Intravoxel incoherent motion (IVIM) imaging is increasingly recognised as an important tool in clinical MRI, where tissue perfusion and diffusion information can aid disease diagnosis, monitoring of patient recovery, and treatment outcome assessment. Currently, the discovery of biomarkers based on IVIM imaging, similar to other medical imaging modalities, is dependent on long preclinical and clinical validation pathways to link observable markers derived from images with the underlying pathophysiological mechanisms. To speed up this process, virtual IVIM imaging is proposed. This approach provides an efficient virtual imaging tool to design, evaluate, and optimise novel approaches for IVIM imaging. In this work, virtual IVIM imaging is developed through a new finite element solver, SpinDoctor-IVIM, which extends SpinDoctor, a diffusion MRI simulation toolbox. SpinDoctor-IVIM simulates IVIM imaging signals by solving the generalised Bloch–Torrey partial differential equation. The input velocity to SpinDoctor-IVIM is computed using HemeLB, an established Lattice Boltzmann blood flow simulator. Contrary to previous approaches, SpinDoctor-IVIM accounts for volumetric microvasculature during blood flow simulations, incorporates diffusion phenomena in the intravascular space, and accounts for the permeability between the intravascular and extravascular spaces. The above-mentioned features of the proposed framework are illustrated with simulations on a realistic microvasculature model.

中文翻译：

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SpinDoctor-IVIM：体素内非相干运动 MRI 的虚拟成像框架


体素内非相干运动 （IVIM） 成像越来越被认为是临床 MRI 中的重要工具，其中组织灌注和弥散信息可以帮助疾病诊断、监测患者康复和治疗结果评估。目前，基于 IVIM 成像的生物标志物的发现与其他医学成像方式类似，依赖于漫长的临床前和临床验证途径，将来自图像的可观察标志物与潜在的病理生理机制联系起来。为了加快这一过程，提出了虚拟 IVIM 成像。这种方法提供了一种高效的虚拟成像工具，用于设计、评估和优化 IVIM 成像的新方法。在这项工作中，虚拟 IVIM 成像是通过新的有限元求解器 SpinDoctor-IVIM 开发的，它扩展了扩散 MRI 仿真工具箱 SpinDoctor。SpinDoctor-IVIM 通过求解广义 Bloch-Torrey 偏微分方程来模拟 IVIM 成像信号。SpinDoctor-IVIM 的输入速度是使用 HemeLB 计算的，HemeLB 是一种成熟的 Lattice Boltzmann 血流模拟器。与以前的方法相反，SpinDoctor-IVIM 考虑了血流模拟过程中的体积微血管系统，结合了血管内间隙的扩散现象，并考虑了血管内和血管外间隙之间的通透性。所提出的框架的上述特征通过对真实微血管系统的模拟来说明。