Siemens Healthcare K.K., Tokyo, Japan.
Siemens Healthcare K.K., Tokyo, Japan.
Eur J Radiol. 2019 Jul;116:160-164. doi: 10.1016/j.ejrad.2019.04.019. Epub 2019 Apr 29.
Cerebrospinal fluid (CSF) and white matter (WM) signal suppression techniques allow better visualization of both WM and gray matter (GM) lesions in such disorders as multiple sclerosis and epilepsy. Recently, a technique, FLuid And White matter Suppression "FLAWS", has been proposed at 3 T based on the magnetization-prepared with two rapid gradient echoes (MP2RAGE) sequence. In this study, the FLAWS-MP2RAGE pulse sequence was compared with a double inversion recovery turbo spin echo (DIR-TSE) sequence at 7 T. Twenty-two healthy volunteers were examined. Isotropic spatial resolution of 1 mm and a scan time of approximately 6 min were chosen due to a restricted clinical schedule. Homogeneity of CSF and WM signal suppression was compared with GM signal as an intensity reference. Volumes of GM visualization and specific absorption rates (SARs) were compared using Wilcoxon-rank sum tests with Bonferroni-Holm correction for multiple comparisons. WM-to-GM signal ratios in FLAWS-MP2RAGE images were significantly lower than DIR-TSE (median: 24.5% vs 59.0%, P < 0.0001), whereas CSF-to-GM signal ratios in FLAWS-MP2RAGE were significantly higher than DIR-TSE (57.1% vs 38.3%, P = 0.0001). Ranges of the signal ratios between 20 and 80 percentiles were lower in FLAWS-MP2RAGE than DIR-TSE for WM (24.1% vs 37.2%, P < 0.0001) but were higher in FLAWS-MP2RAGE compared with DIR-TSE for CSF (80.8% vs 63.0%, P = 0.0001). Pixels of low GM signal (< 20% of the median) were mainly distributed at the skull base, and these low signal GM volume ratios were lower in FLAWS-MP2RAGE than DIR-TSE (2.27% vs 6.18%, P < 0.0001). Median SAR in sixteen subjects was 2.5 times higher in DIR-TSE than in FLAWS-MP2RAGE. FLAWS-MP2RAGE showed superior and more homogenous WM signal suppression, better GM visualization at the skull base and lower SAR compared with DIR-TSE, suggesting superiority of FLAWS-MP2RAGE at 7 T.
脑脊液（CSF）和白质（WM）信号抑制技术可改善多发性硬化症和癫痫等疾病中 WM 和灰质（GM）病变的可视化。最近，一种基于磁化准备双快速梯度回波（MP2RAGE）序列的技术，即“FLuid And White matter Suppression “FLAWS”，在 3T 中被提出。在这项研究中，在 7T 时，将 FLAWS-MP2RAGE 脉冲序列与双反转恢复涡轮自旋回波（DIR-TSE）序列进行了比较。22 名健康志愿者接受了检查。由于临床时间限制，选择了各向同性空间分辨率为 1mm 和扫描时间约 6min。通过比较 GM 信号作为强度参考，比较了 CSF 和 WM 信号抑制的均匀性。使用 Wilcoxon-rank sum 检验并进行了 Bonferroni-Holm 多重比较校正，比较了 GM 可视化体积和特定吸收率（SAR）。FLAWS-MP2RAGE 图像中的 WM 与 GM 信号的比值明显低于 DIR-TSE（中位数：24.5% vs 59.0%，P<0.0001），而 FLAWS-MP2RAGE 中的 CSF 与 GM 信号的比值明显高于 DIR-TSE（57.1% vs 38.3%，P=0.0001）。FLAWS-MP2RAGE 中 WM 的信号比值 20%至 80%的范围低于 DIR-TSE（24.1% vs 37.2%，P<0.0001），而 FLAWS-MP2RAGE 中 CSF 的信号比值高于 DIR-TSE（80.8% vs 63.0%，P=0.0001）。GM 信号低（<20%中位数）的像素主要分布在颅底，并且颅底的 FLAWS-MP2RAGE 中低信号 GM 体积比 DIR-TSE 低（2.27% vs 6.18%，P<0.0001）。在 16 名受试者中，DIR-TSE 的平均 SAR 比 FLAWS-MP2RAGE 高 2.5 倍。FLAWS-MP2RAGE 在 7T 时显示出优越的、更均匀的 WM 信号抑制、更好的颅底 GM 可视化和更低的 SAR，与 DIR-TSE 相比具有优势。
