Department of Medical Physics and Biomedical Engineering, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran; Department of Neuroimaging and Analysis, Imam Khomeini Hospital Complex, Tehran University of Medical Sciences, Tehran, Iran.
Iranian Center of Neurological Research (ICNR), Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran.
Phys Med. 2021 May;85:87-97. doi: 10.1016/j.ejmp.2021.03.039. Epub 2021 May 10.
Oxygen extraction fraction (OEF) can be a factor to identify brain tissue's disability in epileptic patients. This study aimed to assess the OEF's level measurement in refractory epileptic patients (REPs) using a quantitative susceptibility mapping (QSM) method and to determine whether the OEF parameters change.
QSM-OEF maps of 26 REPs and 16 healthy subjects were acquired using 3T MRI with a 64-channel coil. Eighteen regions-of-interest (ROIs) were chosen around the cortex in one appropriate slice of the brain and the mean QSM-OEF for each ROI was obtained. The correlations of QSM-OEF among different clinical characteristics of the disease, as well as between the patients and normal subjects, were also investigated.
QSM-OEF was shown to be significantly higher in REPs (44.9 ± 5.8) than that in HS (41.9 ± 6.2) (p < 0.05). Mean QSM-OEF was statistically lower in the ipsilateral side (44.5 ± 6.6) compared to the contralateral side (46.4 ± 6.8) (P < 0.01). QSM-OEF was illustrated to have a strong positive correlation with the attack duration (r = 0.6), and a moderate negative correlation with the attack frequency (r = -0.3). Using an optimized support vector machine algorithm, we could predict the disease in subjects having abnormal OEF values in the brain-selected-ROIs with sensitivity, specificity, AUC, and the precision of 0.96, 1, 0.98, and 1, respectively.
The results of this study revealed that QSM-OEF of the REPs' brain is higher than that of HS, which indicates that QSM-OEF is associated with disease activity.
氧摄取分数（OEF）可作为识别癫痫患者脑组织功能障碍的因素。本研究旨在使用定量磁化率映射（QSM）方法评估难治性癫痫患者（REP）的 OEF 水平，并确定 OEF 参数是否发生变化。
使用配备 64 通道线圈的 3T MRI 采集 26 例 REP 和 16 例健康受试者的 QSM-OEF 图。在大脑的一个适当切片中选择皮层周围的 18 个感兴趣区（ROI），并获得每个 ROI 的平均 QSM-OEF。还研究了 QSM-OEF 与疾病不同临床特征之间的相关性，以及患者与正常受试者之间的相关性。
REP 的 QSM-OEF（44.9±5.8）明显高于 HS（41.9±6.2）（p<0.05）。与对侧（46.4±6.8）相比，同侧（44.5±6.6）的平均 QSM-OEF 统计学上更低（P<0.01）。QSM-OEF 与发作持续时间呈强正相关（r=0.6），与发作频率呈中度负相关（r=-0.3）。使用优化的支持向量机算法，我们可以以 0.96、1、0.98 和 1 的灵敏度、特异性、AUC 和精度预测大脑选定 ROI 中 OEF 值异常的受试者中的疾病。
本研究结果表明，REP 大脑的 QSM-OEF 高于 HS，这表明 QSM-OEF 与疾病活动有关。
