Barker P B, Hearshen D O, Boska M D
Department of Neurology, Henry Ford Hospital, Detroit, Michigan, USA.
Magn Reson Med. 2001 May;45(5):765-9. doi: 10.1002/mrm.1104.
Single-voxel proton spectra of the human brain were recorded in five subjects at both 1.5T and 3.0T using the STEAM pulse sequence. Data acquisition parameters were closely matched between the two field strengths. Spectra were recorded in the white matter of the centrum semiovale and in phantoms. Spectra were compared in terms of resolution and signal-to-noise ratio (SNR), and transverse relaxation times (T(2)) were estimated at both field strengths. Spectra at 3T demonstrated a 20% improvement in sensitivity compared to 1.5T at short echo times (TE = 20 msec), which was lower than the theoretical 100% improvement. Spectra at long echo times (TE = 272 msec) exhibited similar SNR at both field strengths. T(2) relaxation times were almost twofold shorter at the higher field strength. Spectra in phantoms demonstrated significantly improved resolution at 3T compared to 1.5T, but resolution improvements in in vivo spectra were almost completely offset by increased linewidths at higher field.
使用STEAM脉冲序列，在5名受试者中于1.5T和3.0T场强下记录了人脑的单体素质子谱。两个场强之间的数据采集参数紧密匹配。在半卵圆中心的白质和模型中记录光谱。比较了光谱的分辨率和信噪比（SNR），并在两个场强下估计横向弛豫时间（T(2)）。在短回波时间（TE = 20毫秒）时，3T光谱的灵敏度比1.5T提高了20%，低于理论上100%的提高。在长回波时间（TE = 272毫秒）时，两个场强下的光谱表现出相似的SNR。在较高场强下，T(2)弛豫时间几乎缩短了两倍。与1.5T相比，模型中的光谱在3T时分辨率显著提高，但体内光谱分辨率的提高几乎完全被较高场强下增加的线宽所抵消。
