Can we change the way we screen?: The ThinPrep Imaging System®

ThinPrep® imaging system-assisted vs manual screening of urinary cytology slides in the detection of the "suspicious for high-grade urothelial carcinoma" category

BACKGROUND

The ThinPrep® Imaging System (TIS) is a Food and Drug Administration-approved review system for cervical cytopathology, where it has been shown to increase performance over manually reviewed slides. Application of the TIS to urinary cytology has only been reported in a single study, in 2013.

METHODS

We aimed to compare the agreement of two cytotechnologists' and a pathologist's manual screening (dots) with the fields of view (FOVs) selected by the TIS. We also aimed to track cases in which the TIS could identify missed abnormals and reduce the false-negative fraction. Electronically marked TIS fields (EMTFs) suspicious for high-grade urothelial carcinoma (SHGUC) were controlled by follow-up cystoscopy and histology, where available.

RESULTS

A total of 826 consecutive specimens were studied. Of those, 94 (11.4%) were unreadable by the TIS. There were 710 possible comparisons, of which 380 (53.5%) received no dot after manual screening. Of the 330 remaining slides, 149 (45.1%) had at least one dot matching with the TIS FOVs. After TIS reading, EMTFs were noted in 13 of 636 (2.0%) negative cytology cases. Surveillance showed that 3/13 (23.1%, 0.4% of the 710 possible comparisons) of those cases matched with high grade urothelial carcinoma (HGUC), whereas 6/13 (46.1%, 0.8% of the 710 possible comparisons) had negative follow-up at 24 months, and 4/13 (30.8%) were lost for follow-up.

CONCLUSION

The TIS increases the detection rate of SHGUC cells, potentially leading to a slight decrease in the false-negative fraction, but at the expense of a slight but larger increase in the number of false-positive cases. These findings stress the importance of a careful approach to the evaluation of the FOVs.

The added value of digital imaging to reflex cytology for triage of high‐risk human papillomavirus positive self‐sampled material in cervical cancer screening: a prospective cohort study

OBJECTIVE

Cytology performed directly on hrHPV-positive self-samples (reflex cytology) is feasible and for women with abnormal cytology, an additional cytology test at the general practitioner could be omitted. The aim of this study is to assess the added value of digital imaging (ThinPrep® Imaging System) on the clinical utility of reflex cytology by reducing screening error.

DESIGN

A secondary analysis of a prospective cohort study.

SETTING

One of five Dutch screening laboratories.

POPULATION

Women tested hrHPV-positive on self-samples between December 2018 and August 2019.

METHODS

Self-samples were used for reflex cytology with and without digital imaging. The follow-up data (cytological and histological results within 1 year of follow-up) were obtained through the Dutch Pathology Registry (PALGA).

MAIN OUTCOME MEASURES

Test performance of the reflex cytology was determined by comparing it with physician-collected follow-up results.

RESULTS

The sensitivity for detecting abnormal cells by reflex cytology on self-samples increased significantly from 26.3% (42/160; 95% confidence interval [CI] 19.6-33.8) without digital imaging to 35.4% (56/158; 95% CI 28-43.4) with digital imaging (P < 0.05) without compromising specificity. Importantly, 41.7% of women with ≥CIN2 (35/84) and 45.6% with ≥CIN3 (26/57) were detected by reflex cytology with digital imaging on hrHPV-positive self-samples.

CONCLUSION

Digital imaging is of added value to reflex cytology on hrHPV-positive self-samples with a 9% increase in sensitivity. If reflex cytology on self-samples analysed with digital imaging had been implemented in the screening programme, 35.4% of the hrHPV-positive women with abnormal cytology on additional physician-collected samples could have been referred directly for colposcopy.

