The world of mulitidetector computed tomography (CT) changed dramatically when systems leaped quickly from four to 16 slices and then to 64 slices just a few years ago. The call for more slices and better images was answered, providing diagnostic opportunities not previously available. Now the question being asked is — What’s next? Executives from GE Healthcare, Philips Medical Systems, Siemens Medical Solutions, and Toshiba America Medical Systems, as well as radiologists, offer their perspective on the future of CT.
Careful not to show their hands, vendors talk in generalities regarding the direction in which CT is headed. All agree there is more that can be done in terms of image quality and speed, and they want to be among the major players unlocking the door to earlier detection of disease. They believe that how disease is detected earlier could rest in multidetector CT scans. In short, with an eye on tomorrow, the CT scanner replaces the physical exam.
The backbone of CT
For facilities that got caught in the quick-paced revolution of multidetector CT and now wonder if they will be stuck with an outdated 64-slice scanner in just a few years, consensus says relax — 64-slice scanners are not going away anytime soon. Today, approximately a quarter of healthcare facilities across the country are using 64 slice. In 2006, the market saw a remarkable growth of 87 percent over the previous year.
Even with Toshiba’s 256-slice CT scanner in clinical trials and other 128- and 256-slice CTs being developed, the 64-slice scanner will continue to be the backbone of CT imaging. What will change are add-ons that make the scanner a more specific diagnostic tool along clinical pathways and improvements in workflow.
Currently, the most advanced 64-slice CTs on the market include: GE Healthcare’s LightSpeed VCT; Phillips Medical Systems’ Brilliance 64; Siemens Medical Solutions’ Somatom Sensation 64 and Somatom Definition dual-source CT scanner; and Toshiba America Medical Systems’ Aquilion 64. Each of the vendors has launched newer versions or upgrades since their initial introductions in 2004 and 2005.
What’s on the horizon
As much as has been done in the world of CT, what’s on the horizon promises to take this modality to the next level. And it’s not just about adding more slices, but rather addressing the larger issues of diagnosing disease earlier, adding clinical value, making scans safer for the patient, managing workflow, and increasing efficiency. Look for yearly introductions of software and other products from the vendors to answer the call.
- More slices. Though only Toshiba has been talking publicly about its 256-slice prototype (now having logged two installs worldwide, one in Tokyo at the National Cancer Center and the other for a three-month study at Johns Hopkins University School of Medicine in Baltimore, Md., that ended in April), other vendors say they also are exploring more slices, including a 128-slice scanner, though they would not confirm the exact nature of their testing. Doubling and quadrupling the number of slices mean thinner slices, more coverage, faster rotation, less radiation and a lower contrast dose — and of course, more stellar image quality.
- Clearer images. Distinguishing subtle differences or seeing new areas of anatomy will continue to improve with advanced visualization software upgrades. 4D images, moving 3D images, will be useful tools.
- Added diagnostic value. Scans of the future will provide more and better information before someone suffers a stroke, has a heart attack, or is in a later stage of cancer. The new information will be used in preventive medicine in addition to determining treatment of an existing condition.
- Adapting to body movement. Capturing the heart between beats and mid-beat — essentially freezing its motion — will provide a look at vital heart anatomy at its most vital, yet still point.
- Clinical pathways. Instead of thinking of the number of slices a CT scanner creates, scanners will be thought of more in terms of clinical pathways — cardiac, neuro, liver, colon and whole body. More software will be developed to address criteria specific to visualizing each of these areas.
- More automation. Preset criteria for scans and for image processing and post-processing will continue to be refined. The work of a technologist will be streamlined as data input will match predetermined criteria to provide the best position, dose and image quality. Automation will continue through the processing and delivery of select images, providing the most relevant information.
- Working out the flow. Orchestrating the CT scan workflow process from the time patient information is registered to the time a scan is read and the report sent will develop to become more like other modalities that easily track every stage. Look for more tools to help in the process and the ability to read scans remotely.
