Department of Radiological Sciences, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90024, USA.
J Neurooncol. 2013 Apr;112(2):257-66. doi: 10.1007/s11060-013-1057-y. Epub 2013 Jan 24.
Fluid attenuated inversion recovery (FLAIR) MRI sequences have become an indispensible tool for defining the malignant boundary in patients with brain tumors by nulling the signal contribution from cerebrospinal fluid allowing both regions of edema and regions of non-enhancing, infiltrating tumor to become hyperintense on resulting images. In the current study we examined the utility of a three-dimensional double inversion recovery (DIR) sequence that additionally nulls the MR signal associated with white matter, implemented either pre-contrast or post-contrast, in order to determine whether this sequence allows for better differentiation between tumor and normal brain tissue. T1- and T2-weighted, FLAIR, dynamic susceptibility contrast (DSC)-MRI estimates of cerebral blood volume (rCBV), contrast-enhanced T1-weighted images (T1+C), and DIR data (pre- or post-contrast) were acquired in 22 patients with glioblastoma. Contrast-to-noise (CNR) and tumor volumes were compared between DIR and FLAIR sequences. Line profiles across regions of tumor were generated to evaluate similarities between image contrasts. Additionally, voxel-wise associations between DIR and other sequences were examined. Results suggested post-contrast DIR images were hyperintense (bright) in regions spatially similar those having FLAIR hyperintensity and hypointense (dark) in regions with contrast-enhancement or elevated rCBV due to the high sensitivity of 3D turbo spin echo sequences to susceptibility differences between different tissues. DIR tumor volumes were statistically smaller than tumor volumes as defined by FLAIR (Paired t test, P = 0.0084), averaging a difference of approximately 14 mL or 24 %. DIR images had approximately 1.5× higher lesion CNR compared with FLAIR images (Paired t test, P = 0.0048). Line profiles across tumor regions and scatter plots of voxel-wise coherence between different contrasts confirmed a positive correlation between DIR and FLAIR signal intensity and a negative correlation between DIR and both post-contrast T1-weighted image signal intensity and rCBV. Additional discrepancies between FLAIR and DIR abnormal regions were also observed, together suggesting DIR may provide additional information beyond that of FLAIR.
磁共振液体衰减反转恢复（FLAIR）序列已成为通过使脑脊液信号失活来定义脑肿瘤患者恶性边界的不可或缺的工具，从而使水肿区域和无增强浸润性肿瘤区域在图像上呈现高信号。在本研究中，我们检查了三维双反转恢复（DIR）序列的实用性，该序列还可以使与白质相关的 MR 信号失活，无论是在对比前还是对比后，以确定该序列是否可以更好地区分肿瘤和正常脑组织。在 22 例胶质母细胞瘤患者中采集了 T1 和 T2 加权、FLAIR、动态对比增强磁共振成像（DSC）脑血容量（rCBV）估计值、对比增强 T1 加权图像（T1+C）和 DIR 数据（对比前或对比后）。比较 DIR 和 FLAIR 序列之间的对比噪声比（CNR）和肿瘤体积。生成跨越肿瘤区域的线轮廓以评估图像对比度之间的相似性。此外，还检查了体素间 DIR 与其他序列之间的关联。结果表明，对比后 DIR 图像在空间上与 FLAIR 高信号相似的区域呈高信号（亮），在具有对比增强或 rCBV 升高的区域呈低信号（暗），这是由于 3D 涡轮自旋回波序列对不同组织之间的磁化率差异具有高灵敏度。与 FLAIR 定义的肿瘤体积相比，DIR 肿瘤体积统计上较小（配对 t 检验，P = 0.0084），平均差异约为 14 mL 或 24%。与 FLAIR 图像相比，DIR 图像的病变 CNR 约高 1.5 倍（配对 t 检验，P = 0.0048）。跨越肿瘤区域的线轮廓和不同对比度之间体素相干性的散点图证实了 DIR 和 FLAIR 信号强度之间的正相关，以及 DIR 和对比后 T1 加权图像信号强度和 rCBV 之间的负相关。还观察到 FLAIR 和 DIR 异常区域之间的其他差异，这表明 DIR 可能提供 FLAIR 之外的额外信息。
