Fishman urges radiologists to capitalize on 64-slice capabilities

November 27, 2005

There’s a reason why Dr. Elliot K. Fishman has had years of success in pushing the limits of diagnostic imaging. He is cool under fire.

There's a reason why Dr. Elliot K. Fishman has had years of success in pushing the limits of diagnostic imaging. He is cool under fire.

During Sunday's opening session, Fishman, director of diagnostic radiology and body CT at Johns Hopkins, attempted to discuss the advantages of 64-slice CT. The problem was that his slides didn't project onto the large screens in the Arie Crown Theatre. Several people, including moderator Dr. Gerald D. Dodd, disappeared behind a curtain to fix the glitch.

Fishman proceeded to quote Leonardo Da Vinci ("Simplicity is the ultimate sophistication"), to tell the audience that 16 slices are not enough, and encourage radiologists to talk about CT "volume," rather than "slices."

In between interruptions by Dodd, who provided periodic updates on the progress of the fix, Fishman said that radiologists talk of temporal resolution, spatial resolution, and scanning parameters. But now they must speak of patient parameters. The ultimate goal of any technological advance is to provide better patient care.

"The number of detectors alone doesn't determine quality, and the number of slices doesn't necessarily mean a better diagnosis," he said. "It all boils down to the ability to detect disease. With the new 64-slice scanners, this means using the right protocols and, more importantly, the correct postprocessing tools to enhance visualization."

Dodd appeared again, this time taking Fishman's computer behind the curtain.

Without his slides, Fishman quipped, "I always wondered what it felt like to be Eric Clapton without a guitar ... and without the ability to sing a single note."

Within seconds, the problem was fixed and Fishman sang his song of advanced imaging to a packed house.

Having the technology is not enough, he said. Radiologists must use it the way it was intended. Many owners of 64-slice scanners continue to use the same protocols from their 16-slice days. The challenge for the RSNA is to train radiologists to use their equipment appropriately.

A problem with that challenge, Fishman admitted, is that radiologists have little time to keep up with every new technological advancement.

Radiologists are not just dealing with information, but with information transfer, Fishman said. Visualizing disease with the postprocessing techniques afforded by isotropic imaging requires large amounts of data. Radiologists must find ways to present that information in a simple fashion to referring physicians so there is an increased understanding of the pathology.

"Thousands of slices don't make for a better diagnosis. In fact, there's more chance of a mistake," he said.

Some areas where 64-slice imaging and its attendant postprocessing have benefit include virtual colonoscopy, virtual bronchoscopy in the airways, and CT angiography. The latter is the fastest-growing procedure at Johns Hopkins, increasing 40% per year.

Fishman gave examples of pathology that would never be seen on axial views but can be easily identified on 3D volume-rendered MPRs. Skin, muscle, bone, and blood vessels can be seen, all at once or in any combination. He encouraged radiologists to use these tools interactively to better detect disease.

In virtual colonoscopy, new techniques accentuate mucosa, which then can be segmented and visualized in different perspectives. Software allows radiologists to go beyond the colon, to the stomach, and look for gastric polyps as well.

"You can see 2-mm structures that you can't appreciate on axial images," he said.

New CT perfusion techniques help visualize tumors earlier, show the extent of tumor infiltration, and define tumor angiogenesis, all of which go toward providing better patient management. For Crohn's disease, 3D volume visualization can show increased vascularity in thickened valve nodes well under 1 mm in size. That's not even possible with 16-slice CT, Fishman said.

Cardiac CT imaging can be performed with 16-slice scanners, but 64 slices make it a routine application including visualizing the vascularity of a carcinoid tumor or characterizing soft plaque. There are tools to segment out the vessels, lay them out in the correct orientation, and go inside them as well.

CT urograms can be created with the early and later phase imaging, thus providing nephrologists with all the information they need to perform a nephrectomy. The carotids can be isolated automatically and a study finished in less than five minutes.

"I've met many people who are not willing to do the 3D processing, but it's easy, and it's important for better patient care," he said.

For pediatric patients, the dose can be lowered and a heart scan completed in 1.5 seconds. There are many tools to interactively visualize the chambers and vessels, either static or rotating - or even the beating heart.

But all these tools mean nothing if radiologists are not using them. Only about 20% of MSCT owners take advantage of such techniques.

"Simply buying a new scanner isn't good enough. If used correctly, it can be both evolutionary and revolutionary," he said.