CelLock TM: an innovative standardized cell-block preparation procedure

The CelLock™ procedure kit is used to collect and prepare cellular specimens such as fine needle aspirates (FNA), cytology specimens, cultured cells, small tissue biopsies, and samples with scant tissue fragments or cells into a paraffin cell-block. This cell-block can be used for subsequent microtomy and staining using hematoxylin and eosin (H&E), special stains, immunohistochemistry (IHC), and applicable molecular techniques such as in situ hybridization (ISH). CelLock is a standardized method that provides optimal receipt, preservation, preparation, and processing of cell-blocks which, contain virtually all of the submitted specimens and are able to be embedded and sectioned in a reproducible fashion. The specimen contained within the cell-block is preserved such that all the cellular protein and genetic information is available for histological and ancillary testing.

A Study of Thyroid Fine Needle Aspiration of Follicular Adenoma in the "Atypia of Undetermined Significance" Bethesda Category Using Digital Image Analysis

Background

Originally designed for computerized image analysis, ThinPrep is underutilized in that role outside gynecological cytology. It can be used to address the inter/intra-observer variability in the evaluation of thyroid fine needle aspiration (TFNA) biopsy and help pathologists to gain additional insight into thyroid cytomorphology.

Methods

We designed and validated a feature engineering and supervised machine learning-based digital image analysis method using ImageJ and Python scikit-learn . The method was trained and validated from 400 low power (100x) and 400 high power (400x) images generated from 40 TFNA cases.

Result

The area under the curve (AUC) for receiver operating characteristics (ROC) is 0.75 (0.74–0.82) for model based from low-power images and 0.74 (0.69–0.79) for the model based from high-power images. Cytomorphologic features were synthesized using feature engineering and when performed in isolation, they achieved AUC of 0.71 (0.64–0.77) for chromatin, 0.70 (0.64–0.73) for cellularity, 0.65 (0.60–0.69) for cytoarchitecture, 0.57 (0.51–0.61) for nuclear size, and 0.63 (0.57–0.68) for nuclear shape.

Conclusion

Our study proves that ThinPrep is an excellent preparation method for digital image analysis of thyroid cytomorphology. It can be used to quantitatively harvest morphologic information for diagnostic purpose.

Computational Cytology: Lessons Learned from Pap Test Computer-Assisted Screening

BACKGROUND

In the face of rapid technological advances in computational cytology including artificial intelligence (AI), optimization of its application to clinical practice would benefit from reflection on the lessons learned from the decades-long journey in the development of computer-assisted Pap test screening.

SUMMARY

The initial driving force for automated screening in cytology was the overwhelming number of Pap tests requiring manual screening, leading to workflow backlogs and incorrect diagnoses. Several companies invested resources to address these concerns utilizing different specimen processing techniques and imaging systems. However, not all companies were commercially prosperous. Successful implementation of this new technology required viable use cases, improved clinical outcomes, and an acceptable means of integration into the daily workflow of cytopathology laboratories. Several factors including supply and demand, Food and Drug Administration (FDA) oversight, reimbursement, overcoming learning curves and workflow changes associated with the adoption of new technology, and cytologist apprehension, played a significant role in either promoting or preventing the widespread adoption of automated screening technologies. Key Messages: Any change in health care, particularly those involving new technology that impacts clinical workflow, is bound to have its successes and failures. However, perseverance through learning curves, optimizing workflow processes, improvements in diagnostic accuracy, and regulatory and financial approval can facilitate widespread adoption of these technologies. Given their history with successfully implementing automated Pap test screening, cytologists are uniquely positioned to not only help with the development of AI technology for other areas of pathology, but also to guide how they are utilized, regulated, and managed.

Comparative analysis of cervical cytology screening methods and staining protocols for detection rate and accurate interpretation of ASC-H: Data from a high-volume laboratory in Turkey

BACKGROUND

This study evaluated the effectiveness of the ThinPrep(®) Imaging System (TIS) and ThinPrep(®) Pap Stain (TPPS). A comparative analysis was conducted to determine the detection rates of atypical squamous cells, cannot exclude high-grade squamous intraepithelial lesion (ASC-H), the ASC:squamous intraepithelial lesion (SIL) ratio, biopsy follow-up for ASC-H in terms of the screening method used (manual screening [MS] vs. TIS screening [TISS]) and the staining protocol (regular Pap stain [RPS] vs. TPPS).

