NEMA, Suite 1752
1300 North 17th Street
Rosslyn, VA 22209
Ph: (703) 841-3285
HTTP://DICOM.NEMA.ORG
MINUTES
DICOM WORKING GROUP TWENTY-SIX
(Pathology)
May 17, 2008
Toledo, Spain
Called to order: 10:15 AM
Meeting closed: 2:00 PM
Presiding Officer: Bruce Beckwith
Attendance:
Company
3DHistech
ADICAP, APHP, INSERM
Aperio
Charite Berlin
College American
Pathologists
Dako
Dmetrix
EPFL
GE Healthcare
Harris Corp
Hospital Evora
IHE-J
Kocknas Univ Technology
Mass General Hosp
Mass General Hosp
Olympus/Soft Imaging
Philips
Philips
Person
Varga, Viktor
Le Bozec, Christel
Eichhorn, Ole
Schrader, Thomas
Status
Rep
Rep
Rep
Observer
Beckwith, Bruce
Schmid, Joachim
Lacomb, Lloyd
Ansorge, Michael
Dekel, Shai
Lee, Andy
Goncalves, Luis
Tofukuji, Ikuo
Punys, Vytenis
Gilbertson, John
Yagi, Yukako
Schilling, Tobias
Kneepkens, Rik
Schryvers, Mariel
Rep
Observer
Alt
Observer
Alt
Observer
Observer
Rep
Observer
Rep
Observer
Observer
Alt
Alt
1
_______________________
DICOM WG-26 – Pathology
May 17, 2008
Philips
Rorigo Hospital
TRIVBN
Van Wijngaarden, Hans
Gasparetto, Alessio
Klossa, Jacques
Rep
Observer
Rep
Univ Castilla-La Mancha
Univ. of Tampere
Univ. of Tampere
Univ. Udine
Zeiss
Bueno-Garcia, Gloria
Isola, Jorma
Tuominen, Vilppu
Bortolotti, Nicola
Bauer, Johann
Clinch, Noah
Della Mea, Vincenzo
Observer
Observer
Observer
Observer
Alt
Observer
Observer
Work Items assigned:
1. Ole Eichhorn will incorporate the results of the discussions from Denver and
Toledo and distribute the updated draft of the WSI supplement with the
index/map object that we discussed.
2. Bruce Beckwith will look into scheduling the 2009 meetings of the workgroup.
3. Jacques Klossa, Christel Daniel, and John Gilbertson will decide among
themselves who will attend the WG-06 meeting in Cardiff, Wales to discuss the
final text of Supplement 122.
The meeting began with administrative items, including introductions around the table.
This was followed by Bruce giving a summary of the aims and progress of the working
group for the benefit of new attendees.
1. Supplement 122 Update:
Supplement 122 has been approved by letter ballot. Comments were received from 2
members and these were addressed. Questions from the SNOMED group were also
addressed. The final text should be approved at the WG-06 meeting at the end of June in
Cardiff, Wales.
2. Whole Slide Imaging Issues:
Since we had a number of new attendees who were not completely familiar with the
proposed mechanism for handling whole slide images in DICOM, and the progress made
at the March 2008 meeting, we started with a discussion of the differences between the
proposed tiling approach and a plain JPEG2000/JPIP approach. There was significant
discussion regarding the two, but it was stressed that the pyramidal approach would fully
support having only one layer in the pyramid, which could be a JPEG 2000 format image.
Additionally it was noted that no known whole slide imaging vendor is using JPIP as
their access method at this point. At the end of the discussion, all present agreed that it
would be important to move forward first with the pyramidal/tiling approach and then
deal with the pixel dimension and image size limits later. We also agreed that in order
2
_______________________
DICOM WG-26 – Pathology
May 17, 2008
for adoption and backwards compatibility, it would be most desirable to be able to store
the image in a PACS system as opposed to simply storing a link to a separate image
server.
We reviewed the general principles of the storage proposal elaborated in Denver, that in
order to make the structure as flexible as possible and allow as much innovation as
possible, very few absolute limitations with regard to the contents of the pyramid would
be imposed. However, in order to simplify some aspects, we agreed that with a particular
“slice or layer” of the pyramid, all tiles must be the same size and shape and must not
overlap (no duplicate pixels) and must have the same image format (image file format,
compression, color channels, etc.) and represent the same “z” plane. Additional z-planes
(representing different focal planes) can be represented as a different layer in the pyramid.
In this way one pyramid might have multiple layers at the same resolution, each
representing a different color channel, compression scheme, focal plane, etc.
We also discussed two ancillary images that should be optionally included in a WSI
image object – the label image and a low power image of the entire slide (not just the
region scanned at microscopic resolutions). We agreed that there should be a way of
indicating whether a particular tile or layer contains personally identifiable health
information, such as a name, medical record number, accession number, etc. We also
thought it would be useful to include fields which could contain decoded information
from any barcodes and text present in order to avoid viewers having to decode this
information using optical character or bar code recognition.
There was discussion regarding whether it would be useful or possible to store
information regarding the areas where the original raw images have been ‘stitched’ or
merged in order to create the whole slide image. This would not apply to all capture
devices, but it might be helpful in cases where image analysis would be used on the
whole slide image in order to highlight known areas with possible artifacts. We decided
that a new type of layer would be useful, which could contain “mapped” data. This layer
could be sparse, like any other layer. It could be used at any resolution, not just the
highest resolution. We envision that it could store a focus map, a stitching seam map, or
a map of areas that have been preprocessed in a particular way, for example. This would
in theory allow storage of pixel by pixel metadata, which is used already in some
geoimaging applications.
We next discussed the ‘index’ object that would be needed to keep information regarding
each layer and tile. We agreed that for each layer, it would be desirable to allow for the
inclusion of any known physical data, such as the thickness or depth of field of a focus
plane. We also agreed that there should be a relative number assigned to any “z” focal
planes, starting with the plane closest to the glass slide surface. We also thought that
each layer should have a human readable description to facilitate user selection of layers
if needed. We also thought each layer should have a color model description, such as
RGB, YCC, grayscale, etc. We also thought that for situations where the image data was
outside of the visual frequencies, it would be useful to have an optional field for a
suggested color to display data collected at such frequencies.
3
_______________________
DICOM WG-26 – Pathology
May 17, 2008
3. Meeting Schedule
We reminded attendees of the meeting schedule for the remainder of 2008.
 Sept. 27, 2008 in conjunction with CAP’08 in San Diego, CA.
Some possibilities for 2009 meetings were discussed, including a meeting in Washington,
DC in early 2009 to allow for overlap with WG-06 meeting. Another possibility favored
by some participants was a May/June meeting in Iceland since this would minimize
overall travel. Another possibility was the main European pathology conference, which
is in Florence in Sept. 2009. We will decide upon the schedule either at the next meeting
or on the listserve.
Reported by:
Bruce Beckwith, Co-Chair
May 29, 2008
Reviewed by counsel:
May 30, 2008
4
_______________________
DICOM WG-26 – Pathology
May 17, 2008