Cardiac computed tomography

Abstract

The use of computed tomography (CT) for imaging of the heart has evolved rapidly over the last three decades. The first CT scanner was developed in 1971 by Sir Godfrey Hounsfield. During the 1970s and 1980s, rapid advancements in technology enabled the use of CT scanners for the real-time assessment of stationary organs in the human body. Despite the development of slip-ring technology, allowing rotational gantry movement, it was considered that CT technology would never be capable of imaging the beating heart.The temporal limitations of mechanical gantry rotation were overcome by the development of electron- beam CT (EBCT) in the 1980s. With its high temporal resolution EBCT ushered in the new era of cross- sectional imaging for cardiac anatomy and cardiac function. The recognition of atherosclerotic calcification in the coronary artery as a surrogate marker for coronary disease, led to the development of calcium scoring and the extensive use of EBCT for coronary artery disease (CAD) assessment in the early 1990s. The late 1990s saw the introduction of the first contrast enhanced EBCT scans for the assessment of coronary disease; however, limitations of EBCT technology prevented its widespread dissemination.Simultaneously, the increasing availability of spiral and subsequently multi-detector row CT scanners spurred further research into the use of conventional CT systems for cardiac imaging. The scans were initially performed on spiral and 4-slice scanners which had poor spatial resolution and a temporal resolution lower than EBCT. The subsequent development of 16, 32, and 64-slice CT scanners significantly reduced image acquisition times, vastly improved spatial and temporal resolution, and provided clinically useful images of the coronary arteries. Improvements in image reconstruction time (greater computational power), faster gantry rotation speeds (∼350 msec), improved spatial resolution of the CT detectors (0.4–0.6 mm), and the utilization of beta-blocker medications to induce transient bradycardia, further enhanced the quality of cardiac CT examinations. This led to the rapid realization of cardiac CT and in particular CT coronary angiography (CTCA) as a viable non- invasive tool in the diagnostic armamentarium for cardiovascular disease.Most of the landmark papers discussed in this chapter have been selected because they highlight the important advances in the technique and justification for CTCA, which forms the bulk of cardiac CT examinations. Many of the concepts described in these publications are applicable to other cardiac CT indications and have served in firmly establishing CTCA as a valuable technique in the diagnostic pathway for cardiac disease.