场强切换 MRI 识别 0.2T 以下的小面积缺血性中风

Field-Cycling MRI for Identifying Minor Ischemic Stroke Below 0.2 T.

机构信息

From the Aberdeen Biomedical Imaging Centre (V.M., P.J.R., E.F., D.J.L., L.M.B.) and Institute of Medical Sciences (M.J.M.), University of Aberdeen, Polwarth Building, Foresterhill, Aberdeen AB25 2ZD, United Kingdom; Institute of Medical Engineering, Graz University of Technology, Graz, Austria (O.M.); and Acute Stroke Unit, Aberdeen Royal Infirmary, Aberdeen, United Kingdom (G.G.G.).

出版信息

Radiology. 2024 Aug;312(2):e232972. doi: 10.1148/radiol.232972.

DOI:10.1148/radiol.232972

PMID:39189899

Abstract

Background Field-cycling imaging (FCI) is a new technology developed at the University of Aberdeen that measures change in T1 relaxation time constant of tissues over a range of low magnetic field strengths (0.2-200 mT) by rapidly switching between different fields during the pulse sequence. This provides new sources of contrast, including some invisible to clinical MRI scanners, and may be a useful alternative imaging modality for stroke. Purpose To test whether a prototype whole-body FCI scanner can be used to identify infarct regions in patients with subacute ischemic stroke. Materials and Methods This prospective study screened consecutive adult patients admitted to a single center stroke unit from February 2018 to March 2020 and April to December 2021. Included participants with confirmed ischemic stroke underwent FCI 1-6 days after ictus. FCI scans were obtained at four to six evolution fields between 0.2 mT and 0.2 T, with five evolution times from 5 to 546 msec. T1 maps were generated. The Wilcoxon signed-rank test was used to compare infarct region and contralateral unaffected brain, and Spearman rank correlation was used to examine associations between infarct to contralateral tissue contrast ratio and field strengths. Two independent readers blinded to clinical images rated the FCI scans. Results Nine participants (mean age, 62 years ± 16 [SD]; all male) successfully completed FCI. FCI scans below 0.2 T exhibited hyperintense T1 regions corresponding to the infarct region identified at baseline imaging, visually confirmed with 86% interrater agreement (Cohen κ = 0.69). Infarct to contralateral tissue contrast ratio increased as magnetic field decreased between 0.2 mT and 0.2 T ([24] = -0.68; < .001). T1 dispersion slopes differed between infarct and unaffected tissues (median, 0.23 [IQR, 0.18-0.37] vs 0.35 [IQR, 0.27-0.43]; = .03). Conclusion Whole-brain FCI can be used to identify subacute ischemic stroke by T1 relaxation mechanisms at field strengths as low as 0.2 mT. Research Registry no. 1813 Published under a CC BY 4.0 license.

摘要

背景场频成像（FCI）是阿伯丁大学开发的一项新技术，通过在脉冲序列期间在不同场之间快速切换，测量组织 T1 弛豫时间常数在一系列低磁场强度（0.2-200 mT）下的变化。这提供了新的对比源，包括临床 MRI 扫描仪无法检测到的对比源，并且可能是中风的一种有用的替代成像方式。

目的测试原型全身 FCI 扫描仪是否可用于识别亚急性缺血性中风患者的梗塞区域。

材料和方法这项前瞻性研究筛选了 2018 年 2 月至 2020 年 3 月和 2021 年 4 月至 12 月期间在单一中心卒中病房连续入院的成年患者。纳入的经确认患有缺血性中风的参与者在中风后 1-6 天接受 FCI 检查。在 0.2 mT 和 0.2 T 之间的四个到六个演化场中获得 FCI 扫描，演化时间从 5 到 546 msec 不等。生成 T1 图谱。使用 Wilcoxon 符号秩检验比较梗塞区域和对侧未受影响的大脑，并使用 Spearman 秩相关检验检验梗塞与对侧组织对比率与场强之间的相关性。两位独立的读者对临床图像进行了盲法评分。

结果 9 名参与者（平均年龄 62 岁±16[标准差]；均为男性）成功完成了 FCI。低于 0.2 T 的 FCI 扫描显示与基线成像中确定的梗塞区域相对应的 T1 高信号区域，视觉确认的两位读者间的一致性为 86%（Cohen κ = 0.69）。随着磁场从 0.2 mT 降至 0.2 T，梗塞与对侧组织的对比率增加（[24] = -0.68； <.001）。梗塞和未受影响组织之间的 T1 弥散斜率不同（中位数，0.23[IQR，0.18-0.37]与 0.35[IQR，0.27-0.43]； =.03）。

结论通过在低至 0.2 mT 的场强下使用 T1 弛豫机制，全身 FCI 可用于识别亚急性缺血性中风。

研究注册号 1813 发表于 CC BY 4.0 许可下。