A validation study of the FocalPoint GS imaging system for gynecologic cytology screening.

BACKGROUND

Studies of the performance of the automated FocalPoint Guided Screening (FPGS) imaging system in gynecologic cytology screening relative to manual screening have yielded conflicting results. In view of this uncertainty, a validation study of the FPGS was conducted before its potential adoption in 2 large laboratories in Ontario.

METHODS

After an intense period of laboratory training, a cohort of 10,233 current and seeded abnormal slides were classified initially by FPGS. Manual screening and reclassification blinded to the FPGS results were then performed. Any adequacy and/or cytodiagnostic discrepancy between the 2 screening methods subsequently was resolved through a consensus process (truth). The performance of each method's adequacy and cytodiagnosis vis-a-vis the truth was established. The sensitivity and specificity of each method at 4 cytodiagnostic thresholds (atypical squamous cells of undetermined significance or worse [ASC-US+], low-grade squamous intraepithelial lesion or worse [LSIL+], high-grade squamous intraepithelial lesion or worse [HSIL+], and carcinoma) were compared. The false-negative rate for each cytodiagnosis was determined.

RESULTS

The performance of FPGS in detecting carcinoma, HSIL+, and LSIL+ was no different from the performance of manual screening, but the false-negative rates for LSIL and ASC-US were higher with FPGS than with manual screening.

CONCLUSIONS

The results from this validation study in the authors' laboratory environment provided no evidence that FPGS has diagnostic performance that differs from manual screening in detecting LSIL+, HSIL+, or carcinoma.