- Image management. CT files have gotten much bigger over the years, from 200 to 300 images to 2,000 to 3,000 images and even upwards of 8,000 per study. Whittling down the number of images a physician reads will be more important. More CAD programs will automatically filter images and point out patterns, changes and spots for the trained eye of a clinician.
- Stewards of radiation dose. Controlling the amount of radiation a patient receives will be a strong marker in the future advances in the CT arena. Today software programs such as GE’s SnapShot Pulse technology reduce a patient’s radiation exposure up to 70 percent. Still, as CT systems are refined, more ways will emerge to control radiation dose while ensuring excellent image quality.
Today’s system for tomorrow
If you currently have a 64-slice CT scanner, look for upgrades to maximize its use. If you are in the market for one, go ahead and purchase one of the current systems — they will provide plenty of horsepower into the future. There is no need to hold off for more slices as vendors continue to provide enhancements to the current systems.
|Toshiba’s 256-slice CT scanner: The Future is Almost Here|
|When it comes to adding more slices to CT, Toshiba America Medical Systems is one vendor offering a view into the crystal ball. Clinical trials of its 256-slice CT beta prototype — the Aquilion 256, which the vendor calls “the next revolution” — have been a worldwide event. Testing has been underway since 2002 in Tokyo, Japan, at the National Cancer Center. More recently, Johns Hopkins University School of Medicine in Baltimore, Md., deployed the two-metric-ton device for a three-month study until mid-April.|
João Lima, MD, director, cardiovascular CT program, and associate professor of medicine and radiology, led the cardiovascular testing during the Johns Hopkins trial. Working with Lima was Richard George, MD, senior post doctoral fellow of cardiac imaging and assistant professor, who says that the main objective “was to develop protocols and methods for combining CT angiography and CT perfusion imaging.”
Overseeing neurological testing was Kiernan Murphy, MD, director of interventional neuroradiology and associate professor. At Johns Hopkins, they perform 4,500 neuro exams a year using 4-, 16- and 64-slice CT systems made by Toshiba and Siemens Medical Solutions. Murphy says the 256-slice CT trial provided an opportunity to use whole-head perfusion imaging scans to identify slowed blood flow areas in the brain that are vulnerable to stroke before a stroke actually happens.
Offering four times the coverage of 64-slice CT, 256-slice has the ability to image in one rotation 13 centimeters (approximately 5 inches) of a heart in one beat, or the brain, entire joints, most of the lungs and liver. By contrast, 64-slice covers 3.2 cm per image and requires several rotations to scan an organ. The 256-slice scanner provides 0.5 mm slices from its helical scan that are reconstructed in 3D using Vital Images’ Vitrea advanced visualization software. During the Johns Hopkins study, they noted a decrease in radiation dose to 25 percent of that of a 64-slice scan. The scan time goes down substantially as well — with a brain scan taking 1 second from 4 to 5 seconds previously, and full coverage of the heart in 1 to 2 seconds compared with 8 to 10 seconds with 64-slice. The faster scan times and greater coverage also lower the contrast dose.
Improved images, faster speed, lower radiation and contrast dose on the 256-slice CT, but are more slices better? The answer is only if the slices provide more and different information. For instance, Johns Hopkins looked at calcium scores that detect hardening of the arteries and ways to measure blood flow decreases attributed to partial blockages, something the 64-slice scanner has been unable to do. They also were able to capture the scan of a heart with an irregular heartbeat. This type of clinical information is what makes the larger scanner a more useful diagnostic tool.
A major challenge that remains is how to manage all the images, as many as 5,000 for one cardiac or brain study, while higher resolution neuro studies can surpass 10,000 images. To handle that, Toshiba is developing an image-review technology to prescreen images, reduce the number to be reviewed by clinicians, and even point out areas of interest to be read. Along with more slices and information will come a hefty price tag of more than $2 million once the 256-slice CT scanner has FDA 501(k) clearance, which is expected sometime in 2008. Stay tuned.