Detection and Quantification of Coronary Calcium With Dual-Slice CT

Abstract

The introduction of dual-slice spiral technique by Elscint in 1992 allowed the imaging of the heart with 3-mm slices within 30 s (a breath-hold). The advantage of double-helical computed tomography (DHCT) over single-slice helical CT is its ability to acquire data twice as fast as single-slice helical CT owing to its two parallel arcs of detectors that are simultaneously irradiated by a single node. Both single- and dual-slice techniques acquire a volume of spatial information over several seconds without electrocardiographic gating. These data can be reconstructed into thin overlapping axial images, with an acquisition time for each image of approx 0.6–1.0 s. The use of overlapping methods compensates for the absence of electrocardiogram (ECG) triggering, enabling the detection of minimal spotty calcific lesions with an area threshold of 0.5 mm². This technique was further improved by the 4- and 16-slice multidetector spiral techniques, which enable the use of ECG triggering with subsecond slice time. The dual-slice technique of the Twin system (Philips LTD) is a contribution to practical cardiology. The noninvasive detection and measurement of the early stages of atherosclerosis within the wall of the coronary arteries provides the clinician with a new perspective on coronary artery disease (CAD) and adds important information to the current noninvasive methods. This chapter will summarize our experience of using the coronary calcium score in clinical practice.