METHODS

This study was performed over two periods. The RPS period included manually screened slides, whereas the TPPS period included TIS + manually screened slides. All data from the study periods were compared using statistical analysis.

RESULTS

The detection rate of ASC-H was significantly higher during the TPPS period than during the RPS period (0.49% vs. 0.23%); this finding is in contrast to the insignificant difference between the screening method periods. The positive predictive value (PPV) of ASC-H cytodiagnosis for cervical intraepithelial neoplasia of grade 2 or more severe histologies was significantly different between manually screened and TIS slides (22.10% vs. 38.55%), in contrast to an insignificant difference between RPS and TPPS periods (37.14% vs. 29.77%).

CONCLUSION

Implementation of the TIS did not change the ASC-H detection rates appreciably. However, the new technology improved PPV for ASC-H cytodiagnosis and enabled the detection of true disease. Our laboratory statistics indicate that the TPPS is not a superior staining protocol and did not increase our diagnostic accuracy for ASC-H compared with RPS.

Semi-automatic segmentation and classification of Pap smear cells

Cytologic screening has been widely used for detecting the cervical cancers. In this study, a semiautomatic PC-based cellular image analysis system was developed for segmenting nuclear and cytoplasmic contours and for computing morphometric and textual features to train support vector machine (SVM) classifiers to classify four different types of cells and to discriminate dysplastic from normal cells. A software program incorporating function, including image reviewing and standardized denomination of file names, was also designed to facilitate and standardize the workflow of cell analyses. Two experiments were conducted to verify the classification performance. The cross-validation results of the first experiment showed that average accuracies of 97.16% and 98.83%, respectively, for differentiating four different types of cells and in discriminating dysplastic from normal cells have been achieved using salient features (8 for four-cluster and 7 for two-cluster classifiers) selected with SVM recursive feature addition. In the second experiment, 70% (837) of the cell images were used for training and 30% (361) for testing, achieving an accuracy of 96.12% and 98.61% for four-cluster and two-cluster classifiers, respectively. The proposed system provides a feasible and effective tool in evaluating cytologic specimens.

Effect of Thin Prep(®) imaging system on laboratory rate and relative sensitivity of atypical squamous cells, high-grade squamous intraepithelial lesion not excluded and high-grade squamous intraepithelial lesion interpretations

Introduction:

Automated screening of Thin Prep^® Papanicolaou Tests has become increasingly common in clinical practice. Increased productivity has initiated laboratory use of the Thin Prep^® Imaging System (TIS). Increased sensitivity is a potential additional benefit of TIS. Published studies have shown an increase in discovery of dysplastic cells. This study evaluates the effect of TIS on the incidence of atypical squamous cells high-grade squamous intraepithelial lesion not excluded (ASC-H) and high-grade squamous intraepithelial lesion (HGSIL) results on Thin Prep^® Pap Tests by comparing TIS-assisted and manual screening findings and the diagnoses on subsequent follow-up in a screening population over a 1-year time period.

Materials and Methods:

A compilation of all ASC-H and HGSIL cases was prepared by conducting a computerized search over a 1-year period (7/06-6/07). The accumulated cases include Thin Prep Pap tests that were both TIS and manually screened. Follow-up results of cytologic and histologic cervical specimens were obtained for a time period extending to 2010. Interpretation utilizing TIS was in place 10 months prior to the study's initiation.

Results:

During the study period 70,522 Pap tests were performed in our laboratory. One third (33%) of Pap tests were screened with assistance of TIS. Manual screening was performed on 47,380 Pap tests of which 153 (0.32%) were interpreted as ASC-H and 164 (0.35%) were interpreted as HGSIL. During the same time period automated screening (TIS) was performed on 23,111 Pap tests. Interpretation of 62 (0.27%) cases provided an ASC-H result, while 71 (0.31%) were HGSIL. Follow-up cervical dysplasia by colposcopic biopsy and cone biopsy was distributed proportionally between TIS and manual screening for both ASC-H and HGSIL categories. Cervical intraepithelial neoplasia (CIN II/III) was identified on follow-up biopsy of 41% TIS cases and 45% manually screened cases for ASC-H. In the HGSIL subset 71% of TIS cases and 69% manually screened cases showed CIN II/III on follow-up. TIS was 26% less sensitive relative to manual screening for ASC-H cases and 3% less sensitive for HGSIL.

