Bringing 64-Slice CT Imaging Technology To The Table.
03/22/2006.
Cardiology Associates’ new G.E. CT scanner delivers incredibly sharp, three-dimensional views of the heart and arteries in seconds. In a single rotation, the LightSpeed VCT scanner produces 64 high-resolution images which are combined to form a 3-D view of a patient’s heart and entire coronary tree. Our cardiologists now can survey the motion and pumping action of the heart in detail to noninvasively identify blockages and more quickly and accurately diagnose cardiovascular disease.
The Evolution of the CT Scan
Noninvasive imaging technologies have long held tremendous promise in the area of cardiovascular diagnostics. Since their introduction in the early 1990s, the first multi-slice scanners have steady evolved. The 4-slice scanner hit the market in 1998 and represented a major breakthrough in clarity and functionality. Soon thereafter, 16-slice scanners were rolled out which further reduced scan time and artifacts caused by movement and ultimately the time patients were required to hold their breath during the procedure. Still image quality was lacking.
Enter the 64-slice CT scanner, a quantum leap forward in image clarity and quality. Scan times are now on the order of several seconds, which means even patients with severe pulmonary disease and congestive heart failure are capable of holding their breath for the required length of time. Rotation speed of the scanner gantry is now down to less than 0.5 seconds per rotation. 0.35 seconds per rotation with CANM’s new G.E. LightSpeed VCT. What’s more, with the number of “slices” has multiplied exponentially and, as a result, higher resolution images afford extremely high accuracy and detail. Individual plaques can be detected and characterized. Calcification can be visualized and used as an added variable in disease management.
Who is an ideal candidate for Cardiac CT?
- Equivocal functional study…ETT, stress nuclear, stress echo
- Chest pain with intermediate probability of coronary artery disease
- Patients scheduled for non-coronary cardiac surgery (myxoma, asd) with need to know coronary anatomy
- Suspected coronary anomaly
- Patients with a slow, regular heart rate
Who may be a candidate for a Cardiac CTA?
- Symptomatic patients with intermediate to high probability of cad (without preceding functional study)
- Symptomatic patients post stenting (only after a functional study)
- Symptomatic patients post CABG (only after a functional study)
Who is not a candidate for Cardiac CT?
Patients who:
- present an irregular heartbeat (atrial fib, etc.)
- are allergic to iodinated contrast
- cannot receive a beta blocker due to asthma, etc.
- are unable to get a heart rate less than 65 bpm, even with po and iv beta blocker
- have a renal insufficiency
- cannot tolerate a 10 to 15 second breath hold
- are pregnant
Who may not be a good candidate for a Cardiac CTA?
- Asymptomatic patients
- Patients who want to have a CTA to see what’s there
The following may make the interpretation of a Coronary CTA difficult:
- High coronary calcium score may cause “blooming”
- Stents may cause “blooming”
- Cardiac devices, metallic clips, lima grafts or proximal anastomosis may cause “blooming”
- Previous CABG
- Higher heart rates or patient movement
- Obese Patients
Take Home Points on the Cardiac CT/CTA:
- A coronary CTA is most helpful in its negative predictive value — normal is normal!
- A coronary CTA provides basically qualitative assessment of atherosclerotic plaque. It does not have the spatial resolution of standard coronary arteriography.
- Cardiac CTA exposes the patient to 2 times as much radiation as standard cardiac catheterization.
- Coronary CTA has not replaced standard cardiac catheterization.
- Coronary CTA will reduce the number of normal cardiac catheterization currently being performed.
- Coronary CTA is another anatomic test, not a physiologic test.