Reliability of telepathology for frozen section service

Intraoperative assessment of axillary sentinel lymph nodes by telepathology

PURPOSE

Although axillary dissection is no longer indicated for many breast cancer patients with 1-2 positive axillary sentinel lymph nodes (ASLN), intraoperative ASLN assessment is still performed in many institutions for patients undergoing mastectomy or neoadjuvant therapy. With recent advancements in digital pathology, pathologists increasingly evaluate ASLN via remote telepathology. We aimed to compare the performance characteristics of remote telepathology and conventional on-site intraoperative ASLN assessment.

METHODS

Data from ASLN evaluation for breast cancer patients performed at two sites between April 2021 and October 2022 was collated. Remote telepathology consultation was conducted via the Aperio eSlideManager system.

RESULTS

A total of 385 patients were identified during the study period (83 telepathology, 302 on-site evaluations). Although not statistically significant (P = 0.20), the overall discrepancy rate between intraoperative and final diagnoses was slightly higher at 9.6% (8/83) for telepathology compared with 5.3% (16/302) for on-site assessment. Further comparison of performance characteristics of ASLN assessment between telepathology and conventional on-site evaluation revealed no statistically significant differences between deferral rates, discrepancy rates, interpretive or sampling errors, major or minor disagreements, false negative or false positive results as well as clinical impact and turn-around time (P ≥ 0.12).

CONCLUSION

ASLN assessment via telepathology is not significantly different from conventional on-site evaluation, although it shows a slightly higher overall discrepancy rate between intraoperative and final diagnoses (9.6% vs. 5.3%). Further studies are warranted to ensure accuracy of ASLN assessment via telepathology.

[Remote intraoperative frozen section diagnosis in pathology with high definition video transmission through YouTube and Twitch]

INTRODUCTION

Remote diagnosis of frozen sections is an important asset for hospitals that do not have full-time pathologists. Ongoing advances in information technology are constantly being incorporated and we have used real time high-definition video.

MATERIAL AND METHODS

Our microscope was connected to a video camera with a 1080p resolution and its signal sent to the computer where OBS software encoded and transmitted video streams to YouTube and Twitch distribution platforms.

RESULTS

The high-quality image thus achieved allows an accurate, remote evaluation of frozen sections. Access through web pages allows them to be reviewed anywhere from any device with an Internet connection.

DISCUSSION

Remote intraoperative diagnosis is a challenge for pathologists and image quality is a critical requirement for its implementation, which can be solved by video streaming technology. The proper training of technicians is essential. This system can also be applied to many other areas of pathology, such as teaching and consultation.

Four-Year Experience of Digital Slide Telepathology for Intraoperative Frozen Section Consultations in a Two-Site French Academic Department of Pathology

OBJECTIVES

To share our experience with digital slide telepathology for intraoperative frozen section consultations (IOCs) and to describe its evolution over time by reporting performance metrics and addressing organizational and economic aspects.

METHODS

Since 2013, a technician has been alone at the surgical site. At the other site, the pathologist opens the digital slide from a local server via the intranet. Three periods were compared: a 6-month period of conventional IOC (period 1), a 24-month period of telepathology at 6 months after implementation (period 2), and a 12-month period of telepathology at 3.5 years after implementation (period 3).

RESULTS

In total, 87 conventional IOCs and 464 and 313 IOCs on digital slides were performed respectively during periods 1, 2, and 3; mean turnaround time was 27, 36, and 38 minutes, respectively, and there were a mean number of 1.1, 1.1, and 1.3 slides, respectively, per IOC. Diagnostic accuracy was achieved in 95.4%, 92.7%, and 93.9%, respectively, of IOCs (not significant). The additional cost is in the same range as the cost of urgent transport by courier.

CONCLUSIONS

Developing IOC with digital slides is a challenge but is necessary to optimize medical time in the current context of pathologist shortage and budget restrictions.

The Next Generation Robotic Microscopy for Intraoperative Teleneuropathology Consultation

Introduction

Teleneuropathology at our institution evolved over the last 17 years from using static to dynamic robotic microscopy. Historically (2003-2007), using older technology, the deferral rate was 19.7%, and the concordance was 81% with the final diagnosis. Two years ago, we switched to use hybrid robotic devices to perform these intraoperative (IO) consultations because our older devices were obsolete. The aim of this study was to evaluate the impact this change had on our deferral and concordance rates with teleneuropathology using this newer instrument.

