Optimal acquisition schemes for in vivo quantitative magnetization transfer MRI
Optimal acquisition schemes for in vivo quantitative magnetization transfer MRI
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DOI：
10.1002/mrm.21003
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发表时间：
2006-10-01
影响因子：
3.3
通讯作者：
Alexander, Daniel C.
中科院分区：
文献类型：
--
作者：
Cercignani, Mara;Alexander, Daniel C.
本文使用 Cramer-Rao 下界 [CRLB] 理论来获得体内定量磁化转移 (MT) 成像的最佳采集方案，尽管该方法通常适用于任何多参数 MRI 技术。定量 MT 将两池模型拟合到在 MT 饱和脉冲中的不同采样点或幅度和偏移频率设置处收集的数据。在这里，我们使用基于 CRLB 的简单目标函数来同时优化多个参数的采样策略，并使用模拟退火来最小化这些关于采样配置的目标函数。实验将 1.5T 人类白质 (WM) 定量 MT 的最佳方案与之前发布的使用合成数据和人脑数据的方案进行比较。结果表明，新方案的拟合参数误差大大降低，大大增加了体内定量 MT 的临床潜力。由于采样方案优化需要对 MT 参数进行特定设置，因此我们还表明，在大脑中观察到的 MT 参数范围内，最佳方案对于这些设置是稳健的。
This paper uses the theory of Cramer-Rao lower bounds [CRLB) to obtain optimal acquisition schemes for in vivo quantitative magnetization transfer (MT) imaging, although the method is generally applicable to any multiparametric MRI technique. Quantitative MT fits a two-pool model to data collected at different sampling points or settings of amplitude and offset frequency in the MT saturation pulses. Here we use simple objective functions based on the CRLB to optimize sampling strategies for multiple parameters simultaneously, and use simulated annealing to minimize these objective functions with respect to the sampling configuration. Experiments compare optimal schemes derived for quantitative MT in the human white matter (WM) at 1.5T with previously published schemes using both synthetic and human-brain data. Results show large reductions in error of the fitted parameters with the new schemes, which greatly increases the clinical potential of in vivo quantitative MT. Since the sampling-scheme optimization requires specific settings of the MT parameters, we also show that the optimum schemes are robust to these settings within the range of MT parameters observed in the brain.