Multidetector CT: The Heart of Cardiac Imaging

Twitter icon
Facebook icon
LinkedIn icon
e-mail icon
Google icon

Philips Brilliance CTSixty-four slice CT is hot. Most facilities fall into one of three categories: implementers of CT’s latest workhorse, those on the brink of installing it or those actively analyzing and budgeting for the technology. In all, about 40 percent of healthcare sites across the country have added 64-slice CT to their imaging arsenal — amazing since it’s only been on the market for two years.

The primary driver for 64-slice CT is cardiac imaging; the technology truly enables non-invasive coronary artery imaging. But deploying 64-slice CT is a multi-faceted process. To fully optimize the technology, healthcare facilities need to understand its clinical utility and address issues such as post-processing, storage and business planning.

The clinical rationale

Coronary artery imaging with multidetector CT is not synonymous with 64-slice technology. Five years ago, University of Maryland Medical Center in Baltimore based its coronary imaging program on a four-slice CT system. The program graduated to 16- and 40-slice scanners and now relies on a pair of Philips Medical Systems Brilliance 64-slice CT scanners. The difference with 64-slice CT boils down to resolution and clinical capabilities.

Sixty-four slice technology offers better spatial and temporal resolution than its predecessors, yielding better coronary artery images for more patients. “This system allows us to non-invasively image the coronary arteries on a routine basis,” explains Charles White, MD, vice chairman of radiology. Improved spatial resolution is essential for contrary imaging, says Tony DeFrance, MD, medical director CVCTA Education Center in San Francisco, Calif., who uses Toshiba America Medical Systems Aquilion 64 scanner.

Sixty-four slice CT scanners generate thousands of submillimeter slices. More and thinner slices translate into better images of large coronary arteries, which measure about 4 millimeters. In addition, scan time drops to a reasonable 6 to 8 seconds, which is a feasible breath hold for most patients. The brief scan time reduces the chance of an arrhythmia or the patient releasing his breath and produces clearer images. In addition, improved temporal resolution limits blurred images and artifacts. The upshot? “Sixty-four slice CT will change the way cardiac disease is diagnosed and managed,” claims DeFrance.

The ability to visualize the coronary arteries and view and characterize plaque have taken the cardiac imaging world by storm; however, the technology is outpacing clinical trials, says DeFrance. “The field is changing rapidly,” adds James Min, MD, director of cardiac CT lab at Cornell University and a GE Healthcare Lightspeed VCT user. The current model at many sites is to use 64-slice CT as the diagnostic test of choice for low to intermediate risk chest pain patients. The scanners offer a means of rapidly deciding how to best treat these patients.

But several factors may limit adoption of 64-slice technology. DeFrance says some physicians are reluctant to adopt 64 because the return on investment can be relatively lengthy compared to other systems like cardiac nuclear cameras. What’s more, installation and education can be time-consuming, and there are disparities in reimbursement.

These barriers, however, are fairly manageable and can be overcome with comprehensive clinical and business planning. “The practice model that works best is the cooperative relationship between cardiologists and radiologists. These specialists need to understand that their strengths and weaknesses complement each other,” notes DeFrance. That is, the expertise of the radiologist is required for non-cardiac images, and the cardiac know-how addresses the cardiac portion of the scan. The benefits of the cooperative model transcend the clinical as it can be difficult to break even on cardiac scanning alone. Peripheral vascular work and non-vascular scans can round out the program to boost the bottom line.

In addition, sites need to develop a post-processing plan. Take for example University of Maryland Medical Center. For most cases, 3D technologists handle the lion’s share of post-processing for images produced on the Brilliance scanner, which includes reviewing wall motion and completing stenosis assessments and ejection fraction calculations. Then the radiologist reviews the images and fine-tunes the images as necessary. This model requires well-trained technologists, says White. The Cornell cardiac CT lab uses techs for retrospective reconstruction of different