Key Specifications for CT Cardiac Imaging
Here is a list of some key technologies that should be considered when evaluating new CT scanners for cardiac imaging.
1. Speed — The faster the temporal resolution a scanner has, the faster its gantry can rotate around a patient. Some of the newest scanners move fast enough to capture images that freeze cardiac motion and prevent motion blur or the need to stitch images from several heartbeats to reconstruct a complete cardiac image.
2. Motion correction algorithms — This software can help compensate for cardiac motion to provide clearer images. This can help reduce the need for retakes and help reduce patient dose.
3. Cardiac metal artifact reduction software — Many cardiac patients have implanted hardware from previous procedures, including stents, surgical staples, sternum wires, septal or left atrial appendage (LAA) occluders, and pacemaker or implantable cardioverter defibrillator (ICD) leads. Any of these metal implants can cause metal artifact blooming or streaking artifacts that compromise the diagnostic quality of the images. The latest generation software offered by most vendors can largely compensate the photon starvation behind the metal or can reduce and cut through glare to see the underlying anatomy. Some newer software can increase image quality enough to visualize plaques or clots inside stents.
4. Calcium scoring software — Data continues to mount that calcium scoring is a good predictor of a patient’s risk for future coronary events. It is also being advocated for screenings of patients who are on the fence about going on statin therapy.
5. Plaque assessment software — This software is offered by all of the top CT system vendors and most of the third-party advanced visualization vendors. As more research accumulates and image resolution on CT scanners improves, quantifying the types of plaques seen in the coronary arteries on CT will likely play a bigger role. These CT assessments can help determine if an intervention is needed and help guide those interventions.
6. CT perfusion — This software tracks the iodine contrast concentration levels in the myocardium. The software reconstructs color coded maps showing areas of low concentration (areas of poor blood flow caused by ischemia), similar to nuclear myocardial perfusion exams that show areas of poor metabolic activity due to ischemia. The data from these exams is available almost immediately, whereas nuclear scans may require the patient to be admitted overnight.
7. TAVR / structural heart planning software — CT systems with workflows optimized for transcatheter aortic valve replacement (TAVR) or other structural heart exams will be helpful as these procedures continue to see rapidly increasing volumes. Software for TAVR, mitral valve assessments, LAA and septal defect occlusion planning should be considered in health systems offering these procedures.
8. FFR-CT assessment capability — As fractional flow reserve computed tomography (FFR-CT) gains reimbursement it is expected to see wider adoption. It can help definitively assess chest pain patients and either rule out coronary artery ischemia, or pinpoint the culprit lesions and the severity of blood flow obstruction, which can help better guide interventions. Invasive catheter-based FFR uses blood flow pressure readings before and after a coronary lesion to determine if a stenosis is hemodynamically significant and requires stenting. FFR-CT is noninvasive and uses super-computing, computational fluid dynamics to assess a virtual FFR, which may help eliminate the need for diagnostic catheterization.
For more insights on what to look for in cardiac CT scanners, watch the VIDEO “What to Consider When Comparing 64-slice to Higher Slice CT Systems,” an interview with Claudio Smuclovisky, M.D..