Validating Whole Slide Imaging Systems for Diagnostic Purposes in Pathology

Area of Science:

• Digital Pathology
• Medical Diagnostics
• Clinical Practice Guidelines

Background:

• The original guideline for validating whole slide imaging (WSI) for diagnostic pathology was published in 2013.
• An expert panel was convened by the College of American Pathologists to update these guidelines.
• Updates followed the National Academies of Medicine's standards for developing trustworthy clinical practice guidelines.

Purpose of the Study:

• To systematically review evidence published since the 2013 guideline.
• To provide updated recommendations for validating WSI systems for diagnostic pathology.
• To ensure the reliability and accuracy of digital pathology systems in clinical practice.

Main Methods:

• A systematic literature review was conducted by an expert panel.
• Included were frozen sections, anatomic pathology specimens (biopsies, curettings, resections), and hematopathology cases.
• Cytology cases were excluded; the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach was used.

Main Results:

• Three strong recommendations and nine good practice statements were developed.
• These aim to guide laboratories in validating WSI digital pathology systems.
• Key recommendations focus on validation set size, concordance rates, and washout periods.

Conclusions:

• A validation set of at least 60 cases is reaffirmed.
• Intraobserver diagnostic concordance between WSI and glass slides is crucial.
• Laboratories should aim for >95% overall WSI-glass slide concordance, with reconciliation of all discordances.