Imaging parameter effects in apparent diffusion coefficient determination of magnetic resonance imaging
Imaging parameter effects in apparent diffusion coefficient determination of magnetic resonance imaging
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DOI：
10.1016/j.ejrad.2009.06.031
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发表时间：
2011-01-01
影响因子：
3.3
通讯作者：
Maeda, Fumie
中科院分区：
文献类型：
--
作者：
Ogura, Akio;Hayakawa, Katsumi;Maeda, Fumie
目的：虽然表观扩散系数(ADC)值常用于肿瘤的鉴别诊断，但它随扫描参数的不同而不同。方法：采用弥散加权成像技术，通过改变b值(b=0~3000 S/mm(2))、重复时间(Tr)和回声时间(TE)对模型的ADC值进行扫描，确定各参数对ADC值的影响。此外，还测量了不同b值(b=0~10,000 S/mm(2))的正常志愿者脑的ADC值。结果：所有模体的扩散衰减曲线均为双指数拟合法。双指数衰减的快慢分量相交的点称为转折点。在每个体模中，从双指数曲线交叉的转折点的b值不同。转折点的b值取决于快速扩散分量的ADC值。当使用转折点的前后两个b值计算ADC时，ADC值可能不同。因此，必须按照b值进行计算，直到转折点，以获得快分量的ADC值。此外，为避免血液灌流的影响，建议b>；=100。此外，选择长的TR和短的TE是准确测量ADC的有效方法。结论：确定测量ADC的转折点非常重要。(C)2009爱思唯尔爱尔兰有限公司。保留所有权利。
Purpose: Although an apparent diffusion coefficient (ADC) value is often used for differential diagnosis of tumours, it varies with scanning parameters. The present study was performed to investigate the influence of imaging parameters, i.e., b value, repetition time (TR) and echo time (TE), on ADC value.Methods: The phantoms were scanned using diffusion weighted imaging (DWI) with changing b values (b = 0-3000 s/mm(2)), TR and TE to determine the influence on ADC. Moreover, ADC of the brain in normal volunteers was determined with varying b values (b = 0-1000 s/mm(2)).Results: Diffusion decay curves were obtained by biexponential fitting in all phantoms. The points where fast and slow components of the biexponential decay crossed were called turning points. The b values of turning points that crossed from the biexponential curve were different in each phantom. The b values of turning points depended on ADC of fast diffusion component. When ADC is calculated using two b values of front and back for the turning point, the ADC value may be different. Therefore, it was necessary to perform calculations by b value until the turning point to obtain the ADC value of the fast component. In addition, b >= 100 was recommended to avoid the influence of perfusion by blood. Furthermore, the choice of long TR and short TE was effective for accurate measurement of ADC.Conclusion: It is important to determine the turning point for measuring ADC. (C) 2009 Elsevier Ireland Ltd. All rights reserved.