Lebret Anna, Lévy Simon, Freund Patrick, Callot Virginie, Seif Maryam
Spinal Cord Injury Center, Balgrist University Hospital, Zurich, Switzerland.
Aix-Marseille Univ, CNRS, CRMBM, Marseille, France.
Imaging Neurosci (Camb). 2025 Feb 10;3. doi: 10.1162/imag_a_00468. eCollection 2025.
Intravoxel incoherent motion (IVIM) measurements allow to probe tissue microcirculation non-invasively. Spinal cord perfusion has been shown to be altered following different neurological pathologies. A non-invasive imaging protocol to assess perfusion in the cervical cord is, therefore, clinically relevant. This work aimed at assessing the reliability of IVIM parameters sensitive to perfusion changes in the cervical cord by determining the test-retest variability across subjects and different post-processing fitting algorithms. IVIM test-retest scans were acquired in the cervical cord (C1-C3) of 10 healthy subjects on a 3T MRI scanner, with a 15-minute break in-between. IVIM parameters, including microvascular volume fraction ( ), pseudo-diffusion coefficient ( ), blood flow-related coefficient ( ), and diffusion coefficient ( ), were derived using voxel-wise and region of interest (ROI)-wise fits. The reliability of each IVIM parameter was determined with coefficients of variation (CV), intraclass correlation coefficients (ICC), Bland-Altman analysis, and linear regression. To assess the effects of the different fitting approaches, a two-way repeated-measures analysis of variance (ANOVA) was conducted on the CVs calculated across fitting algorithms. Mean CVs of IVIM parameters calculated across subjects using the voxel-wise fit were lower in the white matter (WM) and grey matter (GM): (WM: 2.6% to 15.6%; GM: 2.2% to 16.4%) compared with those calculated using the ROI-wise fit approach (WM: 4.5% to 32.2%; GM: 3.4% to 53.4%). The voxel-wise fit in the WM yielded higher ICC values (good-to-excellent, 0.71-0.97) compared to the ROI-wise fit approach (poor-to-excellent, 0.49-0.90). IVIM parameters, derived using the voxel-wise fitting approach, demonstrated a high reliability in the cervical cord. Results highlight the high variability of IVIM parameter values depending on the fitting approach, underlining the importance of characterizing the reliability of IVIM acquisition and fitting configuration in the relevant organ of interest. Robust IVIM metrics using a voxel-wise one-step approach, observed across scans and subjects, can facilitate studies targeting perfusion impairment and pave the way to future clinical trials assessing perfusion impairment as a potential quantitative biomarker.
体素内不相干运动（IVIM）测量能够以非侵入性方式探测组织微循环。业已表明，在不同神经病理学状态下脊髓灌注会发生改变。因此，一种用于评估颈髓灌注的非侵入性成像方案具有临床相关性。本研究旨在通过确定受试者间以及不同后处理拟合算法的重测变异性，评估对颈髓灌注变化敏感的IVIM参数的可靠性。在一台3T磁共振成像（MRI）扫描仪上，对10名健康受试者的颈髓（C1 - C3）进行IVIM重测扫描，两次扫描之间间隔15分钟。IVIM参数，包括微血管容积分数（ ）、伪扩散系数（ ）、血流相关系数（ ）和扩散系数（ ），通过体素逐点拟合和感兴趣区域（ROI）逐点拟合得出。使用变异系数（CV）、组内相关系数（ICC）、布兰德 - 奥特曼分析和线性回归来确定每个IVIM参数的可靠性。为了评估不同拟合方法的影响，对跨拟合算法计算的CV进行双向重复测量方差分析（ANOVA）。与使用ROI逐点拟合方法计算的结果相比，在白质（WM）和灰质（GM）中，使用体素逐点拟合在受试者间计算的IVIM参数平均CV更低：（WM：2.6%至15.6%；GM：2.2%至16.4%），而使用ROI逐点拟合方法计算的结果为（WM：4.5%至32.2%；GM：3.4%至53.4%）。与ROI逐点拟合方法（差至优，0.49 - 0.90）相比，WM中体素逐点拟合产生了更高的ICC值（良好至优秀，0.71 - 0.97）。使用体素逐点拟合方法得出的IVIM参数在颈髓中显示出高可靠性。结果突出了IVIM参数值因拟合方法而异的高度变异性，强调了在相关感兴趣器官中表征IVIM采集和拟合配置可靠性的重要性。在扫描和受试者中观察到的使用体素逐点一步法的稳健IVIM指标，能够促进针对灌注损伤的研究，并为未来评估灌注损伤作为潜在定量生物标志物的临床试验铺平道路。
