Four-dimensional cardiac CT is a concept in evolution [1, 2]. In this paper, we define 4D cardiac CT as a processed study that assimilates a series of sequential, static, phase-specific, 3D volume helical data sets into a cine image that reflects the in vivo model of the 3D spatial information mapped to the sequential time and motion relationship of the cardiac cycle. It can be applied to derive morphologic and functional information, but it is distinct from existing tools, which deduce such information from static planar slices of end systole and end diastole alone. This technique will form an important facet of the comprehensive cardiac CT study.
The initial relatively high-speed acquisition of electron beam CT (EBCT) [3] provided some of the earliest quantitative CT information on ventricular size and shape and on systolic function. However, this complex technology was never widely available, was limited to prospective gating, and is fast being replaced by the the more versatile mechanical CT where its acquisition parameters in terms of temporal resolution are rapidly approaching those of EBCT. Earlier work with single-detector helical scanning was able to produce animated 2D images of the heart with ventricular values that closely correlated with conventional ventriculography [4].