Itskovich Vitalii V, Mani Venkatesh, Mizsei Gabor, Aguinaldo Juan Gilberto S, Samber Daniel D, Macaluso Frank, Wisdom Paul, Fayad Zahi A
Imaging Science Laboratories, Mount Sinai School of Medicine, New York, New York 10029-6574, USA.
J Magn Reson Imaging. 2004 Apr;19(4):459-67. doi: 10.1002/jmri.20022.
To reduce long examination times of black-blood vessel wall imaging by acquiring multiple slices simultaneously and by using parallel acquisition techniques.
DIR-rapid acquisition with relaxation enhancement (RARE) techniques imaging up to 10 simultaneous slices per acquisition with single and multiple 180 degrees -reinversion pulses were developed. A slab-selective reinversion multislice DIR-RARE sequence incorporating generalized autocalibrating partially parallel acquisitions (GRAPPA) imaging was implemented. Four-channel and eight-channel carotid coils were built to test these sequences. A total of 11 subjects were studied. Contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR) efficiency factor (SEF, SNR/unit time/slice) were measured from aortic images of three healthy subjects to determine optimal MR parameters. The DIR-RARE-GRAPPA sequence was run on aortas and carotid arteries of the five remaining healthy subjects and three atherosclerotic patients with optimal parameters (acquisition times 12-21 seconds).
SEFs of slab-selective protocols were significantly higher than those of slice-selective protocols, and SEFs of DIR-RARE-GRAPPA protocols were significantly higher than corresponding non-GRAPPA protocols (P < 0.05). CNR was not significantly different for all imaging protocols. The DIR-RARE-GRAPPA multislice sequence showed 8.35-fold time improvement vs. single-slice DIR-2RARE sequence.
Future MRI atherosclerotic plaque studies can be performed in substantially shorter times using these methods.
通过同时采集多个层面并使用并行采集技术来减少黑血血管壁成像的长时间检查。
开发了具有弛豫增强（RARE）技术的DIR快速采集方法，每次采集可同时成像多达10个层面，采用单180度和多个180度重反转脉冲。实施了结合广义自校准部分并行采集（GRAPPA）成像的层面选择重反转多层DIR-RARE序列。构建了四通道和八通道颈动脉线圈来测试这些序列。共研究了11名受试者。从三名健康受试者的主动脉图像测量对比噪声比（CNR）和信噪比（SNR）效率因子（SEF，SNR/单位时间/层面）以确定最佳MR参数。以最佳参数（采集时间12 - 21秒）在其余五名健康受试者的主动脉和颈动脉以及三名动脉粥样硬化患者上运行DIR-RARE-GRAPPA序列。
层面选择方案的SEF显著高于层面选择方案，DIR-RARE-GRAPPA方案的SEF显著高于相应的非GRAPPA方案（P < 0.05）。所有成像方案的CNR无显著差异。DIR-RARE-GRAPPA多层序列与单层DIR-2RARE序列相比，时间改善了8.35倍。
使用这些方法，未来的MRI动脉粥样硬化斑块研究可以在显著更短的时间内进行。
