Technology insight: Cardiac CT angiography

Noninvasive coronary angiography has been the holy grail of cardiovascular medicine for decades. Cardiac CT angiography obtained with multislice CT technology is finally reaching the high standard in spatial resolution that is achieved by invasive X-ray coronary angiography. The latest 64-slice CT technology is a fast and safe modality for imaging the heart and coronary arteries, with scans taking seconds to complete. The temporal resolution of cardiac CT is still inferior, however, to that of invasive angiography, echocardiography or cardiac MRI. As such, this technique is still highly susceptible to motion artifacts created by the beating heart, and blooming artifacts due to the presence of calcium in the atherosclerotic plaque and to metallic implants. The routine use of agents to lower the heart rate before scanning is still required in most patients, and the timing of the contrast injection is critical for obtaining high-quality diagnostic cardiac images. Furthermore, cardiac CT angiography exposes the patient to substantial amounts of ionizing radiation and nephrotoxic contrast agents and, therefore, patients must be carefully selected based on a thorough understanding of the current clinical indications. In this review, I discuss the current multidetector row CT technology, safety issues, imaging protocols, clinical applications, and some of the challenges that still lie ahead with this modality.