Scientific Department, Fondazione IRCCS Istituto Neurologico Carlo Besta, via Celoria 11, Milan, Italy.
MAGMA. 2010 Apr;23(2):115-21. doi: 10.1007/s10334-010-0208-9. Epub 2010 Apr 8.
To investigate whether spacing (Delta) and duration (delta) of the diffusion-sensitizing gradient pulses differentially affect exponential (D'), biexponential (D (slow), D (fast) and f (slow)) and diffusional kurtosis (D and K) model parameters.
Measurements were performed in the rat thalamus for b = 200-3,200 s mm(-2), sweeping Delta between 20 and 100 ms at delta = 15 ms, and delta between 15 and 50 ms at Delta = 60 ms. Linear regressions were performed for each model parameter vs. Delta or delta.
Increasing Delta from 20 to 100 ms increases D' (from 0.64 to 0.70 x 10(-3) mm(2)s(-1)) and D (slow) (from 0.26 to 0.33 x 10(-3) mm(2)s(-1)), reduces K (from 0.57 to 0.53), and has no effects on D (fast), f (slow) or D. Increasing delta from 15 to 50 ms increases D (from 0.80 to 0.88 x 10(-3) mm(2)s(-1)), and has no effects on the other parameters.
The parameters of the biexponential and diffusional kurtosis models are more sensitive than the exponential model to Delta and delta; however, observed effects are too small to account for the discrepancies found in literature.
研究扩散敏感梯度脉冲的间隔（Delta）和时长（delta）是否会对指数（D'）、双指数（D(slow)、D(fast)和 f(slow)）和扩散峰度（D 和 K）模型参数产生不同影响。
在大鼠丘脑内进行 b = 200-3200 s/mm(-2)的测量，在 delta = 15 ms 时，Delta 在 20-100 ms 之间变化，在 Delta = 60 ms 时，delta 在 15-50 ms 之间变化。针对每个模型参数与 Delta 或 delta 进行线性回归。
Delta 从 20 增加到 100 ms，会使 D'（从 0.64 增加到 0.70 x 10(-3)mm(2)s(-1)）和 D(slow)（从 0.26 增加到 0.33 x 10(-3)mm(2)s(-1)）增加，K（从 0.57 减少到 0.53）减少，对 D(fast)、f(slow)或 D 没有影响。delta 从 15 增加到 50 ms，会使 D（从 0.80 增加到 0.88 x 10(-3)mm(2)s(-1)）增加，对其他参数没有影响。
双指数和扩散峰度模型的参数比指数模型对 Delta 和 delta 更敏感；然而，观察到的影响太小，无法解释文献中发现的差异。
