Christoph R. Becker

Multi-Slice Cumputed Tomography Technical Principles, Clinical Application and Future Perspective

Coronary artery imaging is a demanding application for any non-invasive imaging modality. On the one hand, high temporal resolution is needed to virtually freeze the cardiac motion and to avoid motion artifacts in the images. On the other hand, sufficient spatial resolution - at best sub-millimeter - is required to adequately visualize small and complex anatomical structures like the coronary arteries. The complete coronary artery tree has to be examined within one short breath-hold time to avoid breathing artifacts and to limit the amount of contrast agent if necessary. In 1984, electron beam CT (EBCT) was introduced as a non-invasive imaging modality for the diagnosis of coronary artery disease (Boyd and Liption 1982; Agatstonet al. 1990; Achenbach et al. 1998; Becker et al. 2000a). The temporal resolution of 100 ms allows for motion-free imaging of the cardiac anatomy in the diastolic heart phase even at higher heart rates. Due to the restriction to non-spiral scanning in ECG-synchronized cardiac investigations, a single breath-hold scan of the heart requires slice widths not smaller than 1.5-3 mm.

Technical Principles of CT

The first computed tomography (CT) systems, introduced in 1972, produced image slices which represent the distribution of the object’s X-ray attenuation in the image plane. Since then the progress to third generation fan beam geometry and continuous spiral scanning has changed CT from a sequential single-slice imaging technology to a continuous-volume imaging modality. The introduction of spiral acquisition in 1991 was a first breakthrough for CT in vascular diagnosis with contrast-enhanced CT angiography (CTA) examinations. A second major leap in CT technology came with the advent of multislice acquisition in 1998. This technology allows for almost isotropic three-dimensional (3D) spatial resolution, short examination times, and coverage of large volumes for CT angiographic imaging of the abdominal, cerebral, and peripheral vessels. Furthermore, very short image acquisition times due to increased gantry rotation speed in combination with ECG synchronization allow for diagnosis of the heart, the cardiovascular vessels, and the coronary arteries.