Optimised diffusion-weighting for measurement of apparent diffusion coefficient (ADC) in human brain
Optimised diffusion-weighting for measurement of apparent diffusion coefficient (ADC) in human brain
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DOI：
10.1016/s0730-725x(97)00037-4
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发表时间：
1997-01-01
影响因子：
2.5
通讯作者：
Hall, LD
中科院分区：
文献类型：
--
作者：
Xing, D;Papadakis, NG;Hall, LD
这项工作研究了扩散加权对表观扩散系数（ADC，或D）测量精度的影响，ADC值的精度用扩散噪声比(I)NR来描述，它是作为所得ADC的信噪比计算的。理论分析将DNR分解为扩散加权图像的信噪比和扩散加权的灵敏度“K-D”，后者反映了扩散加权域的采样策略对DNR的影响，理论分析表明，在xi = D(b(2)-b(1)) 1.1附近可以实现最优的两点扩散加权，其中xi为扩散加权的无量纲参数；b(1)和b(2)是两点扩散加权的扩散加权因子，该方法还导出了优化的信号平均方案，还考虑了两点方案用于体内ADC测量的局限性和限制；这一理论通过在幻影和健康志愿者的大脑上使用弥散加权回波平面成像方案的实验得到了验证，这导致了一个最佳的两点弥散加权，用于测量人脑中的ADC，使用b(1) = 300和b(2) 1550 +/- 100 s/mm(2)，这种两点方案成功地测量了人脑灰质、白质和脑脊液中的ADC值。因此，它为常用的多点方案提供了一种替代方案，并且具有需要显着缩短成像时间的优势，(C) 1997 Elsevier Science Inc.。
This work studies the effect of diffusion-weighting on the precision of measurements of the apparent diffusion coefficient (ADC, or D) by diffusion-weighted magnetic resonance imaging, The precision in the value of the ADC was described in terms of a diffusion-to-noise ratio (I)NR) which was calculated as the signal-to-noise ratio in the resultant ADC, A theoretical analysis decomposed the DNR into the signal-to-noise ratio in the diffusion-weighted image and the sensitivity of diffusion-weighting, ''K-D'', The latter reflects the effect of the sampling strategy in the diffusion-weighting domain on the DNR, The theoretical analysis demonstrated that optimal two-point diffusion-weighting could be achieved in the vicinity of xi = D(b(2)-b(1)) 1.1, where xi is a nondimensional parameter of diffusion-weighting, and b(1) and b(2) are the diffusion-weighting factors for the two-point diffusion-weighting, This approach also derived an optimised signal averaging scheme, The limitations and restrictions of the two-point scheme for in vivo ADC measurement were also considered; these included a detailed discussion on partial volume effects, The theory was verified by experiments on phantoms and on the brain of a healthy volunteer using a diffusion-weighted echo-planar imaging protocol, This led to an optimal two-point diffusion-weighting for ADC measurement in human brain using b(1) = 300, and b(2) 1550 +/- 100 s/mm(2), Such a two-point scheme successfully measured values of the ADC in gray matter, white matter and cerebrospinal fluid in human brain, It thus offers an alternative to the commonly used multiple-point schemes and has the advantage of requiring significantly shorter imaging times, (C) 1997 Elsevier Science Inc.