|Cardiac CTA volume reconstruction on the TeraRecon Aquarius workstation highlights the coronary vessels.|
Advanced visualization has shot from the realm of experimental, futuristic technology to almost routine practice in just a few short years. While the reliance by physicians on 3D varies, clinicians can often determine the presence and extent of heart disease without an invasive procedure. On the horizon, 3D users see further improvements that will reduce radiation exposure and speedier interpretation times.
"Over the past two to three years, 3D post-processing has gone from something we kind of played with to something that has been incorporated into the general management of patients with cardiovascular conditions,” says David Bush, MD, director of the cardiac catheterization lab at Johns Hopkins Bayview Medical Center in Baltimore, Md.
Bush has been using Vitrea workstations and VitalCardia software from Vital Images since 2003. The technology helps him provide a conclusive answer about the extent of coronary disease in patients. For patients who are younger or who otherwise fall outside the typical risk group for coronary disease, they are great candidates for cardiac CT. “The expectation is that they’re not going to have much disease and if you can confirm that, you’ve saved them an invasive test.”
“Cardiac CT is relatively new. Not that many cardiologists do it because you are required to have very sophisticated software to read coronary CT angiograms. It puts a lot of demand on software,” says John Lesser, MD, cardiologist at the Minneapolis Heart Institute/Abbott Northwestern Hospital in Minnesota. He has been using Vitrea workstations and VitalCardia software since venturing into cardiac CT in 2003.
VitalCardia lets Lesser read studies more quickly and accurately. He finds 3D cardiac imaging particularly helpful when treating peripheral vascular disease and complicated congenital heart disease.
Carter Newton, MD, a cardiologist at the University of Arizona in Tucson is another early adopter of 3D imaging. He uses TeraRecon’s Aquarius workstation and AquariusNET server for his monthly CT reading and reporting classes for radiologists and cardiologists.
Better than surgical dissection
3D imaging allows for both static and moving images. “The use of static images rendered without motion artifact is extremely useful for high resolution coronary artery analysis,” he says. “That’s really the thing that turns everybody on.”
This high resolution structural imagery allows for study of the various elements, including arteries, veins, valves and other various heart structures. “You can actually visualize the heart in a ‘virtual’ anatomic presentation than in an actual surgical dissection,” says Newton. Users also can control how brilliantly the tissues are rendered and emphasize cardiac structures that are the subject of inquiry: ventricular muscle and pulmonary vein connection, for example.
Dynamic images let clinicians watch phases of the heart cycle come together in repetitive action. Cine, or 4D, imaging lets clinicians add time and view via animation. “We can watch the beating heart from any angle and detect even subtle variations from the norm. Wall motion, valvular motion and other complex elements of the cardiac cycle are observed in detail. The ventricular performance parameters are easily measured,” he says. This information, in addition to coronary artery analysis, is key to an accurate diagnosis and treatment plan. 3D advanced visualization tools also let cardiologists isolate sections of the heart: particular chambers or particular arteries.
These segmentation tools, evoked with a simple click of a mouse button isolate a particular structure for analysis and as such are big time savers, Newton says. “You may only be looking at 5 percent of the total information in the scan, but it’s the information relevant to your inquiry,” says Newton. “It speeds and simplifies the analysis.” The volumetric detail of a heart scan also can be merged with information obtained from another modality, such as electrophysiologic details of electrical pathways in patients with heart rhythm disorders. The fused information can help plan and guide a surgical or transcatheter intervention.
Accuracy and speed
Lesser has learned the value of 3D software in helping with accuracy and speed in coronary CT. “When you’re a cardiologist, you don’t have much familiarity with software in this regard, so cardiologists may not understand