, etc.[3] Judicious choice of an acceptable non-cost prohibitive monitor is essential for an accurate image. As digital scanners become “smarter”, the flaws in a slide will likely become less of an issue. Table 1 Benefits of digital slide imaging