Toronto Pathologists Use Whole-Slide Imaging

Digital pathology and whole-slide imaging increase concordance and pathology productivity

CEO SUMMARY: It was the “frozen section problem” and productivity issues that led pathologists at the three-hospital University Health Network (UHN) in Toronto to implement a fully-digital pathology system with whole-slide imaging in 2006. Use of digital, whole-slide images makes it faster to report results to the surgeon, while making it easier to involve colleagues in difficult cases. Now UHN’s pathologists use the system to support hospitals 400 miles away.

IT WAS MAJOR NEWS LAST MONTH when General Electric and the University of Pittsburgh Medical Center (UPMC) announced that they were forming a $40 million joint venture specifically to develop and bring to market an integrated digital pathology system. Given GE’s prominent role in digitizing radiology and its deep pockets, this joint venture attracted widespread attention in health- care and within the pathology profession as well (See TDR, May 27, 2008.)

Changing Surgical Pathology

Clearly, there are revolutionary forces gathering momentum in surgical pathology, and the GE–UPMC joint venture is just one example. For pathologists who would like to see a glimpse into the future of digitized pathology and how it will change long-standing practices in surgical pathology, then a site visit to the pathology department at the University Health Network (UHN) in Toronto, Ontario, would be enlightening.

Take frozen sections, for example. At the three hospitals of UHN, digital pathology and whole-slide imaging has improved the clinical quality of pathology professional services provided to referring surgeons, while increasing the productivity of individual pathologists.

At the heart of this new workflow arrangement for frozen sections and surgical pathology is the ScanScope system from Aperio Technologies, Inc., in Vista, California. Using this system, UHN pathologists can scan frozen section slides and create a digitized, whole-slide image in less than two minutes.

Images of these digital slides are available to a pathologist for immediate viewing on a desktop computer. As a result of this new system, computer monitors have become like virtual microscopes that allow pathologists remote access to images to deliver consistent and accurate results for primary diagnosis.

In the United States, the FDA has not approved the use of digitized slides for diagnosis. Therefore, pathologists in the U.S. cannot use the same digital pathology system that the pathologists at UHN use for primary diagnosis.

“Implementing a fully digital pathology system provided no strategic business advantage for us here north of the border,” explained Andrew Evans, M.D., Associate Professor of Pathology at UHN in Toronto. “But there is certainly an advantage in terms of increased efficiency. Moreover, without question, our work in the digital pathology environment allows us to predict with confidence that these developments will revolutionize the way pathology is practiced.

Improving Workflow

“As a result of using whole-slide imaging, we have maximized pathologist efficiency in the institution,” he said. “Previously, we had an inefficient system—in part because the University Health Network has a three-site academic medical center in downtown Toronto. All the pathologists sit at Toronto General Hospital (471 beds) but across the street is the Princess Margaret Hospital (220 beds), which is a tertiary cancer referral center. Then, about a mile to the west is the Toronto Western Hospital (256 beds), which is home to the Krembil Neuroscience Centre, one of the largest neurological facilities in North America.

“For these three facilities, our old system didn’t make any sense from a pathologist workflow perspective,” continued Evans. “Because all the pathologists are at the Toronto General site, we often had someone sitting in one of the other two hospitals twiddling their thumbs much of the time. The move to a fully-digital pathology arrangement has greatly improved the productivity of individual pathologists.

“More important, the whole-slide imaging system has benefited patient care,” said Evans. “Now, any time we have a difficult case, it is fast and easy to have multiple pathologists look at that case all at the same time. That is a change from the past, when a pathologist was working alone at one of the other facilities and the use of glass slides limited the possibility for consultation on difficult cases.

“That’s all changed with the fully-digital pathology system. Because it is so quick and simple to share cases, our pathologists have developed a low threshold for showing diffi- cult cases around,” he added. “As a result, our accuracy has been very good, meaning concordance between initial and frozen section interpretation is quite high.”

