Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
F. M. Kirby Research Center, Kennedy Krieger Institute, Baltimore, Maryland, USA.
J Magn Reson Imaging. 2018 Feb;47(2):554-564. doi: 10.1002/jmri.25777. Epub 2017 Jun 5.
To investigate pathological changes in the rat brain after pilocarpine-induced status epilepticus using quantitative susceptibility mapping (QSM).
3D multiecho gradient-echo (GRE) data were acquired from ex vivo brains of pilocarpine-injected and age-matched control rats at 11.7T. Maps of R2* and quantitative susceptibility were calculated from the acquired 3D GRE magnitude and phase data, respectively. QSM and R2* maps were compared with Perls' (iron) and Alizarin-red-S (calcium) stainings in the same brains to investigate the pathophysiological basis of susceptibility contrast.
Bilaterally symmetric lesions were detected in reproducible thalamic regions of pilocarpine-treated rats, characterized by hyperintensity in R2* maps. In comparison, quantitative susceptibility maps demonstrated heterogeneous contrast within the lesions, with distinct hyperintense (paramagnetic) and hypointense (diamagnetic) areas. Comparison with histological assessment revealed localized deposits of iron- and calcium-positive granules in thalamic nuclei corresponding to paramagnetic and diamagnetic areas delineated in the susceptibility maps, respectively. Pronounced differences were observed in the lesions between background-corrected phase images and reconstructed susceptibility maps, indicating unreliable differentiation of iron and calcium deposits in phase maps. Multiple linear regression showed a significant association between susceptibility values and measured optical densities (ODs) of iron and calcium in the lesions (R = 0.42, P < 0.001), with a positive dependence on OD of iron and negative dependence on OD of calcium.
QSM can detect and differentiate pathological iron and calcium deposits with high sensitivity and improved spatial accuracy compared to R2* or GRE phase images, rendering it a promising technique for diagnosing thalamic lesions after status epilepticus.
1 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2018;47:554-564.
使用定量磁化率映射（QSM）研究匹鲁卡品诱导癫痫持续状态后大鼠大脑的病理变化。
在 11.7T 下，从匹鲁卡品注射和年龄匹配的对照组大鼠的离体脑中采集 3D 多回波梯度回波（GRE）数据。从采集的 3D GRE 幅度和相位数据中分别计算 R2* 和定量磁化率图。QSM 和 R2* 图与相同脑内的 Perls（铁）和茜素红 S（钙）染色进行比较，以研究磁化率对比的病理生理学基础。
在匹鲁卡品处理的大鼠可重复的丘脑区域检测到双侧对称的病变，表现为 R2* 图中的高信号。相比之下，定量磁化率图显示病变内存在不均匀的对比，具有明显的高信号（顺磁）和低信号（抗磁）区域。与组织学评估的比较显示，在对应于磁化率图中描绘的顺磁和抗磁区域的丘脑核中存在局部铁和钙阳性颗粒沉积。在病变背景校正相位图像和重建磁化率图之间观察到明显的差异，表明相位图中铁和钙沉积的区分不可靠。多元线性回归显示磁化率值与病变中铁和钙的测量光密度（OD）之间存在显著相关性（R = 0.42，P < 0.001），与铁的 OD 呈正相关，与钙的 OD 呈负相关。
与 R2* 或 GRE 相位图像相比，QSM 可以检测和区分病理性铁和钙沉积，具有更高的灵敏度和空间准确性，是诊断癫痫持续状态后丘脑病变的一种很有前途的技术。
1 技术功效：第 1 阶段 J. Magn. Reson. Imaging 2018;47:554-564.
