| 总结: | Purpose: The goal of this study was to achieve high temporal resolution, multi-time point pseudo-continuous arterial spin labeling (pCASL) MRI in a time efficient manner, while maintaining whole brain coverage. Methods: A Hadamard 8-matrix was used to dynamically encode the pCASL labeling train, thereby providing the first source of temporal information. The second method for obtaining dynamic ASL signal consisted of a Look-Locker (LL) readout of four phases that are acquired with a flip-angle sweep to maintain constant sensitivity over the phases. To obtain whole brain coverage in the short LL interval, four slices were excited simultaneously by multi-banded RF pulses. After subtraction according to the Hadamard scheme, the ASL signal was corrected for the use of the flip-angle sweep and background suppression pulses. The BASIL toolkit of the Oxford Centre for FMRIB was used to quantify the ASL signal. Results: By combining a time-encoded pCASL labeling scheme with a LL readout and simultaneous multi-slice acquisition, 28 time points of 16 slices with a 75 or 150 ms time-resolution were acquired in a total scan time of 10m20s. From which cerebral blood flow (CBF) maps, arterial transit time (ATT) maps and the arterial blood volume could be determined. Conclusion: Whole brain ASL images were acquired with a 75 ms time-resolution for the angiography and 150 ms resolution for the perfusion phase by combining the proposed techniques. Reducing the total scan time to 1m18s still resulted in reasonable CBF maps, which demonstrates the feasibility of this approach for practical studies on brain hemodynamics.
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