Computed tomographic and magnetic resonance coronary angiography: are you ready?

Within the next year or two, magnetic resonance angiography (MRA) and computed tomographic angiography (CTA) most likely will be used to deliver clinically useful images of the coronary arteries. The spatial resolution of CTA combined with new 16-detector scanners and cardiac imaging software will render views of the coronary arteries that will rival or surpass the spatial resolution and far surpass the contrast resolution of conventional coronary angiography (CA). MRA will potentially offer coronary artery imaging without the need for iodinated contrast injection. CTA and MRA of the coronary arteries offer distinct advantages over CA. Both CTA and MRA may be able to characterize plaques of the coronary arteries. Currently, CA can only detect degree of stenosis, collateral patterns and presence of dense calcification of the coronary arteries. CTA and MRA offer the promise of improved plaque characterization. CTA and MRA of the coronary arteries promise, at the least, to detect plaque not seen by CA and to offer some degree of characterization. According to some non-published data, advances in CT in the next five years may offer characterization of plaque equal to or superior to IVUS. To prepare for this "certainty," radiology departments must answer many questions. Each department will have it's own unique equipment requirements, though the size of the department and imaging volumes will determine what type of scanner will be purchased for CTA/MRA of the coronary arteries. Each department will require physicians and technologists trained in advanced CT and MRI imaging techniques including cardiac gating, 3D and 4D multi-planar reconstructions, advanced coronary artery and cardiac anatomy, and personnel with advanced patient management skills to handle the unique needs of patients with coronary artery disease. To transition a department into full-service cardiac CT or MRI, small steps can be taken over the next few years to allow referring physicians and department personnel to acquaint themselves to the needs of patients seeking coronary imaging. Current multi-detector CT scanners with two, four or eight detector rows perform prospectively gated coronary CT calcification scoring. While still controversial, coronary calcium scoring offers a reasonable non-invasive method for determining risk of significant coronary artery disease in asymptomatic patients. Once a department has experience with coronary calcium imaging of asymptomatic patients, the next step would be to consider coronary artery imaging. While four-detector or eight-detector CT scanners may be useful for this task, there is a growing consensus that 16 or more detector rows are required to perform consistent high quality CTA of the coronary arteries. The cost of these scanners is still undetermined. However, one can expect to pay at least double the cost of a conventional scanner for a 16-detector unit at this time. With additional software for cardiac imaging, the costs can be well over a million dollars for a CT scanner. If the volume of additional patients from coronary CTA meets the promise of this new technology, the cost difference should be affordable even to smaller hospitals. As radiology professionals we possess equipment knowledge and have the imaging and technical skills to perform high quality cardiac imaging with CT and MRI. We need to add to and refine our knowledge of anatomy and become "team players" for management of patients with coronary and cardiac disease. If not us, then who? Are you ready? Are you willing to get ready?