Conclusion:

The similar rate of detection using TIS with an equal percentage of histologic correlation for ASC-H and HGSIL lesions on follow-up histology suggests patients screened by the TIS method are being sent for appropriate follow-up surveillance and treatment. A high-grade or possible high-grade lesion is as likely to be detected by TIS as by a manual screen. The similarities in relative sensitivity and specificity in a direct comparison between manual and TIS screening methodologies indicate that TIS compared to manual screening does not affect detection in patients with high-grade cervical lesions.

Performance of a simple chromatin-rich segmentation algorithm in quantifying basal cell carcinoma from histology images

Background

The use of digital imaging and algorithm-assisted identification of regions of interest is revolutionizing the practice of anatomic pathology. Currently automated methods for extracting the tumour regions in basal cell carcinomas are lacking. In this manuscript a colour-deconvolution based tumour extraction algorithm is presented.

Findings

Haematoxylin and eosin stained basal cell carcinoma histology slides were digitized and analyzed using the open source image analysis program ImageJ. The pixels belonging to tumours were identified by the algorithm, and the performance of the algorithm was evaluated by comparing the pixels identified as malignant with a manually determined dataset.

The algorithm achieved superior results with the nodular tumour subtype. Pre-processing using colour deconvolution resulted in a slight decrease in sensitivity, but a significant increase in specificity. The overall sensitivity and specificity of the algorithm was 91.0% and 86.4% respectively, resulting in a positive predictive value of 63.3% and a negative predictive value of 94.2%

Conclusions

The proposed image analysis algorithm demonstrates the feasibility of automatically extracting tumour regions from digitized basal cell carcinoma histology slides. The proposed algorithm may be adaptable to other stain combinations and tumour types.

Human Papillomavirus and Pap Smear

High-risk human papillomavirus (HPV) infection and viral persistence is a major risk factor in the development of squamous intraepithelial lesions and invasive carcinoma of the cervix. In the United States, deaths due to squamous cell carcinoma of the cervix have fallen by 75% since the 1960s because of Papanicolaou (Pap) smear screening. However, the traditional Pap had a sensitivity of about 70% for detecting clinically significant precancerous lesions and cancer because of sampling and interpretive errors. The introduction of 2 liquid-based Pap smear collection systems in the 1990s, the use of HPV testing as a triage and co-testing with Pap smear, and the introduction of 2 automated screening devices have had a significant impact on improving the detection of such precancerous lesions. This review provides an analysis of the changes in Pap smear collection, improvements in screening, the evolutionary changes of high-risk HPV testing, reporting terminology of Pap smears, and clinical management guidelines. The future impact of 2 prophylactic HPV vaccines on the incidence of cervical carcinoma is also discussed. This article also discusses alternatives such as primary screening for high-risk HPV testing with visual inspection for cervical cancer detection used in resource-poor settings with a high incidence of cervical cancer.

Patients with cervical cancer: why did screening not prevent these cases?

OBJECTIVE

The objective of the study was to assess the screening history of women with cervical cancer and review normal cervical smears 5 years preceding the diagnosis.

STUDY DESIGN

Cytological and histological results of 401 women treated for invasive cervical cancer between 1991 and 2008 at the Radboud University Nijmegen Medical Center were studied. Ninety-eight normal smears were reviewed.

RESULTS

Of the 401 women, 269 (67%) received at least 1 invitation for the national screening program for cervical cancer (NCSP). One- third fell outside the target age of the NCSP. Seventeen percent never responded to the invitation(s). Twenty-one percent had 1 or more normal smears within 5 years preceding the diagnosis. After review, only 39% of those smears were reviewed as a normal smear.

