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.


SLICE OVERLOAD

"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 or reading the study. Suddenly, in the fact that you can non-invasively get coronary artery angiography, the radiologists see this as an opportunity to now do that sort of imaging on cardiology patients. The cardiologists are either going to have to accept the modality and learn how to read it and own it themselves, or they are going to be referring their patients to radiologists."

"There is really a performance trajectory that is only going to get better from a patient's point of view," Newton opines. "It's going to be possible very soon to do non-invasive imaging of the coronary arteries and it will no longer be necessary to poke people in the leg and do it invasively like we are doing now. And this is all going to be driven by 3D. The technology is creating alternatives to the traditional means of making a diagnosis."


IN THE DRIVER'S SEAT

Quantum Radiology Northwest is a radiology group in Georgia consisting of 33 physicians servicing three hospitals in the Well Star Health System (Tennastone Hospital, Cobb Hospital and Caulding Hospital). In addition to the hospitals, the group services nine imaging centers scattered throughout the area. Quantum Radiology produces its own studies on 4-, 6-, and 10-slice scanners and the facility receives electronic MR and CT images from partnering clinics over the Internet. Using a number of high-end workstations, including Vital Images' Vitrea 2, they render the large amounts of data sets into 3D images.

"Any still pictures that are made can be uploaded using the DICOM standard in our own PACS," says Jay Cinnamon, MD, neuroradiologist at Quantum Radiology. "Outside clinicians also can go on the PACS and pull up the images themselves. The workstations have their own IP address so in theory we can pull up a report on that IP website. We can't upload any movie because there is no DICOM standard for uploading a movie. These are usually saved on a CD for the patients."

"All the workstations cost in the range of $100,000 to $200,000, depending on the options you want to have," explains Cinnamon. "Sometimes the workstations come as a package deal when you buy a CT machine. But, comparing prices, no CT manufacturer is going to jeopardize the $1.3 million sale. If you say you want their scanner but a different workstation, they will be accommodating. Not all radiologists know that they can ask for this and end up buying the manufacturers' workstation because that is what they presume they have to do. The buyer is in the driver seat," contends Cinnamon.


3D IN FLIGHT

Joel Bortz, FRCR, COO of Health Scan Imaging in Palm Desert, Calif., says that his piece of mind is worth more than the money that was spent on the facility's 3D workstations. "We use 3D a tremendous amount for all of our spinal work, for all angiography if we are looking for aneurysms of the abdominal aorta, blockages of the carotid artery or blockages of the peripheral vessels to the leg as well as aneurysms of the thoracic aorta," says Bortz. "We can do 3D imaging to see where the aneurysm is, but we also can do fly-throughs inside the vessel to measure it. It is also an important tool for orthopedics."

Although Health Scan Imaging is a free-standing imaging center, Bortz says vascular surgeons from Eisenhower Hospital, a 239-bed facility in Rancho Mirage, use the clinic because of its 3D capabilities. The facility is equipped with TeraRecon's AquariusNET workstation and Viatronix Inc.'s V3D Colon.

Since its opening, the clinic has performed 535 virtual colonoscopy studies. "If you asked me how many I did in the last month, I would say four. A year ago, we were performing 45 a month. Ask me why? I really don't know. But I do know that now that the literature and press is there, it is going to be the No. 1 screening test," say Bortz.

Virtual colonoscopy has stolen a bit of the spotlight lately. Researchers recently presented at the 2003 Radiological Society of North America meeting that 3D CT colonography is more sensitive and less invasive than conventional colonoscopy in screening average-risk patients. "But, it is an out-of-the pocket expense," says Bortz. "Health Scan charges its patients $650 per exam. When I worked in Los Angeles, we were charging $1,250."

"You can not do this study on a single-slice scanner because it does not cut it thin enough," says Bortz. "The minimum requirement is a 4-slice scanner and the optimum is a 16-slice scanner. You need to get 500 slices while the patient is on their back and 500 while the patient is lying on their stomach - each is one millimeter thin. It takes us 25 seconds of breathhold to do each. The Viatronix software then takes about nine minutes to reconstruct the images."

Then the fun begins. "You push the button and you start to fly-through," says Bortz. "If you come across something suspicious like a polyp or a tumor, you stop the fly-through and immediately go to your 2D pictures on the same monitor - but you usually have made your diagnosis on your virtual fly-through."

Locating benign growths in the colon may become easier with the addition of computer-aided detection (CAD) to virtual colonography. Viatronix is currently working with CAD companies, including iCAD Inc., to integrate CAD into the user interface for colon and lung screening exams. Stay tuned.


