Ask a gaggle of anatomic pathologists what their most important tool is, and they will almost certainly tell you it is their microscope. Ask them who their most intimate friend is and they may tell you the same thing. We know every metallic curve and protuberance, every knob and dial. Line up five microscopes in the dark and I doubt any of us would have any difficulty identifying our own by feel alone. We have chosen each eyepiece with care and selected the magnification we want on each objective. Those of us who do lots of very high power work such as examining blood smears or bone marrow aspirations do our best to keep the immersion oil we use from infiltrating every crease and crevice, not always with success.
I am on the third 'scope of my professional career, an Olympus model with an ergonomic head and five different magnifications. It has a video attachment so that I can share my findings with my colleagues and take photographs, but like every pathologist for over one hundred years, I am looking through my eyepieces at an actual glass slide when making my diagnosis. The dimming of that era is beginning. The microscope may be on its way to joining the typewriter and the land telephone line in the Smithsonian Museum Hall of Relics.
There has been much interest in "liquid biopsies," extracting DNA from a patient's bloodstream to diagnose cancer and other diseases. Progress has been made, but widespread utilization is still more than a few years away. The change I am talking about is happening now. In April the FDA gave Royal Philips, a Dutch firm, permission to market its Intellisite digital pathology system for primary diagnosis in the US. What is the Intellisite and why could it spell the end to my intense affair with my microscope?
First let us examine how the slide under my microscope objective was made, and how it got to my desk.
- The biopsy tissues we receive are transported to us "fixed" in formalin which prevents deterioration.
- Our histology team then processes the tissue (we use a special laboratory microwave for the processing) to prepare it for paraffin infiltration.
- The tissue is placed in a plastic cassette which is then filled with paraffin wax. The wax also infiltrates deep into the tissue, solidifying it.
- A histotech cuts the tissue block into thin sections, which float on a water bath and are scooped onto a glass slide.
- The slide is stained with a variety of dyes and passed on to the pathologists.
- The pathologist examines the slide under the microscope and determines the proper diagnosis.
So what changes with digital pathology? Virtually nothing, until the end game. Instead of the slide being turned into the pathologist, the digital system photographs the entire slide creating a virtual image that can be seen on a local digital network, or with enough bandwidth, on the Internet. Instead of moving the slide along the flat stage of a microscope, we maneuver the image using a mouse or keyboard. Just like the original glass slide, the virtual image can be viewed at varying magnification. And just as radiologists can read an x-ray from anywhere in the world, pathologists will have the same ability with digitized slides.
Now that Philips has gotten the OK to market this system, are changes going to happen overnight? Not at all. Radiology changed quickly because it was possible to eliminate x-ray film and go directly to digital images. But as we have seen, in pathology the glass slide must still be prepared, a time and labor intensive operation. Digitizing doesn't eliminate any of this; it is an additional step. And the equipment won't be cheap.
Other hurdles? Reading a digitized slide takes some training. I have had the opportunity to examine them in training courses and my comfort level in making a diagnosis definitely doesn't match the confidence I have with the glass slide on my 'scope. In addition, state health agencies may restrict how and by whom slides of patients in their states can be read.
The early use of digital will probably be in consultation, seeking an expert opinion on a particularly tough case. Currently, if I want to do that, I package the glass slide and FedEx it to my consultant. Moving the case from the recipient hospital loading dock to the consultant's desk may add a day or two to the process. An electronic way to send the case eliminates much of this delay. Voila! Instant consultation. There will also be some use in remote hospitals and in small hospitals that are part of larger medical systems but don't necessarily have pathologists on site.
But for now, I can continue to have a relationship with my microscope. I think she will last as long in this business as I do . Of course, I said that about my old flip phone too!
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