Communications - April 2009

on how to best combine 2D and 3D imagery. “We seem to be moving to a consensus that the sensitivity and specificity of 2D and 3D are comparable,” Dr. Summers says. “The question is which one do you use as your primary.” Yoshida thinks CAD could soon replace 3D visual fly-throughs for first reads, though expert examination of 2D images—what radiologists called “problem solving”—will still be needed.

2D is important in a virtual biopsy, which depends on flattening the images to simulate what pathologists do when dissecting a polyp. “They will slice it along its length and lay it flat and look at it,” Dr. Summers says. “You do the same thing on the computer.” Some experts, he notes, think such 2D dissection provides faster diagnosing than 3D fly-through.

Seeking improvements

Medical and computer-science researchers are striving to make virtual colonoscopy technology more accurate, affordable, easier to use, and patient friendly.

A technique called dual-energy imaging, for instance, highlights polyps by blending images derived from different radiation doses to increase

“the examination
is done on the data,
rather than the
patient,” says Dr. c.
Daniel Johnson.

contrast, Yoshida says. And graphics processing unit-based rendering is being touted as a faster method of getting images to radiologists, as Kaufman’s group has done. Also, Dr. Summers says his collaborators and him have figured out how to bolster CAD with wavelets on manifolds to reduce false positives by more precisely characterizing polyps. And machine learning and neural nets are the subject of ongoing research.

To increase virtual colonoscopies’ usability, computer scientists are also focusing attention on the PCs that are used for analyzing images. One possibility is off-site image processing, which Yoshida says Massachusetts General Hospital is ready to implement.

Others hope to democratize virtual colonoscopies by getting the software to run effectively on desktop and laptop computers. For example, the Redmond, WA, company FiatLux Imaging employs the Direct3D technology in video games and in virtual colonoscopies. “It’s usually required to run on very heavy-duty, expensive hardware,” says Rosemary Fisher, FiatLux’s clinical application specialist. “That is prohibitively expensive for small hospitals and clinics.” Many of them lack colonography software and have little financial incentive to invest in it before insurers start uniformly reimbursing for virtual colonoscopies. But as spiral CT scanners become more broadly distributed, affordable volume-rendering software, such as FiatLux’s Visualize, might make virtual colonoscopies more available in remote places via telemedicine.

The takeaway message is that virtual colonoscopies are poised to dramatically increase successful colon screening outcomes. Says Kaufman, “We’re going to save 50,000 lives every year just in the U.S.”

David Essex is a freelance science writer based in Peterborough, nh.

Computer Graphics
Catmull Wins Second Oscar

acm fellow ed catmull, a computer scientist, co-founder of Pixar animation Studios, and president of Walt disney and Pixar animation Studios, received the Gordon e. Sawyer award from the academy of motion Picture arts and Sciences in recognition of his lifetime of technical contributions and leadership in the field of computer graphics for the motion-picture industry. catmull was presented with an oscar statuette at the Scientific and technical awards Presentations last february at the beverly Wilshire hotel.

“ed is one of the rare individuals who can bridge the space between science and art,” said academy President Sid Ganis. “his vision, ingenuity, and groundbreaking designs have made the impossible

possible—for filmmakers and
movie audiences around the
world.”
catmull, who delivered a
keynote address at SiGGraPh
2008, has described acm
SiGGraPh as his “home
community.” he is regarded as
an innovator by the community
for his key contributions to
fundamental computer graphics
concepts like z-buffer and sub-
division surfaces, and has held
several leadership positions in
SiGGraPh over three decades.
in 1995, catmull became an
acm fellow, and was cited
for “his many and noteworthy
advances in computer graphics
as an individual researcher, as an
inspiring leader in the field, as a
director of organizations, and as
a mentor for many.”
in the course of his career,

18 communicAtionS of the Acm | APriL 2009 | voL. 52 | no. 4

catmull founded the computer graphics laboratory at the new york institute of technology as well as the computer division of lucasfilm ltd., and Pixar animation Studios.

in 2000, catmull and his team received an oscar for an academy award of merit for their significant advancements to the field of motion picture rendering as illustrated in Pixar’s RenderMan. he previously received two Scientific and engineering awards from the academy. in 1992, he was part of a team recognized for the development of RenderMan software. in 1995, he was on a team honored for pioneering inventions in digital image compositing. he also shared a technical achievement award from the academy in 2005.