Ricchi Mattia, Axford Aaron, McGing Jordan, Shinozaki Ayaka, Yeung Kylie, Mills Rebecca, Zaccagna Fulvio, Tyler Damian J, Testa Claudia, Grist James T
Department of Computer Sciences, University of Pisa, Pisa, Italy.
National Institute of Nuclear Physics (INFN), Bologna Division, Bologna, Italy.
Sci Rep. 2025 Jul 30;15(1):27769. doi: 10.1038/s41598-025-12777-y.
Diffusion-weighted imaging (DWI) is a key contrast mechanism in MRI which allows for the assessment of microstructural properties of brain tissues by measuring the displacement of water molecules. Several diffusion models, including the tensor (DTI), kurtosis (DKI), and neurite orientation dispersion and density imaging (NODDI), are commonly used in both research and clinical practice. However, there is currently no standardized method for validating the stability and repeatability of these models over time. This study evaluates the use of a DTI phantom as a standard reference for diffusion MRI model validation. The phantom, along with four healthy volunteers, was scanned repeatedly on different days to assess repeatability and stability. The acquired data were fitted to the diffusion models, with repeatability assessed in the phantom using the coefficient of variation (CoV), while stability in vivo was assessed using the repeatability coefficient (RC). The phantom was consecutively scanned eight times to investigate the impact of gradient coil heating on measurement consistency. Results showed that the phantom provided a highly reproducible reference, with CoVs below 5% across repeated and consecutive acquisitions, confirming the robustness of the diffusion models. In vivo, the low RCs indicated that the models remained stable over time, despite potential physiological variability. This study highlights the essential role of phantoms in diffusion MRI research, providing a reference framework for model validation. Future research will expand on this work to a multi-center study to assess inter-scanner variability, potentially incorporating the phantom into calibration protocols to standardize diffusion MRI measurements across different MRI systems.
扩散加权成像（DWI）是磁共振成像（MRI）中的一种关键对比机制，它通过测量水分子的位移来评估脑组织的微观结构特性。包括张量（DTI）、峰度（DKI）和神经突方向分散与密度成像（NODDI）在内的几种扩散模型在研究和临床实践中都常用。然而，目前尚无标准化方法来验证这些模型随时间的稳定性和可重复性。本研究评估了使用DTI体模作为扩散MRI模型验证的标准参考。该体模与四名健康志愿者在不同日期反复进行扫描，以评估可重复性和稳定性。将采集的数据拟合到扩散模型中，在体模中使用变异系数（CoV）评估可重复性，而在体内使用重复性系数（RC）评估稳定性。对体模连续扫描八次，以研究梯度线圈加热对测量一致性的影响。结果表明，该体模提供了高度可重复的参考，在重复和连续采集过程中CoV均低于5%，证实了扩散模型的稳健性。在体内，低RC表明尽管存在潜在的生理变异性，但模型随时间保持稳定。本研究强调了体模在扩散MRI研究中的重要作用，为模型验证提供了参考框架。未来的研究将把这项工作扩展到多中心研究，以评估不同扫描仪之间的变异性，可能将体模纳入校准方案，以标准化不同MRI系统的扩散MRI测量。
