Werner Schlake MD
President National Professional Organisation of Pathologists
E: [email protected]
Peter Hufnagl PhD
Telemedical Center Charité (TMCC)
Head of Digital Pathology and IT
Charité – Universitätsmedizin
E: [email protected]
The future of telepathology depends on technical progress in data storage and transmission. Telepathology has made a big step into the future with virtual microscopy, which makes a complete scan of slides holding human tissue or cells. There is no need to select pictures from whole slides to use them for further diagnostic purposes. The whole slide is at the command of the pathologist and he can work with it on screen in the same way as with the conventional microscope.
Second opinions are delivered much faster and seem to be as precise as those made with conventional diagnostics. A 2005 study by the German Pathologists Professional Association together with the University Institute of Pathology of the Charitè in Berlin compared the conventional method with the telepathology procedure. A specimen was mailed to a colleague for a second opinion, while a third opinion was also rendered on the basis of exclusively digital material. This study was the first large-scale, Europe-wide project on the quality of teleconsultation. The findings were based on selected pictures of the slides. The second part of the study will be based on digitalised slides and results are expected by the end of 2006.
Teleconsultation today means above all the professional exchange between pathologists. Pathology is a broad medical discipline and we have neither the financial nor staff resources to ensure that each pathologist is an expert in every aspect of the field. Still, hospitals and physicians do need the services of local or at least regional “generalist” pathologists. However, we also need access to specialist knowledge – for example for lymphoma or kidney diagnostics. If telepathology allows a regional pathologist to work online with a reference centre for lymphomas or with a consultation centre, the entire range of expert pathology knowledge and services becomes available – even in remote areas.
This is a fascinating development that is still in its pilot stage. Scanning technology is one of its exciting innovations. The slide that pathologists usually examine under the microscope is scanned. Therefore, they do not have to generate, store and transfer several images of a slide but only one scanned “virtual” slide. Then pathologists can view this slide in different magnifications the same way as with a conventional microscope.
This solves a problem that was considered indecipherable until now. In addition, scanning technology works at an acceptable speed. Previously, one needed about an hour to scan one slide. Now it is down to one slide in three minutes. We can prepare a whole set and it will be documented and marked with all the necessary data before the actual scan. We will be able to work on screen using virtual microscopy just as pathologists do now with conventional microscopes.
A major additional advantage lies in archiving. In Germany, pathologists are required to archive every single slide for 10 years. Since these are glass objects, we have to store tonnes of glass slides. Also, we have to be able to quickly retrieve every single slide. Digital archives would make life much easier. It is not yet sure, though, that a digital archive can really replace a physical one.
In an intricate procedure, the water is extracted from the tissue specimen and replaced by paraffin. Next, this solidified specimen is embedded into a large paraffin block. Then, very thin sections are cut off this block and dyed. These thin tissue slices are used for diagnosis. Pathologists are increasingly asked to also archive the “leftovers” of the paraffin blocks that they cut the sections from. By way of example, let’s look at a new treatment for a certain type of breast cancer that was recently developed. If the tumour cells carry a certain amount of Her2/neu proteins, an antibody therapy can be initiated. For the patient concerned, this is an interesting alternative – with this antibody therapy a surgical intervention is no longer required. If a patient who has been diagnosed with breast cancer a few years ago considers such a treatment, the pathologists first have to analyse the tumour cells. To do this, they can examine the original paraffin block – if it had been archived. If not, the patient has to undergo another biopsy. New antibody therapies are in the pipeline. Pathologists who examine the tumour tissue make a decision based on their findings whether these highly expensive therapies can be performed, and therefore play a key economic role. With a digital and a physical archive of paraffin blocks all possible questions can be answered. With a digitalised archive only, this might not be possible. From this, we could conclude that digital microscopy spells the end of the traditional microscope.
The digital procedure will perhaps replace the conventional microscope in certain routine diagnostics. The pilot study found that digitalisation offers a number of possibilities that the traditional microscope cannot provide. For example, on screen we can display an entire overview over several specimens on one screen – in some cases, that is of extraordinary importance. Also, if a tumour has been stained in different ways, we can view and compare them all at the same time on screen. This cannot be done with a conventional microscope. In addition, with virtual microscopy we can quickly determine percentage distributions. A software-based system can tell us that 20% of the tumour cells are oestrogen-positive, and 80% are negative. Today, we use more or less vague quantitative approaches. We can also perform analyses using a proliferation marker that tells us what percentage of cells are proliferating. Here, digitalisation offers many possibilities. Virtual microscopy will take over certain core tasks of the conventional microscope, but first we have to prove that the digital procedure provides the same level of quality as the conventional one.
International Academy of Telepathology, Germany
German Professional Organisation of Pathologists
Union Internationale contre le Cancer, Telepathology Consultation Centre