Figure 1:

A, A schematic of a fivefold-accelerated dual-imaging cardiac perfusion pulse sequence for sampling one arterial input function (AIF) plane and at least three short-axis (SAX) planes per heartbeat. In the first two repetitions with a 4-second delay between the first two acquisitions, proton density (PD)–weighted images are acquired by not playing the wideband saturation pulse. For the AIF scan, images are acquired with a saturation recovery time to the center of k-space (TS) of 20 msec and centric k-space ordering. For the myocardial perfusion (MP) scan, images are obtained with a TS of 82 msec and linear k-space ordering. B, AIF and MP planes prescription with respect to a four-chamber plane. C, Fivefold-accelerated latticelike k-space sampling pattern sampling 38 k-space lines with higher density at the center of the k-space. Left: AIF acquisition with centric k-space ordering. Right: TS acquisition with linear k-space ordering. In region 1, the central k-space line is always sampled (R = 1). In region 2, the next 10 k-space lines (five above, five below) outward from the central line are sampled (R = 2). In region 3, the next 16 k-space lines (eight above, eight below) outward from region 2 are sampled (R = 4). In region 4, the next 20 k-space lines (10 above, 10 below) outward from region 3 are sampled (R = 5). In region 5, the remaining 143 k-space lines (72 above, 71 below) outward from region 4 are sampled (R = 6). This latticelike k-space sampling pattern achieves incoherence by varying density along ky, while ensuring that every k-space line is sampled at least once through time for improved self-calibration of coil sensitivities. ECG = electrocardiogram, Mz = longitudinal magnetization, T1W = T1-weighted.