Materials and Methods

Aperio LV1 4-slide capacity hybrid robotic scanners with an attached desktop console (Leica Biosystems, Vista, CA, USA) and GoToAssist (v4.5.0.1620, Boston, MA, USA) were used for IO telepathology cases. A cross-sectional comparative study was conducted comparing teleneuropathology from three remote hospitals (193 cases) to IO neuropathology consultation performed by conventional glass slide examination at a light microscope (310 cases) from the host hospital. Deferral and concordance rates were compared to final histopathological diagnoses.

Results

The deferral rate for IO teleneuropathology was 26% and conventional glass slide 24.24% (P = 0.58). The concordance rate for teleneuropathology was 93.94%, which was slightly higher than 89.09% for conventional glass slides (P = 0.047).

Conclusion

The new hybrid robotic device for performing IO teleneuropathology interpretations at our institution was as effective as conventional glass slide interpretation. While we did observe a noticeable change in the deferral rate compared to prior years, we did appreciate the marked improvement of the concordance rate using this new hybrid scanner.

Systematic Review of the Use of Telepathology During Intraoperative Consultation

OBJECTIVE

To compare studies that used telepathology systems vs conventional microscopy for intraoperative consultation (frozen-section) diagnosis.

METHODS

A total of 56 telepathology studies with 13,996 cases in aggregate were identified through database searches.

RESULTS

The concordance of telepathology with the reference standard was generally excellent, with a weighted mean of 96.9%. In comparison, we identified seven studies using conventional intraoperative consultation that showed a weighted mean concordance of 98.3%. Evaluation of the risk of bias showed that most of these studies were low risk.

CONCLUSIONS

Despite limitations such as variation in reporting and publication bias, this systematic review provides strong support for the safety of using telepathology for intraoperative consultations.

Experience with telepathology in combination with diagnostic assistance systems in countries with restricted resources

INTRODUCTION

We describe the use of telepathology in countries with restricted resources using two diagnosis assistance systems (Isabel and Memem7) in addition to the diagnoses made by experts in pathology via the iPath-Network.

METHODS

A total of 156 cases, largely from Afghanistan, were analysed; 18 cases had to be excluded because of poor image quality.

RESULTS

Of the remaining 138 cases (100%), a responsible physician provided a tentative diagnosis for 61.6% of them. With a diagnosis from a consultant pathologist, it was then possible to make a definite diagnosis in 84.8% of cases on the basis of images taken from hematoxylin and eosin staining sections alone. The use of the diagnosis assistance systems resulted in an ordered list of differential diagnoses in 82.6% (IsabelHealth) and in 74.6% (Memem7) of cases, respectively. Adding morphological terminology reduced the list of possible diagnoses to 52.2% (72 cases, Memem7), but improved their quality.

DISCUSSION

In summary, diagnosis assistance systems are promising approaches to provide physicians in countries with restricted resources with lists of probable differential diagnoses, thus increasing the plausibility of the diagnosis of the consultant pathologist.

Parathyroid Frozen Section Interpretation via Desktop Telepathology Systems: A Validation Study

Background

Telepathology can potentially be utilized as an alternative to having on-site pathology services for rural and regional hospitals. The goal of the study was to validate two small-footprint desktop telepathology systems for remote parathyroid frozen sections.

Subjects and Methods

Three pathologists retrospectively diagnosed 76 parathyroidectomy frozen sections of 52 patients from three pathology services in Australia using the "live-view mode" of MikroScan D2 and Aperio LV1 and in-house direct microscopy. The final paraffin section diagnosis served as the "gold standard" for accuracy evaluation. Concordance rates of the telepathology systems with direct microscopy, inter-pathologist and intra-pathologist agreement, and the time taken to report each slide were analyzed.

Results

Both telepathology systems showed high diagnostic accuracy (>99%) and high concordance (>99%) with direct microscopy. High inter-pathologist agreement for telepathology systems was demonstrated by overall kappa values of 0.92 for Aperio LV1 and 0.85 for MikroScan D2. High kappa values (from 0.85 to 1) for intra-pathologist agreement within the three systems were also observed. The time taken per slide by Aperio LV1 and MicroScan D2 within three pathologists was about 3.0 times (P < 0.001, 95% confidence interval [CI]: 2.8-3.2) and 7.7 times (P < 0.001, 95% CI: 7.1-8.3) as long as direct microscopy, respectively, while MikroScan D2 took about 2.6 times as long as Aperio LV1 (P < 0.001, 95% CI: 2.4-2.7). All pathologists evaluated Aperio LV1 as being more user-friendly.

