Virtual Phantoms

This folder contains 5 patient-derived virtual phantoms. Virtual phantoms were developed from patient scan data to provide flexible, programmable, and quantiative ground truths for reconstruction testing while maintaining realistic models of patient phyisology and bolus propogation.<br>Parameters of pharmacokinetic models were fit from patient data and used with patient images to define virtual phantoms. These phantoms were implemented as a stored set of parameters and evaluation functions and are designed as inputs to a virtual scan simulator also developed for this project. Code for the virtual scanner can be found, along with a demo, at https://github.com/tyo8/ECA_Demo .<br>The phantoms used in this experiment modeled noisy acquisition with signal from three different classes of sources; vessel, lesion, and background. Vessel and lesion signal components come from distinct models but a single procedure; all signal components are additive.<br>Vessels and lesions were segmented from patient images and perfusion maps were created from ultrafast data, using a flow constraint method developed by Chengyue Wu at the University of Texas (reference).<br>In addition to the virtual phantoms, each MATLAB file in this folder contains a minimal complete set of inputs to run the phantom through the virtual scanner, including virtual MRI acquisition parameters (e.g., TR and TE) and an acquisition sequence.

本文件夹包含5例患者来源的虚拟体模（virtual phantom）。虚拟体模基于患者扫描数据构建，可为重建测试提供灵活、可编程且可量化的基准真值，同时保留患者生理学与对比剂团块传播的真实模型。
药代动力学模型（pharmacokinetic model）的参数由患者数据拟合所得，并结合患者影像用于定义虚拟体模。此类体模以参数集与评估函数的形式存储，被设计为本项目同期开发的虚拟扫描模拟器（virtual scan simulator）的输入。虚拟扫描器的代码与演示程序可于 https://github.com/tyo8/ECA_Demo 获取。
本实验使用的体模对带噪声的采集过程进行建模，其信号源自三类不同来源：血管、病灶与背景。血管与病灶的信号组分虽分属不同模型，但遵循统一的生成流程；所有信号组分均为叠加形式。
血管与病灶均从患者影像中分割得到，灌注图（perfusion map）由超快速扫描数据生成，采用了得克萨斯大学吴承悦（Chengyue Wu）开发的血流约束方法（详见参考文献）。
除虚拟体模外，本文件夹内的每个MATLAB文件均包含一套极简完整的输入参数集，可通过虚拟扫描模拟器运行该体模，其中涵盖虚拟MRI采集参数（如TR与TE）及采集序列。