Spatial, Temporal Resolution and Signal-to-Noise Ratio

Abstract

Spatial resolution and temporal resolution refer to the smallest distance and temporal change that can be differentiated. Signal-to-noise ratio (SNR) is a reflection of signal intensity with reference to the background noise. In cardiac MR imaging, it is desirable to acquire images that have adequate spatial resolution to resolve fine structures in the heart, sufficient temporal resolution to visualize cardiac motion, and high SNR for good image quality. This chapter first covers spatial resolution in MRI, its relationship to k-space, the difference between nominal and apparent spatial resolution, and factors that affect spatial resolution. The chapter then discusses temporal resolution and image acquisition methods that can be used to change/improve temporal resolution, including view-sharing, segmented imaging, and real-time imaging. Finally, the chapter covers SNR and sources of noise, factors affecting SNR, how to measure SNR, and the tradeoffs between SNR, spatial resolution and temporal resolution.