UNH’s move to digital pathology began more than four years ago. “We knew about the history of telepathology—particularly in Scandinavia and Norway in the late 1980s and early 1990s,” recalled Evans. “We thought telepathology would be a viable alternative to our workflow at that time. We developed and implemented the technology and started using a robotic microscope in the fall of 2004.

“For about two years we used a robotic microscope, and it helped us in many ways,” he continued. “But because the technology was not advanced enough, the arrangement had limited value.

“With this telepathology arrangement, when viewing the frozen section slides from the other two hospitals, the pathologist at Toronto General could adjust the focus, but the robotically-controlled system required the pathologist to review a series of compressed images,” noted Evans. “These images captured only one field at a time. The pathologist was required to review the image and then move to the next field and repeat the process until he/she reviewed the whole section. This usually took about 10 minutes, sometimes longer.

High Accuracy Rates

“During the time we were using the telepathology system, our research group was using some Aperio instruments,” stated Evans. “The decision was made to bring digital imaging to hematology and oncology. So, between pathology and hematology, we put the money together to get a scanner and make the switch to whole-slide imaging.

“When this first digital system was set up, all the blood films and marrow aspirates were scanned and sent to a server on the west end of the city,” Evans said. “We did this because the digital files were so large.

“Once these images were scanned, any clinician could access them in the patients’ electronic charts at any workstation in any hospital,” Evans continued. “A pathologist could click on the digital image and review the slide. That was back in 2003, and that step paved the way for digital imaging in pathology.

“Government grants helped us purchase and implement this equipment. That’s because
the government is keen
on digital healthcare technology to provide consultation services to underserviced areas.”
—Andrew Evans, M.D.

“Given the business relationship that UHN already had with Aperio, we next considered switching to a digital system similar to what was in use in hematology,” Evans explained. “When our pathology department implemented the fully-digital system, I believe we were the first site in the world to use whole-slide imaging for primary diagnosis for patient care.

“In October 2006, we started using the Aperio system for primary frozen sections. Combined with the robot and the Aperio scanner, we have used this arrangement for about 1,000 cases in less than two years,” Evan said. “The system is ideal because, if the digital instrument were ever to fail, we are a 20-minute walk away from the glass slide. During this two-year period, there have been only about four times when the pathologist had to walk over to the other site because of a problem with the instruments.

“Despite those few problems, this fully-digital pathology system is performing successfully for frozen sections and we have learned how to prevent the problems we had initially,” he observed. “The big difference—and benefit—is improved turnaround time. We typically deliver an answer in 15 minutes. Also, as noted earlier, our pathologists can quickly share difficult cases and that’s improved our concordance.

“Workforce issues in Canada are another reason why this digital pathology system is a success,” Evans added. “Adequate staffing of pathologists is a challenge. Using technology to extend pathologists and make them more productive is widely supported. Government grants helped us purchase and implement this equipment. That’s because the government is keen on digital healthcare technology to provide consultation services to underserviced areas.

“Here’s an example,” Evans said. “We entered into a partnership with a group of hospitals in Timmins, Ontario, about 400 miles to the north. Most of the time, they have only one pathologist on site. For one week each month, no pathologist is on site for primary cases. Most of that work is sent to us to report. And, when there are frozen sections or ultra-rush biopsies that need triaging, we receive digitized, whole-slide images and report these cases by digital assessment. This system is working very well.”

An Ideal Pathology Solution

Other hospitals in Canada, having seen the results achieved by the UHN pathology department’s use of digital pathology images, are considering using whole-slide imaging systems for primary diagnosis in their pathology departments as well. THE DARK REPORT observes that the Canadian experience is one example of how digitized pathology systems are being used in the healthcare systems of other developed countries. Improvements in turnaround time and in the concordance of frozen sections at University Health Network in Toronto demonstrate two ways digitized pathology systems can contribute to better patient care and improved clinical outcomes.


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