Is Weisskoff model valid for the correction of contrast agent extravasation with combined T1 and T2* effects in dynamic susceptibility contrast MRI?
Is Weisskoff model valid for the correction of contrast agent extravasation with combined T1 and T2* effects in dynamic susceptibility contrast MRI?
复制标题
DOI：
10.1118/1.3534197
复制
发表时间：
2011-02-01
期刊：
影响因子：
3.8
通讯作者：
Hsu, Yuan-Yu
中科院分区：
文献类型：
--
作者：
Liu, Ho-Ling;Wu, Yi-Ying;Hsu, Yuan-Yu
目的：Weisskoff模型已被广泛应用于校正动态敏感性对比(DSC)-MRI信号中造影剂泄漏的T-1效应。本研究旨在修改Weisskoff模型，以纳入造影剂外渗的T-1和T-2效应。方法：提出了一个双室模型，并将其应用于原始Weisskoff模型中，以描述测量DSC-MRI信号中造影剂泄漏引起的T-1和T-2联合效应。通过计算机模拟来评估T-1和T-2优势对成像参数、场强、基线T-1和泄漏严重程度的依赖性。采用改进的Weisskoff模型对3例脑肿瘤患者的相对脑血容量（rCBV）图进行校正，以证明其应用价值。结果：所得方程与原模型具有相同的数学形式，但拟合常数K-2的表达式不同。这个新参数可以是正值，也可以是负值。计算机模拟结果显示，较长的TE、较高的场强、较短的基线T-1和更多的造影剂提取，更可能是T-2优势。临床数据与模型拟合良好，K-2阳性表明T-1优势，低估rCBV； K-2阴性表明T-2优势，高估rCBV。正常脑组织的K-2值比增强肿瘤的K-2值分布范围小得多。灰质（GM）校正后与未校正的归一化CBV （nCBV）之比在1.04 ~ 1.05之间，说明校正前后nCBV保持相当稳定。结论：本研究提出了一种改进的Weisskoff模型，该模型能够解释造影剂外渗在DSC-MRI中的T-1和T-2显性效应。要使K-2参数成为血管渗透性的定量指标，还需进一步发展。(C) 2011年美国医学物理学家协会。(DOI: 10.1118/1.3534197)
Purpose: The Weisskoff model has been widely applied for correcting the T-1 effect of the contrast agent leakage in the measured dynamic susceptibility contrast (DSC)-MRI signals. This study aimed to modify the Weisskoff model for the inclusion of both T-1 and T-2 effects of the contrast agent extravasation.Methods: A two-compartment model was proposed and implemented into the original Weisskoff model to describe the combined T-1 and T-2 effects from the contrast agent leakage in the measured DSC-MRI signals. A computer simulation was performed to evaluate the dependence of T-1 versus T-2 dominance on imaging parameter, field strength, baseline T-1, and severity of the leakage. The modified Weisskoff model was employed to correct the relative cerebral blood volume (rCBV) maps in three patients with brain tumors to demonstrate its use.Results: The resultant equation had the same mathematical form as the original model, but with a different expression for the fitting constant K-2. This new parameter can be of either a positive or a negative value. Results of the computer simulation showed more probable T-2 dominance with longer TE, higher field strength, shorter baseline T-1, and greater extraction of the contrast agent. Clinical data were well fitted by the model, with a positive K-2 indicating T-1 dominance and underestimated rCBV and a negative K-2 indicating T-2 dominance and overestimated rCBV. The K-2 values of normal-appearing brain tissues were distributed in a much smaller range than the K-2 values of enhancing tumors. The ratios of corrected over uncorrected normalized CBV (nCBV) for gray matter (GM) were in the range between 1.04 and 1.05, meaning that the nCBV remained rather stable before and after correction. The ratios for the tumors were 0.65, 0.42, and 2.81, either much smaller or greater than the ratios for GM.Conclusions: This study proposed a modified Weisskoff model that was able to explain both T-1 and T-2 dominant effects of the contrast agent extravasation in DSC-MRI. Further development is needed to make the K-2 parameter a quantitative indicator of the vessel permeability. (C) 2011 American Association of Physicists in Medicine. [DOI: 10.1118/1.3534197]