Relevance of the College of American Pathologists guideline for validating whole slide imaging for diagnostic purposes to cytopathology

Abstract

Whole slide imaging (WSI) allows pathologists to view virtual versions of slides on computer monitors. With increasing adoption of digital pathology, laboratories have begun to validate their WSI systems for diagnostic purposes according to reference guidelines. Among these the College of American Pathologists (CAP) guideline includes three strong recommendations (SRs) and nine good practice statements (GPSs). To date, the application of WSI to cytopathology has been beyond the scope of the CAP guideline due to limited evidence. Herein we systematically reviewed the published literature on WSI validation studies in cytology. A systematic search was carried out in PubMed-MEDLINE and Embase databases up to November 2021 to identify all publications regarding validation of WSI in cytology. Each article was reviewed to determine if SRs and/or GPSs recommended by the CAP guideline were adequately satisfied. Of 3963 retrieved articles, 25 were included. Only 4/25 studies (16%) satisfied all three SRs, with only one publication (1/25, 4%) fulfilling all three SRs and nine GPSs. Lack of a suitable validation dataset was the main missing SR (16/25, 64%) and less than a third of the studies reported intra-observer variability data (7/25, 28%). Whilst the CAP guideline for WSI validation in clinical practice helped the widespread adoption of digital pathology, more evidence is required to routinely employ WSI for diagnostic purposes in cytopathology practice. More dedicated validation studies satisfying all SRs and/or GPSs recommended by the CAP are needed to help expedite the use of WSI for primary diagnosis in cytopathology.

Digital cytology: Current status and future prospects

“…A recent large meta‐analytical studied showed that out of 25 studies on cytopathology, 4 (16%) studies followed the strong recommendations and only one (4%) study followed both strong and good practice guidelines of CAP. The authors concluded that rigorous and well‐designed studies on cytology are needed to generate robust evidences for the successful implementation of the WSI for the primary diagnosis in cytology 25 …”

“…The authors concluded that rigorous and well-designed studies on cytology are needed to generate robust evidences for the successful implementation of the WSI for the primary diagnosis in cytology. 25…”

BestCyte® primary screening of 500 ThinPrep Pap Test thin-layers: 3 Cytologists’ Interobserver diagnostic concordance with predicate manual microscopy relative to Truth Reference diagnoses defining NILM, ASCUS+, LSIL+, and ASCH+ thresholds for specificity, sensitivity, and equivalency grading

“…These studies honored various Recommendations and Good Practice Statements proposed for digital system assessment and validation. 32 , 33 , 34 Accordingly, concurrent with formal clinical trials and system deployment in the clinical setting, BestCyte may be subjected to a rigorous suite of exercises relative to known cases and diagnoses involving primary screening and senior reviewer cytologists (i.e., cytotechnologists) and pathologists, 35 , 36 and the quality control and assurance workflows applicable in diagnostic practice. All abnormal cases in the 500 ThinPrep PCS were formally reported by a pathologist in 2016.…”

Validation of cytopathology specimens for digital pathology

“…A recently published systematic review of papers dealing with the validation of cytology for use in digital analysis showed that only a minority of the published papers followed all CAP recommendations, including both SRs and GPSs. 14 Since the present study investigated the implementation of the digital analysis of cytological samples in a CAP-accredited laboratory, all processes had to be performed rigorously, following CAP recommendations. As previously stated, because these recommendations do not address specific cytopathological issues, adjustments were made to allow for the practical considerations associated with the analysis of cytological samples, such as defining agreement and final concordance rates.…”

“…[6][7][8] It has been widely used for telecytology and rapid on-site evaluation, 9,10 but few papers have compared actual diagnoses obtained using whole slide images (WSIs) with those obtained using glass slides [11][12][13] , and even fewer have followed the CAP guidelines for the validation of WSI in a clinical setting. 14 In the current study, we aimed to validate different types of cytological preparations for routine clinical use in digital pathology, following the 2021 CAP guidelines, and also to highlight specific characteristics and difficulties involved in the use of such preparations in clinical everyday digital sign-out.…”