What are the basic concepts of temporal, contrast, and spatial resolution in cardiac CT?

Abstract

An imaging instrument can be characterized by its spatial resolution, contrast resolution, and temporal resolution. The capabilities of computed tomography (CT) relative to other cardiac imaging modalities can be understood in these terms. The purpose of this review is to characterize the spatial, contrast, and temporal resolutions of cardiac CT in practical terms.

Figure 1

Linear attenuation coefficient versus x-ray energy. For CT imaging, the body is imaged with x-rays in the range of 20–140 keV. In this range, soft tissues have little variation in their attenuation coefficients, leading to low soft tissue contrast and the need for contrast agents such as iodine.

Figure 2

Single-segment versus multisegment reconstruction. In single-segment reconstruction, an image is reconstructed from data from a prescribed time range in a single R-R interval. In multisegment reconstruction, the same image would be reconstructed from data from the same phase of multiple cardiac cycles, with a smaller time range (higher temporal resolution) in each R-R interval than with single-segment reconstruction. In the specific case shown in this figure, the temporal resolution would be increased by a factor of 3 with multisegment reconstruction.