CONCLUSION

Half of the women with cervical cancer were never screened because of the limited target age range or nonattendance. Twenty-one percent had a normal smear within 5 years preceding the diagnosis, caused by interpretation and/or sampling errors.

Implementation of the ThinPrep Imaging System in a tertiary military medical center

BACKGROUND

The ThinPrep Imaging System (TIS) was implemented at Brooke Army Medical Center (BAMC) in February 2006 and has been a crucial part of the ability of the Department of Pathology and Laboratory Services ability to improve efficiency and turnaround times for Papanicolaou (Pap) test reporting. The increased detection rate of squamous abnormalities, specifically high-grade squamous intraepithelial lesions (HSIL), has been well documented by many studies. In addition, the TIS has increased productivity for many laboratories. The objective of this study was to evaluate the effects of implementing the TIS at BAMC, a tertiary military medical center. Specifically, the following were assessed: 1) whether the detection of squamous abnormalities was increased with the TIS, 2) how the rate of high-risk human papillomavirus (HR-HPV) detection in atypical squamous cells (ASC) of undetermined significance (ASC-US) cases changed (or did not change) before and after implementation of the TIS, and 3) how the TIS influenced productivity.

METHODS

All gynecologic cytology at BAMC has been collected and processed using the ThinPrep system since 2002. Before February 2006 and before implementation of the TIS, Pap tests were screened manually by the cytotechnologists. Detection rates of squamous abnormalities were compared between the period from February 2005 to December 2005 (manual screening) and the period from February 2006 to December 2006 (image-assisted screening). Squamous abnormalities included ASC-US; ASC, cannot rule out HSIL (ASC-H); low-grade squamous intraepithelial lesion (LSIL); HSIL; glandular abnormalities; and malignancies (squamous or glandular). In addition, the rates of HR-HPV-positive, HR-HPV-negative, and HR-HPV-quantity not sufficient were compared for the same periods. During both periods, testing for HR-HPV was performed only on ASC-US Pap tests. HR-HPV was tested with Digene Hybrid Capture 2 methodology. Productivity was calculated as the change in average slides screened per hour before and after imager implementation.

RESULTS

In total, 107,647 Pap tests were analyzed in the 2005 (54,438 Pap tests) and 2006 (53,209 Pap tests) timeframes. Increases in the detection of ASC-H, atypical glandular cells (AGC), LSIL, and HSIL were statistically significant. The proportion of negative for intraepithelial lesion or malignancy (NILM) and unsatisfactory cases decreased significantly with implementation of the TIS. The ASC to squamous intraepithelial lesion (ASC:SIL) ratio decreased from 1.5 to 1.0 after TIS implementation. Decreases in the ASC-US HR-HPV-positive proportion and increases in the ASC-US HR-HPV-negative proportion after implementation of the TIS were statistically significant. In our laboratory, a 60% increase in productivity was noted with use of the TIS.

CONCLUSIONS

Implementation of the TIS at BAMC significantly increased the detection of ASC-H, AGC, LSIL, and HSIL but had no significant impact on the ASC-US detection rate. Although the ASC-US rate did not change, both the HR-HPV-positive rate and the ASC:SIL ratio decreased. The data from the current study suggested that, at least initially, the use of imager-directed screening may increase the number of clinically insignificant ASC-US Pap tests.

Digital pathology: a tool for 21st century neuropathology

Digital pathology represents an electronic environment for performing pathologic analysis and managing the information associated with this activity. The technology to create and support digital pathology has largely developed over the last decade. The use of digital pathology tools is essential to adapt and lead in the rapidly changing environment of 21st century neuropathology. The utility of digital pathology has already been demonstrated by pathologists in several areas including consensus reviews, quality assurance (Q/A), tissue microarrays (TMAs), education and proficiency testing. These utilities notwithstanding, interface issues, storage and image formatting all present challenges to the integration of digital pathology into the neuropathology work environment. With continued technologic improvements, as well as the introduction of fluorescent side scanning and multispectral detection, future developments in digital pathology offer the promise of adding powerful analytic tools to the pathology work environment. The integration of digital pathology with biorepositories offers particular promise for neuropathologists engaged in tissue banking. The utilization of these tools will be essential for neuropathologists to continue as leaders in diagnostics, translational research and basic science in the 21st century.

