Calibration of the Becton Dickinson FocalPoint GS slide profiler is essential for optimal performance: Avoiding the algorithm supersaturation cascade effect pitfall.

BACKGROUND: The MAVARIC study supported the use of the FocalPoint GS (FPGS) imaging system "No Further Review" (NFR) technology for cervical screening and recommended further investigation. A validation study (Nuttall et al.) was performed by Cervical Screening Wales before implementing the NFR slide reporting technology within the cervical screening program in Wales, United Kingdom. METHOD: A total of 45,317 SurePath liquid-based cytology cervical screening samples were submitted for FPGS scanning within four Welsh cytology laboratories between 2006 and 2011. The study, Computer Assisted Evaluation, Screening and Reporting, involved scanning the slides using the FPGS and comparing the results with manual screening performed under established Cervical Screening Wales protocols. RESULTS: An increased number of abnormal cases presented in the NFR reporting category, significantly greater than that previously encountered. This anomaly resulted in higher false-negative rates with potentially life-changing consequences for the screening participant. Subsequent investigation determined that this increase in cases created an algorithm cascade or "sump" effect, which resulted in an unprecedented increased number of samples categorized as NFR. This exceeded the calibration parameters set for the FPGS and was thought to be caused by an increase in the number of younger women attending for screening following the death of a young reality television celebrity from cervical cancer. CONCLUSION: Adequate and timely calibration of FPGS technology is vital for quality assurance of the results produced, particularly following events that may impact on cervical precancer incidence rates. Failure to do so can result in potentially catastrophic screening incidents that are avoidable.

A retrospective validation of the FocalPoint GS slide profiler NFR technology by analysis of interval disease outcomes compared with manual cytology.

BACKGROUND: To the authors' knowledge, published studies reporting on the performance of the FocalPoint GS (FPGS) imaging system have yielded conflicting results to date. However, the results of the MAVARIC study indicated that the FPGS "No Further Review" (NFR) aspect of the technology demonstrated potential and warranted further investigation. The current validation study was performed prior to implementing the NFR slide reporting technology within the routine cervical screening program in Wales, United Kingdom. METHODS: A total of 45,317 SurePath liquid-based cytology cervical screening samples were submitted for FPGS scanning by 4 Welsh laboratories between 2006 and 2011. The current study (Computer Assisted Evaluation, Screening and Reporting [CAESAR]), reports on a comparison between slides categorized as NFR (8130 slides) and slides manually screened as negative (93,473 slides). Both interventions had a subsequent negative quality control screen. RESULTS: The histological outcome rates of cervical intraepithelial neoplasia 2 (CIN-2) (high-grade squamous intraepithelial lesion or worse [HSIL+]) at 2 years and subsequently 3 years after an FPGS NFR result versus a manually screened negative result were compared. Significantly fewer cases were detected in the NFR cohort compared with the manually screened cohort (P = .043 at 2 years and P = .027 at 3 years). When these cases were subcategorized as cancers and precancers, the interval cancer prevalence between NFR and manually screened samples at 2 years and 3 years was similar; however, the interval precancer prevalence for FPGS NFR was significantly lower (P = .023 at 2 years and P = .026 at 3 years) at approximately one-half that of manual screening. CONCLUSIONS: The negative predictive potential of the FPGS NFR technology is higher than that of manual screening, and the technology has quality/throughput benefits to support and enhance a laboratory cervical screening service.