Conclusions

Telepathology diagnosis of parathyroidectomy frozen sections through small-footprint desktop systems is accurate, reliable, and comparable with in-house direct microscopy. Telepathology systems take longer than direct microscopy; however, the time taken is within clinically acceptable limits. Aperio LV1 takes shorter time than MikroScan D2 and is more user-friendly.

Review of the use of telepathology for intraoperative consultation

INTRODUCTION

The use of telepathology in intraoperative consultations has been increasing due to limited time and availability of pathologists, and the demand for increased access to pathology subspecialists in difficult cases. The five main categories of telepathology are (1) static, (2) dynamic, (3) robotic, (4) whole slide imaging (WSI), and (5) hybrid methods. The majority of these methods have been found to offer diagnostic accuracy rates similar to conventional microscopy, at the cost of slightly prolonged time to evaluate slides.

AREAS COVERED

Herein we discuss the salient features of each telepathology method and provide examples of their performance reported in the literature.

EXPERT COMMENTARY

Telepathology systems from any of the aforementioned categories can be employed to achieve timely and accurate diagnoses as long as they meet clinical needs and are validated for the intended use case. The decision to purchase a particular system depends on the clinical application, specific needs and budget of the laboratory, as well as the personal preference of the telepathologists involved. The adoption of telepathology practice is likely to expand in order to meet the increasing demand for subspecialist consultation and as technology advances to improve diagnostic accuracy and workflow.

Frozen section evaluation via dynamic real-time nonrobotic telepathology system in a university cancer center by resident/faculty cooperation team

Frozen section telepathology interpretation experience has been largely limited to practices with locations significantly distant from one another with sporadic need for frozen section diagnosis. In 2010, we established a real-time nonrobotic telepathology system in a very active cancer center for daily frozen section service. Herein, we evaluate its accuracy compared to direct microscopic interpretation performed in the main hospital by the same faculty and its cost-efficiency over a 1-year period. From 643 (1,416 parts) cases requiring intraoperative consultation, 333 cases (690 parts) were examined by telepathology and 310 cases (726 parts) by direct microscopy. Corresponding discrepancy rates were 2.6% (18 cases: 6 [0.9%] sampling and 12 [1.7%] diagnostic errors) and 3.2% (23 cases: 8 [1.1%] sampling and 15 [2.1%] diagnostic errors), P = .63. The sensitivity and specificity of intraoperative frozen diagnosis were 0.92 and 0.99, respectively, in telepathology and 0.90 and 0.99, respectively, in direct microscopy. There was no correlation of error incidence with postgraduate year level of residents involved in the telepathology service. Cost analysis indicated that the time saved by telepathology was $19,691.00 over 1 year of the study period, whereas the capital cost for establishing the system was $8,924.00. Thus, real-time nonrobotic telepathology is a reliable and easy-to-use tool for frozen section evaluation in busy clinical settings, especially when frozen section service involves more than one hospital, and it is cost-efficient when travel is a component of the service.

Utility of telepathology as a consultation tool between an off-site surgical pathology suite and affiliated hospitals in the frozen section diagnosis of lung neoplasms

Background:

Increasingly, as in our institution, operating rooms are located in hospitals and the pathology suite is located at a distant location because of off-site consolidation of pathology services. Telepathology is a technology which bridges the gap between pathologists and offers a means to obtain a consultation remotely. We aimed to evaluate the utility of telepathology as a means to assist the pathologist at the time of intraoperative consultation of lung nodules when a subspecialty pathologist is not available to directly review the slide.

Methods:

Cases of lung nodules suspicious for a neoplasm were included. Frozen sections were prepared in the usual manner. The pathologists on the intraoperative consultation service at two of our system hospitals notified the thoracic pathologist of each case after rendering a preliminary diagnosis. The consultation was performed utilizing a Nikon™ Digital Sight camera and web-based Remote Medical Technologies™ software with live video streaming directed by the host pathologist. The thoracic pathologist rendered a diagnosis without knowledge of the preliminary interpretation then discussed the interpretation with the frozen section pathologist. The interpretations were compared with the final diagnosis rendered after sign-out.

