Whole-Slide Imaging of Pap Cellblock Preparations Is a Potentially Valid Screening Method

Architectural aspects of cell-blocks as small biopsies

Cell-block preparations have become an essential part of integrated cytology diagnosis. They are essentially microbiopsies that are formalin fixed and embedded in paraffin. This has become more prevalent with greater sample procurement due to the advent of newer biopsy techniques and needles. Cell-blocks allow retrieval of small tissue fragments from cytology specimens that sometimes cannot be processed by alternate cytologic techniques. They represent concentrated, cell-enriched preparations that provide cytologists with the opportunity to evaluate cellular architecture, as well as to perform ancillary testing. A cell-block compatible sample may thus obviate the need for a more invasive procedure such as a tissue biopsy. Microscopic examination of cell-blocks is quick, avoids obscuring material, permits cells to be evaluated in one focal plane, and allows the histologic architecture such as glandular differentiation, papillary formations, and sometimes invasion to be easily identified. This new era of “cytohistology” accordingly requires practicing cytologists to become more familiar with histopathology. This review article discusses the benefit of various architectural patterns identifiable in cell-blocks employed as an adjunct to Pap tests, exfoliative fluid specimens, and fine-needle aspirations.

The utility of cell blocks for international cytopathology teleconsultation by whole slide imaging

INTRODUCTION

Telecytology for second opinion consultation has largely been limited by technical issues, such as the inability to focus well on cellular material. Nevertheless, international telecytology consultation was undertaken at our institution with partners in China and Italy. To overcome issues with scanning cytology slides, we adopted a cell-block (CB) preference for teleconsultation.

METHODS

Telecytology consultation cases received over a 7.5-year period were retrospectively reviewed. Cytology glass slides were scanned without Z-stacking using different whole slide scanners. For one referring site, only haematoxylin-eosin-stained CBs were scanned, as well as immunostains requested by consultants. For another host centre, aspirate smears were also scanned in some cases.

RESULTS

A total of 51 non-gynaecological cases (44 CB only) were evaluated from 48 patients. The specimens included pleural fluids (19), pancreas (14), lymph nodes (6), peritoneal fluids (2) and miscellaneous samples (10). The cytological diagnoses spectrum included 16 (31.37%) cases positive for malignancy, 7 (13.72%) positive for neoplasm, 6 (11.76%) suspicious for malignancy, 10 (19.60%) atypical, 10 (19.60%) negative for malignancy and 2 (3.92%) non-diagnostic. In 42 (82.35%) cases, immunocytochemistry was requested. Turn-around-time ranged from 1.5 to 306 hours.

CONCLUSIONS

Our experience shows that international telecytology for consultation purposes involving non-gynaecological cases is feasible. A second opinion interpretation was rendered in the majority (64.7%) of cases. Utilising CB only for cytology consultations by whole slide imaging solved focus issues that typically plague evaluation of cytology aspirate smears.

Diagnostic Validation of a Whole-Slide Imaging Scanner in Cytological Samples: Diagnostic Accuracy and Comparison With Light Microscopy

Digital slides created by whole-slide imaging scanners can be evaluated by pathologists located in remote sites, but the process must be validated before this technology can be applied to routine cytological diagnosis. The aim of this study was to validate a whole-slide imaging scanner for cytological samples. Sixty cytological samples, whose diagnoses were confirmed by gold-standard examinations (histology or flow cytometry), were digitalized using a whole-slide imaging scanner. Digital slides and glass slides were examined by 3 observers with different levels of cytopathological expertise. No significant differences were noted between digital and glass slides in regard to the number of cases correctly diagnosed, or the sensitivity, specificity, or diagnostic accuracy, irrespective of the observers’ expertise. The agreements between the digital slides and the gold-standard examinations were moderate to substantial, while the agreements between the glass slides and the gold-standard examinations were substantial for all 3 observers. The intraobserver agreements between digital and glass slides were substantial to almost perfect. The interobserver agreements when evaluating digital slides were moderate between observers 1 and 2 and between observers 1 and 3 while they were substantial between observers 2 and 3. In conclusion, our study demonstrated that the digital slides produced by the whole-slide imaging scanner are adequate to diagnose cytological samples and are similar among clinical pathologists with differing levels of expertise.

