Multivoxel 3D proton spectroscopy in the brain at 1.5 versus 3.0 T: signal-to-noise ratio and resolution comparison.
Multivoxel 3D proton spectroscopy in the brain at 1.5 versus 3.0 T: signal-to-noise ratio and resolution comparison.
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发表时间：
2001-10
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通讯作者：
O. Gonen;Stephan Gruber;Belinda S.Y. Li;Vladimir Mlynarik;Ewald Moser
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作者：
O. Gonen;Stephan Gruber;Belinda S.Y. Li;Vladimir Mlynarik;Ewald Moser
新的3.0-T成像仪理论上产生的信噪比（SNR）和光谱分辨率是1.5-T仪器的两倍。为了评估多体素3D质子磁共振波谱（1H-MRS）在人脑中的可能改进，我们比较了两种场强的SNR和光谱分辨率性能。方法对4例21-29岁受试者在1.5T和3.0T下进行三维1H-MRS检查。在每种情况下，在16 x 16 x 3 cm的视野内获得9 x 9 x 3 cm的感兴趣体积，该视野被划分为4个（0.75 cm厚）16 x 16体素切片，每次检查产生324（0.75 cm 3）个信号体素。结果在大约27分钟的采集协议中，在相同受试者的相同脑区域中，3.0 T与1.5 T下的平均体素SNR增加23-46%。N-乙酰天冬氨酸、肌酸和胆碱的SNR分别如下：1.5 T时为15.3 +/- 4、8.2 +/- 2.2和8.0 +/- 2.0，3.0 T时为22.4 +/- 7.0、10.1 +/- 3.5和10.1 +/- 3.6。在约900个体素中，1.5 T时的光谱分辨率（代谢物线宽）为3.5 +/- 0.5 Hz，3.0 T时为6.1 +/- 1.5 Hz。在3.0 T下，光谱基线明显更平坦。结论在实际实验中，由于固有的和可控的因素，信噪比和光谱分辨率的预期增益并没有完全实现。然而，所获得的23-46%的改善使得能够进行更可靠的峰面积估计，并且在3.0 T时与1.5 T时相比，1H-MRS采集时间缩短约50%。
BACKGROUND AND PURPOSE The new 3.0-T imagers theoretically yield double the signal-to-noise ratio (SNR) and spectral resolution of 1.5-T instruments. To assess the possible improvements for multivoxel 3D proton MR spectroscopy (1H-MRS) in the human brain, we compared the SNR and spectral resolution performance with both field strengths. METHODS Three-dimensional 1H-MRS was performed in four 21-29-year-old subjects at 1.5 and 3.0 T. In each, a volume of interest of 9 x 9 x 3 cm was obtained within a field of view of 16 x 16 x 3 cm that was partitioned into four (0.75-cm-thick) 16 x 16-voxel sections, yielding 324 (0.75-cm3) signal voxels per examination. RESULTS In an acquisition protocol of approximately 27 min, average voxel SNRs increased 23-46% at 3.0 versus 1.5 T in the same brain regions of the same subjects. SNRs for N-acetylaspartate, creatine, and choline, respectively, were as follows: 15.3 +/- 4, 8.2 +/- 2.2, and 8.0 +/- 2.0 at 1.5 T and 22.4 +/- 7.0, 10.1 +/- 3.5, and 10.1 +/- 3.6 at 3.0 T. Spectral resolution (metabolite linewidths) were 3.5 +/- 0.5 Hz at 1.5 T versus 6.1 +/- 1.5 Hz at 3.0 T in approximately 900 voxels. Spectral baselines were noticeably flatter at 3.0 T. CONCLUSION Expected gains in SNR and spectral resolution were not fully realized in a realistic experiment because of intrinsic and controllable factors. However, the 23-46% improvements obtained enable more reliable peak-area estimation and an 1H-MRS acquisition approximately 50% shorter at 3.0 versus 1.5 T.