Sensitivity-encoded (SENSE) proton echo-planar spectroscopic imaging (PEPSI) in the human brain
Sensitivity-encoded (SENSE) proton echo-planar spectroscopic imaging (PEPSI) in the human brain
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DOI：
10.1002/mrm.21119
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发表时间：
2007-02-01
影响因子：
3.3
通讯作者：
Posse, Stefan
中科院分区：
文献类型：
--
作者：
Lin, Fa-Hsuan;Tsai, Shang-Yueh;Posse, Stefan
磁共振波谱成像 (MRSI) 提供了空间分辨的代谢物信息，这对于神经科学研究和临床应用都是非常宝贵的。然而，耗时的相位编码导致数据采集时间过长，这对 MRSI 来说是一个重大挑战。使用平面回波读出梯度的快速 MRSI 脉冲序列（例如质子回波平面光谱成像 (PEPSI)）能够进行快速光谱 I-空间 I 编码，从而加快图像采集时间。将 PEPSI 与利用射频线圈阵列的并行 MRI 的最新进展相结合，可以进一步加速 MRSI 数据采集。在这里，我们通过使用八通道头部线圈阵列将 PEPSI 与灵敏度编码 (SENSE) MRI 相结合，研究高场（3T 和 4T）超快光谱成像的可行性。我们表明，根据场强，在短 TE（15 ms）下获取单平均 SENSE-PEPSI 数据可以加速至 32 s 或更短，以获得具有可接受的光谱质量和定位的胆碱 (Cho)、肌酸 (Cre)、N-乙酰基天冬氨酸 (NAA) 和 J 耦合代谢物（例如谷氨酸 (Glu) 和肌醇 (Ino)）的代谢图像。实验测量的代谢物共振信噪比 (SNR) 和 Cramer-Rao 下限 (CRLB) 的降低可以通过 g 因子和减少的测量时间得到很好的解释。因此，该技术是减少 3D 采集和时间分辨 2D 测量扫描时间的一种有前景的方法。
Magnetic resonance spectroscopic imaging (MRSI) provides spatially resolved metabolite information that is invaluable for both neuroscience studies and clinical applications. However, lengthy data acquisition times, which are a result of time-consuming phase encoding, represent a major challenge for MRSI. Fast MRSI pulse sequences that use echo-planar readout gradients, such as proton echo-planar spectroscopic imaging (PEPSI), are capable of fast spectra I-spatia I encoding and thus enable acceleration of image acquisition times. Combining PEPSI with recent advances in parallel MRI utilizing RF coil arrays can further accelerate MRSI data acquisition. Here we investigate the feasibility of ultrafast spectroscopic imaging at high field (3T and 4T) by combining PEPSI with sensitivity-encoded (SENSE) MRI using eight-channel head coil arrays. We show that the acquisition of single-average SENSE-PEPSI data at a short TE (15 ms) can be accelerated to 32 s or less, depending on the field strength, to obtain metabolic images of choline (Cho), creatine (Cre), N-acetyl-aspartate (NAA), and J-coupled metabolites (e.g., glutamate (Glu) and inositol (Ino)) with acceptable spectral quality and localization. The experimentally measured reductions in signal-to-noise ratio (SNR) and Cramer-Rao lower bounds (CRLBs) of metabolite resonances were well explained by both the g-factor and reduced measurement times. Thus, this technology is a promising means of reducing the scan times of 3D acquisitions and time-resolved 2D measurements.