Radiology and pathology are cornerstones of cancer diagnosis, the former allowing tumors to be accurately located and biopsied and the latter providing confirmation of their malignancy. Radiology has already ‘gone digital’. Without that process having taken place, many of today’s computer-aided imaging modalities would not be possible. Today, radiologists are just as comfortable looking at radiology images on computer screens as they are examining a conventional film X-ray on a light box. However, the same cannot be said for the world of pathology.
As part of their current practice, pathologists
mount the tissue slices on glass slides, treat them
with appropriate stains and examine them through a
microscope. Interpreting what they see is a
time-consuming process and requires a great deal of
skill and experience. Few tools exist to accurately
quantify features of the images that they see
through their microscopes.
Increased demand
There is an ever-increasing demand for
pathology-based diagnosis, particularly in oncology.
The demographic shift to larger numbers of people in
older age-groups means that there will be more
people suffering from disease, much of it cancer. In
addition, today’s high levels of obesity will expose
a greater proportion of the population to the risk
of cancer at an earlier age. On top of these
factors, the number of therapy options becoming
available will demand better patient stratification
and hence more pathology tests per patient.
However, this increased demand is not currently
being matched by the supply of skilled pathologists,
who remain in short supply in most parts of the
world. There is therefore a real need for technology
that improves the efficiency of pathology labs while
also improving the quality of diagnosis.
Going digital
As has already been the case in radiology
departments, the solution may lie in the
digitization of pathology images, not only so that
they can be more easily stored, retrieved, viewed
and distributed but also so that image analysis
software can be employed to help pathologists
quantify what they see.
 Glass slide in prototype slide scanner
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Philips’ integrated solutions for digital pathology
have been designed to accomplish all of these
objectives. They leverage its existing expertise in
medical imaging in radiology (e.g. whole-body CT
scans) and its expertise in radiology Picture
Archiving and Communications Systems (PACS).
Even though a pathology slide is relatively small
(typically 1.5 cm x 1.5 cm), imaging of biological
specimens requires hundreds of millions of pixels.
The front-end of Philips’ digital pathology system
is therefore a highly automated high-resolution
high-speed slide scanner that has been designed to
scan standard pathology slides at a speed of one
slide every 50 seconds (total scanning and handling
time). Featuring 40x optical magnification and a
high-resolution image sensor, the scanner is capable
of producing extremely detailed images. Dynamic
autofocus techniques originally developed by Philips
for Blu-ray Disc players accurately follow the
contours of tissue slices, which are never perfectly
flat.
The associated high-capacity image storage and
viewing system has been designed to efficiently
store, retrieve and view the digitized pathology
images. To assist pathologists in the analysis and
interpretation of these images, the system also
includes image analysis software for feature
recognition and quantification. The software will
also act as a platform for developing additional
functionality that was not possible before, such as
focusing at different depths in tissue samples to
build up 3D pictures of their internal structure.
Improving efficiency
Digitization of pathology images may also open up
new ways of working to further improve the
efficiency of pathology services. For example,
seeking the expert opinion of an external specialist
could no longer involve physically sending slides to
them, and it may no longer be essential to locate
pathology lab technicians and pathologists alongside
one another in the same facility. The ability to
rapidly communicate images between facilities could
even allow the setting up of distributed pathology
services based around virtual networks.
Future collaboration
Philips is already working with leading pathology
departments to evaluate the benefits of the system
in real-world clinical environments. In order to
fully exploit the benefits of digital pathology,
there is still much to be done. For example, no
industry standard comparable to DICOM (Digital
Imaging and Communications in Medicine – a standard
for handling, storing, printing and transmitting
information in medical imaging), currently exists
for digital pathology images.
Philips therefore welcomes partnerships with
organizations that can help to develop such
standards. It is also actively seeking
collaborations with companies that specialize in
histological stains, staining techniques and other
histopathology procedures in order to develop the
system further.
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