Cervical cancer screening: state of the art

PURPOSE OF REVIEW

The objective of cervical cancer screening is to prevent the occurrence of and death from cervical cancer by detecting and treating high-grade squamous intraepithelial lesions. A significant decline in occurrence and mortality from cervical cancer in developed countries has been associated with the application of organized cervical screening programs. The use of the available local health methods in cervical cancer screening can be adjusted in different countries. This review discusses the recent results in traditional and alternative cervical cancer screening.

RECENT FINDINGS

The current recommendations of both the American Cancer Society and the American College of Obstetricians and Gynecologists concerning clinical practice guidelines for cervical cancer screening are commented upon. New methods and new technology for cervical cancer screening are described. Attributable failure factors in the screening process, particularly in the coverage, are analyzed. A critical assessment of the suitability of local cervical cancer screening resources is discussed.

SUMMARY

Screening is clearly a complex multifactorial process, not a test. Nowadays, with the human papillomavirus vaccine on the horizon, screening is the best strategy for cervical cancer control. Good screening programs, with high coverage, quality control and follow-up included, are the basis of obtaining better results. The Papanicolaou test and its variants are the best methods of cervical cancer screening in high-resource settings. Alternative visual inspection using cervical dyes could be the most useful method in low-resource settings. The challenge for the future may be less of a technical nature and more dependent on local finances and screening policies.

Use of the ThinPrep Imaging System does not alter the frequency of interpreting Papanicolaou tests as atypical squamous cells of undetermined significance

BACKGROUND

Automated screening of Papanicolaou tests (Pap tests) improves the productivity of cytopathology laboratories. The ThinPrep Imaging System (TIS) has been widely adopted primarily for this reason for use on ThinPrep Pap tests (TPPT). However, TIS may also influence the interpretation of Pap tests, leading to changes in the frequency of various interpretive categories. The effect of the TIS on rates of TPPT interpretation as atypical squamous cells of undetermined significance (ASC-US) is of concern because any shift in the frequency of ASC-US will alter the sensitivity and specificity of the Pap test. We have sought to determine whether automated screening of TPPT has altered ASC-US rates in our institution when compared with manual screening (MS) of TPPT.

METHODS

A computerized search for all ASC-US with reflex Human Papillomavirus (HPV) testing over a one-year-period (7/1/06 to 6/30/07) was conducted. Cases included both TPPT screened utilizing TIS and screened manually. HPV test results for both groups were recorded. Pertinent follow-up cervical cytology and histology results were retrieved for the period extending to 11/30/07. Automated screening was in clinical use for 10 months prior to the start of the study.

RESULTS

Automated screening was performed on 23,103 TPPT, of which 977 (4.23%) were interpreted as ASC-US. Over the same period, MS was performed on 45,789 TPPT, of which 1924 (4.20%) were interpreted as ASC-US. Reflex HPV testing was positive for high risk (HR) types in 47.4% of the TIS cases and 50.2% of MS cases. Follow-up cervical dysplasia found by colposcopy was also distributed proportionally between the two groups. Cervical intraepithelial neoplasia (CIN) was found on follow-up biopsy of 20.1% of the TIS cases (5.2% CIN 2/3) and 21.2% of MS cases (5.1% CIN 2/3). None of these differences were statistically significant.

CONCLUSION

Use of the ThinPrep Imaging System did not appreciably change ASC-US rates or follow-up reflex HPV test results in our laboratory. This demonstrates that the benefits of automated screening may be obtained without increasing the rate of referral to colposcopy for ASC-US follow-up.

