Advancing the Detection of Human Disease at 7 Tesla MRI

推进 7 特斯拉 MRI 人类疾病的检测

• 批准号: 9010618
• 负责人: Sossena Wood
• 金额: $ 4.36万
• 依托单位: UNIVERSITY OF PITTSBURGH AT PITTSBURGH
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-12-01 至 2016-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9010618
• 关键词: Address; Adult; Algorithms; Biological; Brain Injuries; Characteristics; