Download Telepathology: A Netwotk of Microscopes

Javier J Rodríguez, MD, FCAP
TELEPATHOLOGY: AN OVERVIEW
“Telemedicine, and consequentially telepathology is
not a science of the future but of the present and is
here to stay, to the point that today‘s physicians are
more and more required to have at least some
knowledge of telemedicine.”
Telepathology and Pathology at Distance: an Overview Dražen M. Jukiæ, Carlo B. Bifulco1
Let’s telepath…
 Some definitions and things to be familiar with
 How is a photomicrograph digital image
created?
 A brief history
 Benefits
 Three different approaches to telepath
 Static images interchange
 Real Time Microscopy
 Virtual slides
 Some predictions…
Some definitions
 Telemedicine:
 “Telemedicine is a method by which patients can be examined,
investigated, monitored, and treated, with the patient and the
doctor being located at different places” (Kumar S. Introduction
to Telepathology. Telepathology, 2009)
 Telepathology:
 Branch of telemedicine that uses technology to transfer “image
rich pathology data” between “remote locations” for diagnosis,
education and research
Some definitions:
 Digital Image Resolution: width x height.
 Pixel: “picture element”. The number of pixels




comprising an image determines the “resolution of the
image” Each pixel (dot) can be only one color. Each
pixel storage information can be 8 bit, 12 bit, 16 bit,
24 bit at 32 bit (Color Depth)
Determines the size of the file, not the projected
resolution, or DPI
It does not imply physical size.
The greater the resolution the more data information
available for the image
Higher resolutions are useful for algorithmic analysis.
Some definitions:
 DPI: Dots per inch. Better use the term Pixel per inch. Is
a property of a printed or displayed image and is
dependent on the physical size of the output.
 CCD: Charged Couple Device: The retina of the digital
camera. An array of light sensitive elements (photosites)
that produce voltage when exposed to light. It is an
analogue device!!!
 Digital Camera resolutions: Total number of elements in
the array. The higher the number of photosites the
higher the resolution. Are photosites the actual physical
representations of pixels?
Some definitions:
 “ Resolution is also often quoted as the size of charged
coupled device (CCD), which is effectively the number of
pixels on the chip. It should be noted, however, that the
size of the individual pixels varies amongst different
types of CCDs. For microscopy, a pixel size (square) of 6.7
micrometers is thought to be ideal.”
How is a digital image
created?
 It’s an analogue world out there and somebody
has to stop it!!!
 The conversion from analog to digital is
equivalent to “ freezing real time instances” and
assigning numbers to describe each frame: The
Kodak moment!!
 The rest is a show of force of number crunching
and manipulations
How is a digital image
created?
 A CCD imager consists of a large number
of light-sensing elements arranged in a
two-dimensional array on a thin silicon
substrate.

The light-sensing photodiode elements
of the CCD respond to incident photons
by absorbing much of their energy

The photosites voltage are digitized to a
value by the A/D converter: the CCD
undergoes readout

Values stored in the digital image specify
the brightness and color of each pixel.

The values of all photosites are stored
and manipulated in the computer
http://www.microscopyu.com/articles/digitalimaging/digitalintro.html
A brief history
 Too brief of a history
• Term coined in 1986 by Ronald Weinstein
at Rush:
• Weinstein RS. Prospects for telepathology. Hum Pathol
1986;17:433-4
 Video conferencing dedicated digital/phone
lines:
 “Telepathology is the practice of diagnostic pathology performed at a
distance, with images viewed on a video monitor rather than directly through
the (light) microscope”.
 1990-2000: Internet era: Static images sharing-AFIP
 Current trend: whole slide virtualization
Cons and Pros:
 Telepathology has proven useful for service to remote areas but it
is still debatable how practical or cost effective it could be.
 The issue of developing countries costs vs expertise. Technology
costs will make the accessibility of expertise more reachable.
• Not necessarily a substitute for conventional diagnostic processes
but an improvement and/or another tool for the pathologist.
• Legal issues are still up in the air and often incompletely addressed
• Benefits are really dependent on the type of technology used and
the purpose: Static images, vs real time vs virtual slide
Static Image Interchange:
 Exemplified by AFIP consultation service.
 Selected images of a case/slide are captured
and transferred to consultant.
 Application:
 Education: classic diagnostic criteria
 Consultation: Emphasize interest areas
 Presentations and tumor boards
 Pathology reports content
 Image analysis: high resolution images.
Static Image Interchange:
 Benefits:
 Fast image transfers with today internet speeds
 Low cost investment: Conventional microscope +
Digital Camera: 5-10K
 Short time learning curve.
 Shortcomings
 Limited view of field
 Planes of focus are not captured
 Selection by non-expert may miss important
areas.
 Adds cost to pathology reports content (debatable!!)
Real Time Microscopy:


Slide is shared in real time.
Applications:




Benefits:






Long distance education
Real time long distance consultation
Frozen sections
Wider field view
Real time discussion
Relatively low cost: 15-30K
Relatively easy to sep up.
Planes of focus may be addressed
Shortcomings:




Dependable on assisted operator (although new models use robotics)
Requires higher than average upload bandwidth (expensive above T1 bandwidth)
Dependable on line/internet condition. The higher the resolution, the more bandwidth
it consumes.
Requires special software for viewer/consultant end.
Whole Slide Imaging
 The long waited technology: An digital image of the
whole slide
 Eliminates all shortcomings of other modalities except
cost
 Most renown vendors: Aperio and Bioimagene
 Applications:




Anytime/anyplace long distance education.
Anytime/anyplace long distance consultation.
Presentations and tumor boards
Image analysis: Immunohistochemistry analysis. More
reproducible than human eye.
 Automation
 Slide archival
 Quality assurance
Demo:http://www.uscap.org/
Whole Slide Imaging
 Shortcomings:
 Way expensive systems (>120K)
 Steep learning curve
 Large file size, >1gb/full slide (this can vary.)
 Slow to scan 2-8 minutes per slide depending on
magnification
 Special software required
Some predictions:
 Will pathologists follow the radiologists path?
 Argument 1: “ In most cases the goal of the radiologist
is to give a differential diagnosis…for pathology the
goal is a definitive diagnosis” John S Sinard, Practical Pathology
Informatics
 Argument 2: Radiology sets of images not more than
200-500. Pathology sets of images >10 K
 Technology cost will go down but software will increase
 Speed will reach seconds for scanning
 Adoption will be slow given the high costs and the need to
cost contain
 10-20 years: adoption of a complete digital microscope.