Outside US, Digital Path Moves Ahead Rapidly

Shortage of pathologists is one reason some countries moved quickly to adopt digital pathology

CEO SUMMARY: Implementation of digital pathology and whole-slide imaging systems in the United States lags behind that of other countries for two reasons. One is a more acute shortage of pathologists in those countries and the other is a less restrictive regulatory environment. In some locations outside the United States, pathologists have adopted fully-digital operations, eliminating the need for microscopes in their offices.

WHILE THE FDA HAS CLEARED a second digital pathology system with whole-slide imaging (WSI) for use in clinical diagnosis in the United States, pathologists outside of this country have adopted digital pathology and WSI systems at far greater rates.

The FDA’s clearance in May for Leica Biosystems to market its Aperio AT2 DX whole-slide imaging system in the United States for clinical diagnosis will have a positive effect on the digital pathology marketplace, one researcher said. But the United States will continue to lag behind other countries in its adoption of these systems, added the researcher, Sylvia L. Asa, MD, PhD, a consultant at the University Health Network in Toronto.

Asa views the FDA clearance of the Aperio system as a positive step for pathologists in the United States. “The more options there are, the more market forces push competition and there will be more uptake of the technology,” she said. From 2000 until 2015, Asa served as Pathologist-in-Chief and Medical Director of the Laboratory Medicine Program at the University Health Network in Toronto, where she oversaw the implementation of digital pathology systems that provided lab services to more than 20 hospitals in Ontario. She also is a member of Leica’s medical advisory board.

Increased competition among vendors of digital pathology systems is not the only benefit of the FDA decision, Asa added. “The real driver for full adoption of digital pathology is being able to do something with whole-slide imaging that we cannot do with glass and microscopes,” she explained.

Multiple Benefits of DP

At the University Health Network in Toronto, digital pathology systems have multiple benefits. “UHN had the ability to provide high-quality subspecialty diagnostics to multiple public institutions,” she commented. “The same model will apply to multisite organizations in the United States.

“The ability to add image analysis is a driver,” she continued. “And as artificial intelligence applications emerge, there will be a great push for pathology to digitize slides.”

In Canada and other countries, the adoption of digital pathology systems has progressed much faster than it has in the United States for two reasons, Asa commented. “First is the significant shortage of pathologists in many countries that created a need for access from remote locations,” she said. “The second reason is the relative laxity of regulatory restrictions in other countries.”

Used for Remote Diagnosis

In Toronto, Asa and other pathologists have at least 15 years of experience with digital pathology. “In 2004, Health Canada approved telepathology, allowing the University Health Network to initiate remote diagnosis, initially using a robotic microscope,” she noted.

“By 2006, we moved to whole-slide imaging using the Aperio system that Leica subsequently acquired,” she said. “UHN moved to full primary diagnosis in 2011 using the AT2 scanner fully integrated with our Cerner CoPath LIS.”

“Other countries also have implemented digital pathology for primary diagnosis,” Asa added. “The LabPON group in the Netherlands is well known for its use of the Philips IntelliSite Pathology System. In Kalmar, Sweden, Dr. Sten Thorstenson has been using WSI since 2006 and two years later expanded its use across his department in University Hospital Linköping. In 2014, Thorstenson went exclusively digital.

“On a recent visit to that department, I saw pathologists who no longer had microscopes in their offices because they use WSI with Hamamatsu scanners integrated with their SymPathy LIS for routine primary diagnosis,” Asa continued. “An article on this development will be published soon.

“In Québec, a group has implemented WSI for consultation in remote parts of the province,” she added. In 2014, Dr. Bernard Tetu and colleagues published an article about this effort in Diagnostic Pathology, titled, “The Eastern Québec Telepathology Network: a three-year experience of clinical diagnostic services.

“We can see from these few examples the effect of easier regulation in other countries versus that of the United States,” Asa said. “But now that two DP systems have this approval in the United States, I expect other companies will follow. That means pathologists in the United State are sure to start investigating the advantages of digital pathology.

“Outside of the United States, regulators may have recognized the more significant need for pathologists because it is better to have access to a pathologist using WSI than to have no access to a pathologist at all,” she added.

“Consider the initial position of Health Canada on this issue,” Asa said. “Since pathologists examine whole-slide images just as they examine slides under a microscope, and since the microscope was never approved, regulators relied on the judgment of pathologists once the actual equipment was validated.

“By comparison, the FDA has been far more rigid, and in some ways perhaps too rigid,” Asa remarked. “Being extremely cautious about the validity of WSI is appropriate, of course, because, as we have seen, there have been technical failures.

Variability in Different Labs

“On the other hand, every lab has variations in stain quality that result in different color patterns, and every pathologist has different preferences for light intensity,” she said. “Yet the FDA has required validation of specific settings that do not affect diagnostic interpretation and may even get in the way of some pathologists.

“For example, the requirement for expensive medical grade monitors (as some vendors have proposed) creates a financial barrier,” she concluded. “And, in my opinion, and in the opinion of others with fairly broad experience in Toronto and in Sweden, such monitors are not necessary.”

Contact Sylvia Asa, MD, PhD, at pathlady01@gmail.com.

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