Diffusion tensor imaging and fiber tractography of the median nerve at 1.5T: optimization of b value
Diffusion tensor imaging and fiber tractography of the median nerve at 1.5T: optimization of b value
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DOI：
10.1007/s00256-008-0577-6
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发表时间：
2009-01-01
影响因子：
2.1
通讯作者：
Sussman, Marshall S.
中科院分区：
文献类型：
--
作者：
Andreisek, Gustav;White, Lawrence M.;Sussman, Marshall S.
本研究的目的是系统地评估1.5 t时正中神经弥散张量成像和纤维束造影的最佳b值。这是一项前瞻性研究，经机构审查委员会批准并获得研究对象的书面知情同意。15名健康志愿者（7男8女，平均年龄31.2岁）接受了手腕弥散张量成像。在325 ~ 1550 s/mm2的8个不同的b值下，对每个受试者进行单次旋转回波回波平面成像序列（TR/TE, 7000/103 ms）。计算正中神经重建纤维束数和长度、纤维密度指数（FDi）、各向异性分数（FA）和表观扩散系数（ADC）。同时计算每次采集的信噪比（SNR）。整体图像质量由两位读者一致评估，通过对每个受试者的代表性纤维束图像进行评分，评分范围从1到8（1 =最佳到8 =最差图像质量）。最长纤维的b值在675 ~ 1025 s/mm2之间。最大FDi值为1025 s/mm2。所有b值的FA均在0.5 ~ 0.6之间。随着b值的增加，ADC从1.44 × 10-3逐渐降低到0.92 × 10-3 mm2/s。最大信噪比+/-标准差在b值最低时为175.4 +/- 72.6，随b值的增加而减小。b值为1025 s/mm2时的信噪比为最大信噪比的48.5%。b值为1025 s/mm2时，纤维束图像质量最佳。1.5 T时正中神经弥散张量成像和纤维束造影的最佳b值为1025 s/mm2。
The objective of this study was to systematically assess the optimal b value for diffusion tensor imaging and fiber tractography of the median nerve at 1.5 T.This is a prospective study which was carried out with institutional review board approval and written informed consent from the study subjects. Fifteen healthy volunteers (seven men, eight women; mean age, 31.2 years) underwent diffusion tensor imaging of the wrist. A single-shot spin-echo-based echo-planar imaging sequence (TR/TE, 7000/103 ms) was performed in each subject at eight different b values ranging from 325 to 1,550 s/mm2. Number and length of reconstructed fiber tracts, fiber density index (FDi), fractional anisotropy (FA), and apparent diffusion coefficient (ADC) were calculated for the median nerve. Signal-to-noise ratio (SNR) was also calculated for each acquisition. The overall image quality was assessed by two readers in consensus by ranking representative fiber tract images for each subject using a scale range from 1 to 8 (1 = best to 8 = worst image quality).Longest fibers were observed for b values between 675 and 1,025 s/mm2. Maximum FDi was found at b values of 1,025 s/mm2. FA was between 0.5 and 0.6 for all b values. ADC gradually decreased from 1.44 x 10-3 to 0.92 x 10-3 mm2/s with increasing b values. Maximum SNR +/- standard deviation (175.4 +/- 72.6) was observed at the lowest b value and decreased with increasing b values. SNR at b values of 1,025 s/mm2 was 48.5% of the maximum SNR. Optimal fiber tract image quality was found for b values of 1,025 s/mm2.The optimal b value for diffusion tensor imaging and fiber tractography of the median nerve at 1.5 T was 1,025 s/mm2.