Constant Quest for Quality: Digital Cytopathology

Background:

Special consideration should be given when creating and selecting cytopathology specimens for digitization to maximize quality. Advances in scanning and viewing technology can also improve whole-slide imaging (WSI) output quality.

Methods:

Accumulated laboratory experience with digitization of glass cytopathology slides was collected.

Results:

This paper describes characteristics of a cytopathology glass slide that can reduce quality on resulting WSI. Important points in the glass cytopathology slide selection process, preparation, scanning, and WSI-editing process that will maximize the quality of the resulting acquired digital image are covered. The paper outlines scanning solutions which have potential to predict issues with a glass cytopathology slide before image acquisition, allowing for adjustment of the scanning approach. WSI viewing solutions that better simulate the traditional microscope experience are also discussed.

Conclusion:

In addition to taking advantage of technical advances, practical steps can taken to maximize quality of cytopathology WSI.

Development of Whole Slide Imaging on Smartphones and Evaluation With ThinPrep Cytology Test Samples: Follow-Up Study

Background

The smartphone-based whole slide imaging (WSI) system represents a low-cost and effective alternative to automatic scanners for telepathology. In a previous study, the development of one such solution, named scalable whole slide imaging (sWSI), was presented and analyzed. A clinical evaluation of its iOS version with 100 frozen section samples verified the diagnosis-readiness of the produced virtual slides.

Objective

The first aim of this study was to delve into the quantifying issues encountered in the development of an Android version. It should also provide insights into future high-resolution real-time feedback medical imaging apps on Android and invoke the awareness of smartphone manufacturers for collaboration. The second aim of this study was to further verify the clinical value of sWSI with cytology samples. This type is different from the frozen section samples in that they require finer detail on the cellular level.

Methods

During sWSI development on Android, it was discovered that many models do not support uncompressed camera pixel data with sufficient resolution and full field of view. The proportion of models supporting the optimal format was estimated in a test on 200 mainstream Android models. Other factors, including slower processing speed and camera preview freezing, also led to inferior performance of sWSI on Android compared with the iOS version. The processing speed was mostly determined by the central processing unit frequency in theory, and the relationship was investigated in the 200-model simulation experiment with physical devices. The camera preview freezing was caused by the lag between triggering photo capture and resuming preview. In the clinical evaluation, 100 ThinPrep cytology test samples covering 6 diseases were scanned with sWSI and compared against the ground truth of optical microscopy.

Results

Among the tested Android models, only 3.0% (6/200) provided an optimal data format, meeting all criteria of quality and efficiency. The image-processing speed demonstrated a positive relationship with the central processing unit frequency but to a smaller degree than expected and was highly model-dependent. The virtual slides produced by sWSI on Android and iOS of ThinPrep cytology test samples achieved similar high quality. Using optical microscopy as the ground truth, pathologists made a correct diagnosis on 87.5% (175/200) of the cases with sWSI virtual slides. Depending on the sWSI version and the pathologist in charge, the kappa value varied between .70 and .82. All participating pathologists considered the quality of the sWSI virtual slides in the experiment to be adequate for routine usage.

Conclusions

Limited by hardware and operating system support, the performance of sWSI on mainstream Android smartphones did not fully match the iOS version. However, in practice, this difference was not significant, and both were adequate for digitizing most of the sample types for telepathology consultation.

Clinical Applications of Whole-slide Imaging in Anatomic Pathology

The development of whole-slide imaging has paved the way for digitizing of glass slides that are the basis for surgical pathology. This transformative technology has changed the landscape in research applications and education but despite its tremendous potential, its adoption for clinical use has been slow. We review the various niche applications that initiated awareness of this technology, provide examples of clinical use cases, and discuss the requirements and challenges for full adoption in clinical diagnosis. The opportunities for applications of image analysis tools in a workflow will be changed by integration of whole-slide imaging into routine diagnosis.

