The clinical world of three-dimensional (3D) imaging is expanding. With the advent of multislice CT scanners and faster MRI studies, medical imaging professionals everywhere are increasingly relying on computer-created volumetric images for better diagnosis, treatment and non-invasive surgical planning. Everyone is getting a piece of the 3D pie - from radiologists, cardiologists, clinicians, technologists, radiation therapists and surgeons. Even many once-reluctant physicians are finding they cannot resist integrating and using the (easier to use!) 3D tools offered today. It's a busy, image intensive world; 3D imaging is offering a way to cope.
"In the past, doctors typically had few problems interpreting small slice studies," says Steve Sandy, vice president of marketing at 3D software-maker TeraRecon Inc. "When you were only generating a few slices on a single-slice CT, they were quite easy to look at. And the concept was single best, so everybody tried to find the single best study that depicted the pathology and provided the results.
Looking at two-dimensional (2D), black and white, axial images - and a lot of them - soon became inefficient, and down-right impossible with the introduction of multislice scanners. Sophisticated tools such as 3D volumetric imaging, MIP (maximum intensity projection), MPR (multi-planar reformat) and surface shading developed to help radiologists successfully handle mass amounts of data produced by these advanced machines.
Its applicability in various regions of medical imaging has fueled 3D's market numbers. Frost & Sullivan estimated that the total U.S. 3D imaging market earned approximately $400 million in 2002, with an annual growth rate of 23 percent. Of that, approximately 60 to 65 percent of the revenues were generated by 3D imaging hardware and software products for CT and MR, and the remaining percentage was attributed to 3D ultrasound. The San Jose, Calif.-based research firm estimates the market will continue to soar in the future, reaching $1 billion over the next five years as the necessity for 3D tools grows in parallel with technological advances in the modalities.
Two major applications benefiting from both CT multislice scanners and 3D imaging are CTA (computed tomography angiography) and MRA (magnetic resonance angiography). Additionally, ECRI (Plymouth Meeting, Pa.) recently predicated that the utilization of noninvasive CTA will increase rapidly over the next five years. ECRI forecasts that multislice CTA will be performed more frequently as a complement or replacement for other cardiac examinations, such as diagnostic cardiac catheterization, MRI and nuclear imaging.
HEART OF THE MATTER
Carter Newton, MD, cardiovascular CT imaging consultant, reads from his home office in Tucson, Ariz., about 20 CT coronary angiography exams weekly that are sent from South Carolina Heart Center (SCHC) in Columbia, S.C. Newton and SCHC are early adopters of this technology that uses high-resolution CT images of the heart and 3D workstations to see in greater detail not only the blood vessels, but also smaller moving parts, such as coronary arteries.
"It takes about 15 to 25 seconds to acquire the image on the machine," says Newton. "You take that raw CT data and you reconstruct the series of slices (about 250) and that makes the 3D volume. That takes about a minute. Now you are in possession of the volume in one cardiac phase."
The technologist then burns the images on a CD in a DICOM format and over-nights them to Newton (SCHC and Newton are working on setting up an Internet link for direct file transfer). "Once its loaded on my workstation [TeraRecon's AquariusNET], it's a matter of using the software tools the workstation provides me with to slice, analyze and colorize the images so that I can study the volume content in a medieval way to make a diagnosis," explains Newton.
As of now, the exams are paid for under the general CPT code for chest angiography, although Newton is looking at blood vessels and coronary arteries. "What does not exist is a CT code for looking at coronary arteries. Third-party payers are not yet sure that the test is good enough to do it all across the board," explains Newton.
Reimbursement issues are not the only obstacle in the way of this procedure. "Cardiovascular imaging now is suddenly something that can be done with high-resolution CT scans," says Newton. "Cardiologists have never participated in CT imaging - performing the study