Very low human papillomavirus DNA prevalence in mature women with negative computer-imaged liquid-based Pap tests

BACKGROUND

The prevalence of high-risk Human Papillomavirus DNA (hrHPV DNA) in women with negative Papanicolaou (Pap) test results provides a measure of residual risk for cervical neoplasia after cytology screening. The purpose of this study was to document the prevalence of hrHPV DNA in several thousand women ages > or =30 years with negative ThinPrep Imaging System (TIS)-imaged Pap test results in a large academic hospital cytology laboratory.

METHODS

All cytology-negative TIS-imaged ThinPrep Pap tests (TPPT) with hrHPV DNA tests that were performed by the United States Food and Drug Administration (FDA)-approved Hybrid Capture 2 (HC2) method from May 1, 2005 to November 20, 2006 were identified and reviewed. Imaged-negative Pap test slides associated with a positive hrHPV DNA test result were rescreened manually. Variation in hrHPV DNA prevalence was assessed for different age and ethnic groups.

RESULTS

Of 8070 imaged cytology-negative TPPT from women ages 11 to 90 years, hrHPV DNA test results were also available. Among 7426 women ages > or =30 years with a cytology-negative, TIS-imaged, Pap test, a significant age-associated decline in hrHPV DNA prevalence was noted, 3.4% in 3050 women ages 30-45 years, 2.4% in 7426 women ages 30-90 years, and 1.8% in 5491 women ages 40-90 years. The hrHPV DNA-positive rate was 2.3% in 6012 imaged cytology-negative white women and 4.1% in 739 imaged cytology-negative black women.

CONCLUSIONS

Very low HC2 hrHPV DNA rates in 7426 women ages > or =30 years with cytology-negative, TIS-imaged, ThinPrep, Pap tests were similar to recently published data from 1 other academic center and lower than rates reported in previous studies on cytology-negative North American or European women screened manually with conventional or liquid-based Pap tests. These data may impact assessments of how best to combine cytology and HPV testing.

Accuracy of ThinPrep Imaging System in detecting low-grade squamous intraepithelial lesions

CONTEXT

The ThinPrep Imaging System (Imager) for cervical cytology is used in many US laboratories, but the ability of the system to identify classic changes of low-grade squamous intraepithelial lesion (LSIL) has not been independently reported.

OBJECTIVE

To evaluate the accuracy of this system in detecting classic LSIL cells.

DESIGN

A total of 114 imaged ThinPrep LSIL cases from April to June 2005 were reviewed to determine whether the most diagnostically relevant cells were present in the 22 fields selected by Imager. Those LSIL specimens from January to June 2005 that were initially screened by the Imager and classified as "negative" in the 22 fields were also reviewed. The average number of classic koilocytes per slide was compared among cases that had koilocytes within 22 fields with cases upgraded during full review.

RESULTS

Twelve (10.5%) of 114 LSIL cases from April to June 2005 did not show diagnostic LSIL cells within the initial 22 fields. Full manual rescreening was performed on 1025 cases from January to June (20.4% of negative cases). Nine cases that were initially negative in the 22 fields were revised to LSIL (2.4% of all 381 LSIL cases reported from January to June 2005). An average of 10 to 11 koilocytes were present in these 2 groups, which was significantly lower than the average of 75 koilocytes in cases in which the 22 Imager-selected fields showed LSIL.

CONCLUSIONS

Although the ThinPrep Imager finds abnormal cells in most LSIL cases, the system may have limitations in detecting koilocytes in the 22 Imager-selected fields. When 10% quality control rescreening is performed as required by federal regulations, full manual rescreening will provide the most accurate results.

Introduction of the Thin Prep Imaging System (TIS): experience in a high volume academic practice

Objective

Since the introduction of the liquid-based ThinPrep testing in 1996, most cytology laboratories across the country have adopted the liquid-based cytology (LBC) for Pap test screening. Subsequent to wide-spread adoption of the ThinPrep Pap test, the ThinPrep Imaging System (TIS) Cytyc Corp, Marlborough, MA was introduced to improve the accuracy and efficiency of screening interpretation. We report our initial experience with the TIS at Magee Women's Hospital. We introduced the TIS in December 2004.