The utility of pap cell block preparations with liqui-PREP™ cell pellets to clarify the cytological diagnosis of atypical squamous cells of undetermined significance and atypical glandular cells

OBJECTIVE

Atypical squamous cells of undetermined significance (ASCUS) and atypical glandular cells (AGC) reflect cellular abnormalities insufficient for clear diagnosis. We used cell pellets obtained from liquid-based cytology (LBC) to prepare cell blocks (CB) and clarify the initial diagnosis of ASCUS and AGC.

STUDY DESIGN

A total of 393 CBs with initial diagnosis of ASCUS or AGC were processed. Of those, 305 of the ASCUS and 20 of the AGC had adequate specimens. We compared results of CBs prepared from ASCUS and AGC to determine which had higher frequencies of higher-grade lesions.

RESULTS

A majority of specimens (83%) were adequate for evaluation. Compared with the initial diagnosis, 14% (42/305) of ASCUS were diagnosed with low-grade squamous intraepithelial lesion (LSIL) in CB, while 10% (2/20) of AGC were diagnosed with LSIL or adenocarcinoma. No statistical relationship between the initial diagnosis of ASCUS and AGC and results of higher-grade lesions in CB is evident as determined by p value greater than 0.05 (p = 0.228).

CONCLUSIONS

CBs prepared from Liqui-PREP cell pellets are, in most cases, assessable and can be useful as an adjunctive test to help clarify the initial diagnosis of ASCUS and AGC. Diagn. Cytopathol. 2017;45:520-525. © 2017 Wiley Periodicals, Inc.

The State of Cell Blocks and Ancillary Testing: Past, Present, and Future

Cell blocks are an integral part of cytology, but their utility is recognized probably more now than ever before, largely owing to the significant role they play in ancillary testing, particularly molecular diagnostics. Modifications to improve the cell block method initially introduced more than a century ago have been made over the years. Though their value is acknowledged and they are widely used across laboratories, cell block preparations are not standardized and results of ancillary testing performed on them are inconsistent. This article reviews the state of cell blocks-summarizes the more common, currently available and used methods and their corresponding advantages and shortcomings, outlines the role of alternative techniques (eg, smears), and proposes methods to optimize results.

Cell Block Preparation versus Liquid-Based Thin-Layer Cervical Cytology: A Comparative Study Evaluating Human Papillomavirus Testing by Hybrid Capture-2/Cervista, in situ Hybridization and p16 Immunohistochemistry

OBJECTIVE

Cell block (CB) preparations from residual liquid-based Pap samples have been shown to be of diagnostic value. In this study we evaluated human papillomavirus (HPV) in situ hybridization (ISH) and p16 immunohistochemistry (IHC) on CB preparations and compared the results with the primary diagnosis and standard HPV tests.

DESIGN

In total, 197 HE-stained CB slides prepared from CBs from residual Pap samples (152 ASCUS, 2 ASC-H, 32 LGSIL, 4 HGSIL, 1 AGUS and 6 normal) were analyzed. Hybrid Capture-2 (HC-2)/Cervista testing and HPV ISH and p16 IHC were performed on the CB samples. The test performance characteristics were compared with HPV and p16 assay performances.

RESULTS

The cellular architecture was well maintained in CBs with excellent consistency. HPV ISH testing had an excellent concordance with the HC-2/Cervista methods (85%) with high sensitivity (82.6%; 95% CI 75.9, 89.4) and specificity (89.3%). Of all the p16 tests, 38% were positive (60 out of 159 samples). The overall concordance between p16 and HC-2/Cervista (64%), or between p16 and ISH (68%), was lower than the concordance between ISH and HC-2/Cervista (85%).

CONCLUSIONS

HPV ISH and p16 IHC testing is feasible, cost effective and practical. A combination of the two tests would ultimately improve diagnostic accuracy, leading to better therapeutic decisions.