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| Thanks to 64-slice CT angiograms, Jeff Schussler, MD, and his colleagues at the Baylor University Medical Center are ahead of the cardiac curve. |
Jeff Schussler, MD, felt like someone who had just received the greatest gift of his life, and, of course, he couldn’t wait to test it out. But when he opened the package, there were no instructions, no one to call for help, no reference books, and no guidance along the way.
These were the problems that Schussler?a cardiologist at Baylor University Medical Center’s Jack and Jane Hamilton Heart and Vascular Hospital (Dallas)?and his colleagues faced when they were introduced to the GE LightSpeed 16-slice CT scanner that could be used to detect coronary heart disease without the need for invasive catheterizations. The possibilities were endless. But the trouble was, no one knew how to interpret the scanned data.
All that the physicians had at their disposal was patience, perseverance, and a strong desire to take this medical marvel and learn how it worked from the ground up.
“The problem was that nobody knew how to read the scans,” Schussler admits. “When we acquired the original 16-slice CT scanner, it was considered new technology. Not a lot of people were considered experts in the field, because few people had had enough experience with it.
“That’s still true today [with our 64-slice scanner],” he adds. “But imagine three years ago, when there were maybe 15 to 20 scanners in the country. Maybe three people in the country, and no one in our area, even knew what they were talking about when it came to CT and coronary angiography. So we kind of had to beat our own path.”
The Study
Necessity proved to be the mother of invention for a group of Baylor cardiologists and radiologists. With no frame of reference to fall back on, the group decided to create one of their own?case by case, scan by scan?starting with a study of 50 patients already scheduled to receive invasive catheterizations for “appropriate” reasons, according to Schussler.
In late 2003 through mid-2004, Baylor offered the patients a “free” CT scan. Physicians explained to patients that although the results could not be used in their cases, and although there were minor risks involved, the study would go a long way toward alleviating the need for invasive catheterization in a new generation of patients. Many of the patients agreed to undergo two angiograms?one using the traditional method, one with the new CT scanner.
After performing the scheduled invasive catheterizations, the physicians compared what they found using the traditional method with what it saw on the CT angiograms. The conclusions were both exciting and frustrating.
“We had a gold standard; we knew how to read and interpret invasive angiograms. The problem was converting that knowledge to the CT scan,” Schussler says. “It was frustrating at times because of the speed it took us to read one of those angiograms. For a lot of us who came from the cath lab, we said, ?Okay, I can read a cath, so it should take no time to jump over and do CT.’ Well, it’s not true. I can do a diagnostic invasive angiogram in about ten minutes; to read a CT scan for the first time, it would take us an hour and a half just to figure out what we were looking at.”
At the same time, the Baylor physicians realized they stood at the threshold of a coronary medical breakthrough, one that could dramatically reduce the number of invasive catheterizations performed each year.
According to Schussler, more than 3.5 million invasive catheterizations were performed in 2004 in the United States, each carrying a cost of between $8,000 and $14,000. That’s two to three times more than what the typical CT angiogram costs, Schussler says.
“We did reads on a number of cases,” Schussler notes, “and probably after the 30th case, we started to get the idea of what we were looking at. Once we did the invasive catheterizations, we’d sit down as a group, discuss, and ask questions: ?Were we right over here? Were we wrong over there? Why did we miss this?’ It was exciting to be on the cutting edge of this technology. All of us that are participating realize that this is going to be a really big change for cardiology in general over the next few years.”
The comparison of the invasive cardiac caths with the new, noninvasive angiograms was instrumental in the training for those physicians interested in this new technology.
The Technology
When GE Healthcare (Waukesha, Wis) introduced its latest 64-slice channel CT scanner at RSNA 2004, the physicians at Baylor knew that at the cutting edge was the only place to be.
“We had a good relationship with GE in other areas in the past?in the cath lab and some radiology departments?and so when we wanted to make the leap to this newer technology, it was a natural choice,” Schussler says. “GE came to us with good terms, and they exhibited good service in the past. That was the driving force. We wanted to be on top of the curve, if not ahead of the curve.”
The GE Healthcare’s LightSpeed VCT helps physicians capture images of the heart and coronary arteries in just five heartbeats?something no other CT system can offer. In a single rotation, the LightSpeed VCT creates 64 submillimeter images, totaling 40 mm of anatomical coverage, which can be combined to form a 3-D view of the patient’s anatomy for the physicians to analyze.
“The LightSpeed VCT allows acquisition of cardiac images in a very short span of time,” explains Schussler, whose hospital purchased the 16-slice scanner 3 years ago and upgraded to the 64-slice scanner in May 2005. “Now, we have a scanner that is very quick, accurate, and easy on the patient. The drawbacks are that there is radiation, albeit a small amount. But the aspects that make
64-slice scanners ideal are their ease of use, the speed at which they acquire images, and their accuracy.” The total throughput time for a patient in the department is less than 1 hour, but the actual scan takes just 5 seconds.
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| This 64-slice coronary CT angiogram?captured with the GE Healthcare LightSpeed VCT at Baylor University Medical Center?demonstrates normal coronary and cardiac anatomy in a 46-year-old male patient. The full 3-D heart is shown in panel A; in panel B, the larger structures of the heart have been removed so that the coronary anatomy is able to be seen by itself. |
The Future
Physicians still face a steep learning curve with scanners like the LightSpeed VCT. “As a group, I know we learn something new almost every time we read a scan,” Schussler says. But the heartening news is that those physicians who follow in the footsteps of the trailblazing group at Baylor have plenty of information on which to fall back. Available today is a plethora of information in the form of training courses, textbooks, and various papers that can be found on the Internet?a very different situation than when Schussler and his colleagues first started using CT angiograms.
“This is a pretty big paradigm shift for cardiology,” Schussler admits. “These types of things don’t come around that often?when you see something so brand-new and so revolutionary that is really going to change how we practice cardiology. And it’s going to do it in a relatively short time.
“So, we are seeing the changes that, in a few years, will determine how people decide what tests to order,” he adds. “Over the next decade, this type of scan will take the place of many of the older tests that have served us well over the years but might be superceded by this new technology.”
Dave Cater is a contributing writer for Medical Imaging.
