Validation of Two Whole Slide Imaging Scanners Based on the Draft Guidelines of the College of American Pathologists
Michael J Thrall. Methodist Hospital, Houston, TX
Background: Whole slide imaging (WSI) converts glass slides into digital images that can be viewed remotely. We have four branch hospitals dependent on a central academic hospital for slide production and expert consultation. We intend to use WSI to avoid glass slide courier delays. We validated using the draft guidelines released by the College of American Pathologists in 2011.
Design: 100 consecutive cases were selected from the following categories that mimic the intended use: consults, frozen sections, malignancies, and special or immunohistochemical stains. Key slides were selected for each case. The slides were scanned at 20x magnification using standard focus and no Z-axis on 2 Ventana iScan Coreo Au scanners (the same 100 cases scanned twice). Pathologists viewed half of the cases as glass slides first and half as WSI first, then switched to the other modality after a delay of at least 3 weeks. Brief history was provided. Diagnoses were documented and intraobserver agreement compiled after the completion of all slide and WSI review.
Results: 23 pathologists participated; most viewed 9 cases. Intraobserver agreement was seen in 165 cases (82.5%), with disagreement in 35 cases (17.5%). Our most striking finding was that 10 cases (5%) showed disagreement between WSI and glass slides because of focal findings not seen in the WSI modality.
|Specimen Source||Glass Slide Diagnosis||WSI Diagnosis||WSI Scanner With Unseen Finding|
|Breast||Atypical lobular hyperplasia||Negative||Both scanners|
|Colon||Focal active colitis||Negative||Both scanners|
|Esophagus||Candida seen||No Candida seen||Both scanners|
|Liver||Iron 1-2+||No increase in iron||Scanner #2|
|Stomach||Suspicious for adenocarcinoma||Negative||Scanner #1|
|Stomach||Chronic active gastritis||Chronic inactive gastritis||Scanner #1|