Schading-Sassenhausen Simon, Seif Maryam, Weiskopf Nikolaus, Freund Patrick
Spinal Cord Injury Center, Balgrist University Hospital, University of Zurich, Zurich, Switzerland.
Department of Neurophysics, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany.
Imaging Neurosci (Camb). 2024 Jul 15;2. doi: 10.1162/imag_a_00225. eCollection 2024.
Synthetic MRI offers the advantage of reducing acquisition time and enhancing flexibility through the reconstruction of various contrast weightings from a single set of MRI scans. However, the use of synthetic T-weighted (synT-w) MRI can lead to potentially biased measurements of the cross-sectional area (CSA) in the spinal cord when compared to conventionally acquired T-weighted MRI. This disparity can have implications for comparability and sensitivity of MRI in assessing disease progression or treatment effects in neurodegenerative spinal cord disorders. Thus, this study aimed at improving the accuracy (i.e., difference between synthetic and acquired MRI) of cervical cord CSA measurements (C1-C3 level) based on synT-w MRI implementing a longitudinal data set acquired from 23 acute spinal cord injury (SCI) patients and 21 healthy controls over 2 years. Moreover, the validity of using synT-w MRI for tracking cervical cord atrophy following SCI over 2 years was verified. SynT-w images were reconstructed from quantitative maps of proton density, longitudinal, and effective transverse relaxation rates derived from a multi-parameter mapping protocol. The results showed a minimal bias of -0.31 mm(-0.5%) in CSA measurements based on synT-w compared to acquired MRI. Estimates of atrophy rates and average CSA were comparable between synthetic and acquired MRI. A sample size estimation for detecting treatment effects on CSA atrophy after 2 years following SCI revealed that the required sample size is reduced by 13.5% using synT-w instead of acquired MRI. This study shows high accuracy of synT-w MRI and demonstrates its applicability in clinical studies for optimizing long MRI protocols.
合成磁共振成像（MRI）具有减少采集时间并通过从单组MRI扫描重建各种对比度加权来增强灵活性的优势。然而，与传统采集的T加权MRI相比，使用合成T加权（synT-w）MRI可能会导致脊髓横截面积（CSA）测量出现潜在偏差。这种差异可能会影响MRI在评估神经退行性脊髓疾病的疾病进展或治疗效果时的可比性和敏感性。因此，本研究旨在基于synT-w MRI提高颈髓CSA测量（C1-C3水平）的准确性（即合成MRI与采集的MRI之间的差异），该研究采用了从23例急性脊髓损伤（SCI）患者和21名健康对照者在2年期间获取的纵向数据集。此外，还验证了使用synT-w MRI跟踪SCI后2年颈髓萎缩的有效性。synT-w图像是从多参数映射协议得出的质子密度、纵向和有效横向弛豫率的定量图重建而来的。结果显示，与采集的MRI相比，基于synT-w的CSA测量偏差极小，为-0.31 mm（-0.5%）。合成MRI与采集的MRI之间的萎缩率估计值和平均CSA具有可比性。一项关于检测SCI后2年对CSA萎缩治疗效果的样本量估计显示，使用synT-w而非采集的MRI时，所需样本量减少了13.5%。本研究显示了synT-w MRI的高精度，并证明了其在优化长MRI方案的临床研究中的适用性。