A NEW ERA

Another advantage of 3D is more targeted radiation therapy, thus minimizing the damage of healthy tissues surrounding the treatment area. When Elekta Inc. installed one of its four Synergy radiotherapy treatment systems at William Beaumont Hospital in Royal Oak, Mich., in early 2003, the physicians were already well-trained in using 3D volumetric imaging in radiotherapy. For the past 10 years, the facility had been involved in the process of developing a treatment system that integrated 3D imaging tools to target cancer tumors.

John Wong, PhD, director of clinical physics at the Department of Radiation Oncology at Beaumont, and his team of colleagues sought to solve the problems plaguing modern radiotherapy, including internal organ motion and errors in patient set-up. They developed a device that eventually became Elekta's FDA-approved (October 2003) Synergy by combining the x-ray scanning volume and treatment processes to give a 'real-time' 3D indication of the cancer tumor location during treatment.

"One of the unique things of Synergy is that we make use of cone beam CT," Wong says. "The detector itself is not the usual slice beam detector of CT scanners. The detector produces 256 slices of high-resolution images that are rendered into 3D images while the patient remains in the treatment position. "Just before treatment, we acquire the volume CT data of the patient and then we guide our placement beam - within minutes," continues Wong.

Pre-treatment imaging of a tumor can now be performed immediately prior to treatment. "If you look at the history of radiation therapy, we have gone from 3D conformal radiation therapy 10 years ago, to an era of IMRT [intensity modulated radiation therapy] and what we are seeing now is an era of IGRT [image-guided radiation therapy]," says Wong.

Breaking Even: Business Feasibility of 3D Reconstruction

In the past five years, the 3D Imaging Service at Massachusetts General Hospital has expanded from a staff of four people performing one exam daily to a staff of 13 people performing 80 exams daily. "Twenty are 3D ultrasound, and 60 are CT and MR. Out of those, at least 40 to 45 are CTA [computed tomography angiography] and MRA [magnetic resonance angiography] exams," says Gordon J. Harris, PhD, director of MGH's 3D Imaging Service and associate professor of radiology at Harvard Medical School.

"There are a lot of financial and technical details involved with setting up a clinical 3D service," Harris says. "You need to work on the scheduling, billing, PACS routing, all of the infrastructure so that the 3D exams get completed, finalized and billed properly. You also need to work closely with the compliance people to make sure that the procedures and protocols set up are appropriate in terms of Medicare compliance issues."

Breaking even after three years, Harris witnessed the business grow into a profiting organization. That is, until 3D reconstruction was eventually included as part of the CTA and MRA CPT billing code. Prior to that, the 3D reconstructions for CTA and MRA could be billed separately. Insurance reimbursement is an important factor in developing a profiting clinical 3D Service, says Harris. "This created complications and confusion because only the base exam was reimbursed, although two exams were really being performed," explains Harris.

A separate APC (ambulatory payment classification) code has been added for 2003-2004, but problems still exist. More than half of the hospitals are charging less for a CTA than for a CT exam. "What ends up happening is that the CMS [Centers for Medicare & Medicaid Service] ends up calculating a low cost for CTA relative to CT. The differential between the two exams now is only $5 for 2003. It's gone up a little bit in 2004, but we are trying to educate the hospitals now in conjunction with other organizations that if you are charging less for a CTA than for a CT, that is deflating the reimbursement for CTA relative for CT. It makes it harder to cost-justify doing 3D for CTA if there is nothing to pay for the added work, staff and equipment," explains Harris.

3D + PACS = Better Images and Workflow

It is not economically viable for healthcare institutions to distribute high-end 3D workstations throughout the enterprise, but it is affordable to provide clinicians with thin-client workstations via PACS.

As a result, PACS vendors have been scurrying to combine their powers with 3D capabilities. Requiring no additional hardware, Voxar's Plug n View is a popular choice for PACS vendors, as seen in its integration with more than 20 companies, including Fujifilm Medical System's Synapse PACS. Voxar's most recent collaboration, announced at RSNA, will now combine Voxar 3D with Agfa Healthcare's IMPAX PACS.

TeraRecon recently launched an initiative to integrate GE Medical Systems' Centricity PACS with its AquariusNET offering. In March 2003, Viatronix announced the integration of its V3D-Colon and V3D-Explorer packages with Sectra Imtec AB's PACS through their Clinical Solutions Network. This allows seamless flow between reading studies on the Viatronix systems and storing them on Sectra PACS. Vital Images began integrating its 3D software with McKesson Information Solutions in July 2003. Vital Images also recently signed an agreement to acquire HInnovation Inc. with intent to sell its thin-client 3D imaging system, iConnection. HInnovation provides software solutions that enable physicians to use PCs or notebooks to access 2D, 3D and 4D medical imaging applications securely over the Internet.