Results:

One hundred and three consecutive cases were included. The frozen section pathologist and a thoracic pathologist had concordant diagnoses in 93 cases (90.2%), discordant diagnoses in nine cases (8.7%), and one case in which both deferred. There was an agreement between the thoracic pathologist's diagnosis and the final diagnosis in 98% of total cases including 8/9 (88.9%) of the total discordant cases. In two cases, if the thoracic pathologist had not been consulted, the patient would have been undertreated.

Conclusions:

We have shown that telepathology is an excellent consultation tool in the frozen section diagnosis of lung nodules.

Whole slide imaging: uses and limitations for surgical pathology and teaching

Advances in computer and software technology and in the quality of images produced by digital cameras together with development of robotic devices that can take glass histology slides from a cassette holding many slides and place them in a conventional microscope for electronic scanning have facilitated the development of whole slide imaging (WSI) systems during the past decade. Anatomic pathologists now have opportunities to test the utility of WSI systems for diagnostic, teaching and research purposes and to determine their limitations. Uses include rendering primary diagnoses from scanned hematoxylin and eosin stained tissues on slides, reviewing frozen section or routine slides from remote locations for interpretation or consultation. Also, WSI can replace physical storage of glass slides with digital images, storing images of slides from outside institutions, presenting slides at clinical or research conferences, teaching residents and medical students, and storing fluorescence images without fading or quenching of the fluorescence signal. Limitations include the high costs of the scanners, maintenance contracts and IT support, storage of digital files and pathologists' lack of familiarity with the technology. Costs are falling as more devices and systems are sold and cloud storage costs drop. Pathologist familiarity with the technology will grow as more institutions purchase WSI systems. The technology holds great promise for the future of anatomic pathology.

Overview of Telepathology

Telepathology is the practice of remote pathology using telecommunication links to enable the electronic transmission of digital pathology images. Telepathology can be used for remotely rendering primary diagnoses, second opinion consultations, quality assurance, education, and research purposes. The use of telepathology for clinical patient care has been limited mostly to large academic institutions. Barriers that have limited its widespread use include prohibitive costs, legal and regulatory issues, technologic drawbacks, resistance from pathologists, and above all a lack of universal standards. This article provides an overview of telepathology technology and applications.

Virtual surgical pathology in underdeveloped countries: The Zambia Project

Only 1 surgical pathology laboratory is available in Zambia, a country with a population of 12 million people. Since 2004 the Italian association of pathologists Patologi Oltre Frontiera has been working to create a virtual laboratory through the use of telemedicine. The project has involved staining histologic preparations on site, with the interpretation of imaged slides performed abroad through telepathology. Starting in April 2007, all surgical specimens obtained in Mtendere Mission Hospital, Chirundu, Zambia, were submitted for microscopic examination through whole-slide scans. Two independent Italian pathologists evaluated the cases by means of satellite connection and the final diagnoses were sent to Zambian clinicians via the internet. This article describes the spectrum of diagnoses made via telepathology for the Zambian population. Also, we analyze the concordant and discordant data between this telepathology method and traditional microscopy in a developing country. Moreover, we provide possible solutions for providing pathology services in other underdeveloped countries.

Implementation of telepathology in the republic of georgia

Telepathology in the Republic of Georgia is still evolving. Although much progress has been made around the world, especially in the field of digital imaging and virtual slides, telepathology in Georgia still revolves around static telepathology. The results of the NATO Networking Infrastructure Grant "ePathology-Virtual Pathology Center in Georgia as the continuation of Virtual Health Care Center" are presented. It is a practical implementation of telepathology in Georgia as a best practice example. Using basic methodology: idea-analysis-conception-implementation-test/deployment, the ePathology server was created for the establishment of telepathology in Georgia. Two main services were made available on the server: Simple Machines Forum (eConsultation) and Moodle (eLearning) under the premise "keep it small, safe, and simple." The ePathology server works well. By its application, introduction of the Pap-smear technique and 2001 Bethesda System for reporting cervicovaginal cytologic diagnosis has been done. The application of easily available and adaptable technology, together with the improvement of the infrastructure conditions, is the essential basis for telemedical applications. Telepathology is a very useful and applicable tool for consulting on difficult pathology cases. It has significantly increased knowledge exchange and thereby ensured a better medical service.

