Author: Ellen Mooney, M.D., Director, Nordic Institute of Virtual Dermatopathology. Chief Editor: Dr Amanda Oakley, Dermatologist, Hamilton, New Zealand, 2014. Updated January 2018.
Whole slide imaging is the software manipulation of digital images of tissue sections that have been scanned at various magnifications. This enables the viewer to zoom in on areas of interest, thereby simulating the examination of glass slides under a traditional microscope. Magnifications of up to × 40 can be achieved.
Whole slide imaging is also called virtual microscopy.
Why use whole slide imaging?
Advantages of using whole slide digital images for microscopic examination of pathology specimens include:
The US Food and Drug Administration (FDA) permitted marketing of whole slide imaging systems for use in pathological diagnosis in April 2017.
Dermatopathology is ideally suited to whole slide imaging for diagnoses, due to high case volume, low slide count and small specimen size in this specialty.
Computers are now readily available in educational institutions and are less costly than microscopes.
Whole slide imaging is also useful in continuing medical education (CME) or continuing professional development (CPD) and external quality assurance (EQA). The incorporation of examinations with integrated multiple-choice questions makes it possible to accrue CME credit online. Accruing CME credit is becoming increasingly important for specialists. In some countries it provides higher salaries, as is currently the case in Europe. In other countries, it is necessary for renewal of licensure and maintenance of specialty certification and is mandatory. The latter is already the case in the USA, along with mandatory certification examinations.
Digital pathology has been proven globally to be a strong tool for CME, CPD and EQA type programmes. Several key organisations, including the College of American Pathologists, the American Society for Clinical Pathology and the Royal College of Pathologists of Australasia, are already using digital pathology to deliver accredited CME exercises. In 2013-2015, the European Academy of Dermatology and Venereology offered to their members a quarterly Clinico-Pathological Self-Assessment Module with whole slide imaging. The American Society of Dermatopathology has an interactive case study of the month , which uses whole slide images. In addition, a number of pathology subspecialty EQA programmes in the UK use digital pathology. The Nordic Institute of Virtual Dermatopathology offers annual Nordic Courses, online modules and CME exam using whole slide imaging and associated software.
Consultation between pathologists and clinicians around the globe is easily manageable. Suitable software allows incorporation of the following with the slide data:
Some institutions use whole slide imaging for filing purposes.
Disadvantages of whole slide imaging may include:
Studies of diagnostic accuracy using whole slide imaging have been done, comparing use of glass slides to digital slides as well as photomicrographs to digital slides. See references below. This is not a comprehensive list.
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