High Spatial Frequencies Are More Dynamic Than Low Spatial Frequencies In Cardiac Motion

Introduction Effective strategies for sparse sampling of kt-space are important for fast dynamic imaging. Following observations in early landmark papers [1-3] the temporal sampling rate of each k-space view is often linked to the signal energy represented by that view in k-space for a certain class of images, in general considering only the spatial or spatiotemporal spectrum of the entire image. Based on resulting criteria, sparse sampling schemes typically sample low spatial frequencies more frequently than high spatial frequencies, implicitly considering signal-to-noise ratio SNR as the dominant factor in image quality [1-4]. For cardiac imaging this concept is represented by the BRISK formalism [2]. Sampling schemes for angiography and dynamic lesion enhancement imaging were established by TRICKS [3] and STBB [4]. In this work we have studied analysis of temporal spectral content as a function of the k-space frequency, illustrated with simulated and actual ciné cardiac imaging data. Dynamic spectral content was observed both globally in the image, and spatially-selectively in relevant portions of the image.