Comparison of telepathology systems in neuropathological intraoperative consultations

Telepathology has emerged in recent years as a viable solution for providing rapid expert subspecialty consultations to geographically dispersed sites. The Neuropathology Division at the University of Pittsburgh Medical Center has utilized telepathology systems for the past 7 years to perform intraoperative consultations for neurosurgeons at a separate hospital. In 2007 the division switched to a next-generation dynamic robotic system with additional features, including higher resolution, faster image transmission speed, fine-focus control using the mouse fingerwheel, and multiple slide holding capacity. The diagnostic outcomes from a total of 262 intraoperative consultations performed using this new system are compared with 159 consultations using the prior system in 2006 and with outcomes from over 900 conventional consultations from 2006-2008. These results show that telepathology can be used to diagnose challenging tumors, and that differences in outcomes are as much a function of the different surgeries performed at different sites as is the diagnostic modality used.

Frozen-section diagnosis by wireless telepathology and ultra portable computer: use in pathology resident/faculty consultation

Residents in anatomic pathology are allowed increased diagnostic responsibility including the initial interpretation of intraoperative frozen-section consultations during their years of training. This frozen-section responsibility requires staff faculty backup for diagnostic confirmation and consultation. In this study, we tested a telepathology system using an ultra portable computer with a 4.5-in diagonal screen (scrolled image size of 2.5 x 1.75 in, width x height) and both wireless Local Area Network (LAN) final connection from a DSL and wireless Wide Area Network (WAN) telecommunications. The diagnostic agreement for a chief resident/faculty staff duo using telepathology for 100 consecutive frozen-section cases (50 with wireless LAN final connection and 50 with wireless WAN) with limited clinical information was compared with the original frozen-section diagnosis rendered by other staff pathologists. There was diagnostic agreement for 95 of the 100 cases. For the 5 that were discordant, 2 were deemed to be errors in the original frozen-section diagnosis; 1 was not clinically important; and 2 were believed to have potential clinical implications. For the 2 having potential clinical importance, the absence of knowledge of the gross findings in each case and the preoperative biopsy results for one specimen contributed to the misinterpretation of the frozen sections. The median time between transmission of image(s) from the chief resident to the faculty consultant until diagnosis by the latter was 1 minute 42 seconds for wireless WAN and 51 seconds for the wireless LAN final connection to the display device. We conclude that a telepathology system using an ultra portable computer and wireless telecommunications is useful for frozen-section consultation between an experienced resident and a faculty member in pathology.

Clinical Application of Dynamic Telepathology in Mohs Surgery

BACKGROUND

Telepathology is an expanding technology in multiple fields for remote pathology diagnosis and consultation. The use of telepathology in Mohs surgery has been very limited.

OBJECTIVE

To describe the clinical experience of using a telepathology system for intraoperative consultations on difficult frozen sections during Mohs surgery.

MATERIALS AND METHODS

Intraoperative consultation with a dermatopathologist was obtained using a dynamic telepathology system for all questions arising on frozen sections during Mohs surgery for nonmelanoma skin cancers during a 2-year period.

RESULTS

The most common reason for consultation was to distinguish basal cell carcinoma from a benign histologic simulant on Mohs frozen sections. Other uses included determining tumor histology and distinguishing inflammation from residual tumor.

CONCLUSION

Dynamic telepathology is a useful and convenient adjunct in the Mohs surgery practice for intraoperative consultations on difficult frozen sections.

An array microscope for ultrarapid virtual slide processing and telepathology. Design, fabrication, and validation study

