The effect of spiral trajectory correction on pseudo-continuous arterial spin labeling with high-performance gradients on a compact 3T scanner

초록

Purpose: To demonstrate the feasibility of pseudo-continuous arterial-spin-labeled (pCASL) imaging with 3D fast-spin-echo stack-of-spirals on a compact 3T scanner (C3T), to perform trajectory correction for eddy-current-induced deviations in the spiral readout of pCASL imaging, and to assess the correction effect on perfusion-related images with high-performance gradients (80 mT/m, 700T/m/s) of the C3T. Methods: To track eddy-current-induced artifacts with Archimedean spiral readout, the spiral readout in pCASL imaging was performed with 5 different peak gradient slew rate (S-max) values ranging from 70 to 500 T/m/s. The trajectory for each S-max was measured using a dynamic field camera and applied in a density-compensated gridding image reconstruction in addition to the nominal trajectory. The effect of the trajectory correction was assessed with perfusion-weighted (Delta M) images and proton-density-weighted images as well as cerebral blood flow (CBF) maps, obtained from 10 healthy volunteers. Results: Blurring artifact on Delta M images was mitigated by the trajectory correction. CBF values on the left and right calcarine cortices showed no significant difference after correction. Also, the signal-to-noise ratio of Delta M images improved, on average, by 7.6% after correction (P < .001). The greatest improvement of 12.1% on Delta M images was achieved with a spiral readout using S-max of 300400 T/m/s. Conclusion: Eddy currents can cause spiral trajectory deviation, which leads to deformation of the CBF map even in cases of low value S-max. The trajectory correction for spiral-readout-based pCASL produces more reliable results for perfusion imaging. These results suggest that pCASL is feasible on C3T with high-performance gradients.

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