Methods

The imager assisted Pap test results over the first 12 months (December 2004 to December 2005) of implementation were reviewed and analyzed. Our implementation protocol included each cytotechnologist manually prescreening 200 negative slides to gain experience with the imager slides and serve as a quality check for the TIS. We re-screened 3400 slides (200 slides each for 17 cytotechnologists) manually which were initially determined to be negative using the TIS. 104,457 Pap tests were imaged on the TIS. 95,899 manually screened Pap tests, 12 months prior to the introduction of the TIS (December 2003–November 2004) are taken as the historic control group for our study.

Results

The mean ASC-US rate employing the automated imager was 8.70% [9088/104,457]. The mean LSIL detection rate was 4.22% [4409/104,457]. The imager did not miss any detectible high-grade lesions during these months, with a HSIL (+) detection rate of 0.68% in comparison to 0.60% by manual screening confirmed by follow-up biopsies. The difference is statistically significant with a p value of 0.022. The definition of false negative rate for purposes of this study is calculated as the number of false negative cases identified out of number of negatives re-screened. The TIS false negative rate was estimated at 0.012% [4/3400].

Conclusion

The overall performance of the TIS in our lab appears to be highly satisfactory in terms of improving sensitivity in screening cervical precursor lesions. The increased accuracy of detection of HSIL indicates a positive impact of the TIS in our laboratory.

Implementation of the ThinPrep® imaging system in a high-volume metropolitan laboratory

The Papanicolaou test has proven to be the most effective cancer screening test ever developed. However, with a declining number of skilled cytotechnologists, there is an increased need for computer assistance in cervical cancer screening. The ThinPrep Imaging System (Cytyc Corporation, Marlborough, MA) is a unique system that combines computer imaging technology and human interpretive expertise in the review of ThinPrep Pap test slides. The purpose of this study is to report on the introduction and validation of this technology and present data related to the performance and productivity in our laboratory. Following completion of the ThinPrep Imaging System validation protocol, all imaged ThinPrep Pap test results were tracked and compared with year-2003 manually screened results to identify whether the Imaging System was effective in aiding human interpretive skills. Cases rescreened in the 10% random quality control (QC) program from the negative population that showed abnormal cells consistent with low-grade squamous intraepithelial lesion (LSIL) and above were compared with imaged versus non-imaged cases to establish an estimated laboratory false-negative (F/N) rate. The study compared results of 82,063 manually screened ThinPrep Pap tests in 2003 with 84,473 imaged ThinPrep Pap tests in 2004. Results demonstrated a significant increase in LSIL (37%) and high-grade squamous intraepithelial lesion (HSIL) (42%) detection on the Imager cohort. The F/N rate was reduced by half. The evaluation period after validation of the Imager showed a significant increase in LSIL and HSIL detection with the ThinPrep Imaging System compared to manual screening. These results demonstrate that the Imager has the potential to allow the cytotechnologists to detect more disease and reduce the false-negative rate for the laboratory. Although not evaluated in this study, cytotechnologists reported increased job satisfaction.

Automated screening versus manual screening: A comparison of the ThinPrep® imaging system and manual screening in a time study

The ThinPrep Imaging System (TIS) is an automated system that assists cytotechnologists in the primary screening of ThinPrep liquid based cervical samples. Between June 1, 2004, and April 1, 2005, four experienced cytotechnologists participated in the study in which the duration of the screening procedure was timed for each of the 11,354 slides included. In every slide 22 fields of view were reviewed, and the samples that contained potentially abnormal cells were fully screened. The screening time was reduced by 42% (mean) (p < 0.001). By manual rescreening of the negative TIS samples, abnormal cells were found in 10 samples (false negative rate 0.14%). In every case the abnormal cells had been identified by the scanner, but misinterpreted by the cytotechnologist. These findings stressed the importance of carefulness in the interpretation of the marked fields and beyond that helped the cytotechnologists and pathologists to have more confidence in the automated system.