This paper describes the design and fabrication of a novel array microscope for the first ultrarapid virtual slide processor (DMetrix DX-40 digital slide scanner). The array microscope optics consists of a stack of three 80-element 10 x 8-lenslet arrays, constituting a "lenslet array ensemble." The lenslet array ensemble is positioned over a glass slide. Uniquely shaped lenses in each of the lenslet arrays, arranged perpendicular to the glass slide constitute a single "miniaturized microscope." A high-pixel-density image sensor is attached to the top of the lenslet array ensemble. In operation, the lenslet array ensemble is transported by a motorized mechanism relative to the long axis of a glass slide. Each of the 80 miniaturized microscopes has a lateral field of view of 250 microns. The microscopes of each row of the array are offset from the microscopes in other rows. Scanning a glass slide with the array microscope produces seamless two-dimensional image data of the entire slide, that is, a virtual slide. The optical system has a numerical aperture of N.A.= 0.65, scans slides at a rate of 3 mm per second, and accrues up to 3,000 images per second from each of the 80 miniaturized microscopes. In the ultrarapid virtual slide processing cycle, the time for image acquisition takes 58 seconds for a 2.25 cm2 tissue section. An automatic slide loader enables the scanner to process up to 40 slides per hour without operator intervention. Slide scanning and image processing are done concurrently so that post-scan processing is eliminated. A virtual slide can be viewed over the Internet immediately after the scanning is complete. A validation study compared the diagnostic accuracy of pathologist case readers using array microscopy (with images viewed as virtual slides) and conventional light microscopy. Four senior pathologists diagnosed 30 breast surgical pathology cases each using both imaging modes, but on separate occasions. Of 120 case reads by array microscopy, there were 3 incorrect diagnoses, all of which were made on difficult cases with equivocal diagnoses by light microscopy. There was a strong correlation between array microscopy vs. "truth" diagnoses based on surgical pathology reports. The kappa statistic for the array microscopy vs. truth was 0.96, which is highly significant (z=10.33, p <0.001). There was no statistically significant difference between rates of agreement with truth between array microscopy and light microscopy (z=0.134, p >0.05). Array microscopy and light microscopy did not differ significantly with respect to the number/percent of correct decisions rendered (t=0.552, p=0.6376) or equivocal decisions rendered (t=2.449, p=0.0917). Pathologists rated 95.8% of array microscopy virtual slide images as good or excellent. None were rated as poor. The mean viewing time for a DMetrix virtual slide was 1.16 minutes. The DMetrix virtual slide processor has been found to reduce the virtual slide processing cycle more than 10 fold, as compared with other virtual slide systems reported to date. The virtual slide images are of high quality and suitable for diagnostic pathology, second opinions, expert opinions, clinical trials, education, and research.

Digital imaging in pathology: theoretical and practical considerations, and applications

Digital imaging is rapidly replacing photographic prints and Kodachromes for pathology reporting and conference purposes. Advanced systems linked to computers allow greater versatility and speed of turn-around as well as lower costs, allowing the incorporation of macroscopic and microscopic pictures into routine pathology reports and publications. Digital images allow transmission to remote sites via the Internet for primary diagnosis, consultation, quality assurance and educational purposes and can be stored and disseminated in CD-ROMs. Total slide digitisation is now a reality and has the potential to replace glass slides to a large extent. There are extensive applications of digital images in education and research, allowing more objective and automated quantitation of a variety of morphological and immunohistological parameters. Three-dimensional images of gross specimens can be developed and posted on websites for interactive educational programs and preliminary reports indicate that medical vision systems are a reality and can provide for automated computer generated histopathological diagnosis and quality assurance.

Digital imaging applications in anatomic pathology

Digital imaging has progressed at a rapid rate and is likely to eventually replace chemical photography in most areas of professional and amateur digital image acquisition. In pathology, digital microscopy has implications beyond that of taking a photograph. The arguments for adopting this new medium are compelling, and given similar developments in other areas of pathology and radiologic imaging, acceptance of the digital medium should be viewed as a component of the technological evolution of the laboratory. A digital image may be stored, replicated, catalogued, employed for educational purposes, transmitted for further interpretation (telepathology), analyzed for salient features (medical vision/image analysis), or form part of a wider digital healthcare strategy. Despite advances in digital camera technology, good image acquisition still requires good microscope optics and the correct calibration of all system components, something which many neglect. The future of digital imaging in pathology is very promising and new applications in the fields of automated quantification and interpretation are likely to have profound long-term influence on the practice of anatomic pathology. This paper discusses the state of the art of digital imaging in anatomic pathology.

Telepathology overview: from concept to implementation

Telepathology is the practice of pathology at a distance by using video imaging and telecommunications. Significant progress has been made in telepathology. To date, 12 classes of telepathology systems have been engineered. Rapid and ultrarapid virtual slide processors may further expand the range of telepathology applications. Next-generation digital imaging light microscopes, such as miniaturized microscope arrays (MMA), may make virtual slide processing a routine laboratory tool. Diagnostic accuracy of telepathology is comparable with that of conventional light microscopy for most diagnoses. Current telepathology applications include intraoperative frozen sections services, routine surgical pathology services, second opinions, and subspecialty consultations. Three telepathology practice models are discussed: the subspecialty practice (SSP) model; the case triage practice (CTP) model; and the virtual group practice (VGP) model. Human factors influence performance with telepathology. Experience with 500 telepathology cases from multiple organs significantly reduces the video viewing time per case (P < .01). Many technology innovations can be represented as S-curves. After long incubation periods, technology use and/or efficiency may accelerate. Telepathology appears to be following an S-curve for a technical innovation.