Digital Pathology a New Data Source to Transform Medicine

Pam Harrison

October 15, 2014

TAMPA, Florida — The rich trove of data encoded in images taken for analysis by today's pathologists will be mined for its value in the not-too-distant future, according to pathologists here at the American Society for Clinical Pathology 2014.

"Right now, all we are primarily doing with digital data — which is the image itself in digital form — is looking at it," said Ulysses Balis, MD, director of the division of pathology informatics and professor of pathology at the University of Michigan Health System in Ann Arbor.

"The real opportunity for us now is to do computational, quantitative analytics on all of these data. I think imaging informatics will be a big portion of the type of informatics in which pathologists will be involved," he told Medscape Medical News.

The laboratory was among the first part of the hospital to be computerized, said Joseph Mark Tuthill, MD, division head of pathology informatics at the Henry Ford Health System in Detroit.

"When you have a high-volume operation like the laboratory, where you are dealing with millions and millions of samples, it is impossible to proceed without computerization," Dr. Tuthill explained. "We've implemented computerized technology to help us run the workflow of the lab, so we can rapidly access samples, make sure we have the right patient, and make sure the right tests are being ordered, all without having to enter the information into three or four systems," he explained. "But digital pathology is only one aspect of pathology informatics."

Currently, experts can take a standard glass slide and digitize it using a whole-slide scanner about the size of a small toaster. Once digitized, pathologists can look at tissue samples on the computer screen. In the future, those digitized images will be fed into different software programs that will make suggested diagnoses.

New Methods for Diagnosis

"Imagine small, medium, and large pathology practices having digital slide-scanning infrastructure, as part of their collective histology lab, that digitizes either a fraction or the entirety of slides that get generated," said Dr. Balis. For "high-value" cases — typically those involving a potential malignancy — the slides will not only be scanned, the digital information will serve as a substrate for a collection of specialized programs that can review all the surface area of the slides ahead of time, he explained.

This has the potential to change the main job of a pathologist from just screening slides to a "directed review" of slides, focusing on the most worrisome lesions — highlighted by the computer — in the slide set. "Computers don't get bored," said Dr. Balis.

Another immediate advantage of having digitized images accessible in a central computer is that any pathologist can review them. In fact, telepathology — which allows expert pathologists not on site to contribute to the diagnosis, education, and research for each image reviewed — is already widely in use, said Dr. Tuthill.

Dr. Tuthill said he also anticipates that pathologists will be able to do ad hoc testing on existing slides without having to prepare them with any special stain. "Right now, we have to take chemicals and throw them at the tissue to light up the things that we are looking for," he said. But the computer itself can change the way pathologists see the tissue by changing the spectrum of light through which a specimen is viewed.

"Digital staining is not yet being done in clinical practice, but we could use a computer to tag antibodies or different molecules instead of using stains," he explained. "Because the computer can look at many different epitopes on a single glass slide, it becomes many times more efficient than the human eye."

As well as a selection of differential diagnoses for the pathologist to consider, the computer could be of prognostic or even predictive value by suggesting which of several therapeutic agents might be best for an individual patient.

Dr. Balis said he is hopeful that in some, if not all, instances, pathologists will be able to use image data, either exclusively or with relatively few additional data, as a surrogate for expensive molecular tests to predict patient response to a given treatment selection.

"Once you find a correlate between the image space and advanced molecular profiling, it shows you a road map. You might not need to use expensive molecular profiling for general cases, you might be able to just pull that information from the H&E slide, which is really quite amazing," said Dr. Balis.

He even predicts that digital morphology data will be combined with genomic data to generate a more robust classification set, helping the pathologist arrive at the same diagnostic answer as a molecular assay, at a fraction of the cost.

Automation in the Lab

Pathology hasn't lent itself to as much automation as the testing of blood. As long as a lab receives a properly labeled tube of blood, "you can stick it on an analyzer and you could have a lab result in 5 minutes," said Dr. Tuthill. "This information can then flow back into the computer system that clinicians are using to take care of their patients."

Tissue analysis, however, requires a much more complicated approach, he explained. A piece of tissue from a patient who might have melanoma, for example, has to be analyzed and sectioned into pieces, sent back to the histology lab, processed into glass slides, and then sent back to the pathologist, where it can be analyzed for a diagnosis. As with any human endeavor, there are many points along the way where there is opportunity for error.

Dr. Tuthill has spent a lot of time bringing barcoding to the practice of anatomic pathology to minimize the risk of mixing up patients and diagnoses and to ensure that a patient's identity is preserved during all of the necessary steps. "If I ping the slide and the slide is for the right patient, I can't get it wrong. Not only does this process have a huge impact on patient safety, it also has an incredible impact on the cost of lab medicine and testing in healthcare," he said.

"The lab provides 70% to 80% of the data in our medical records, and data drive the decisions that happen in the hospital. Our hands may not be touching the patient, but we touch our patients through data, information, and knowledge," Dr. Tuthill noted. "You can't live without laboratory testing."

Dr. Balis and Dr. Tuthill have disclosed no relevant financial relationships.

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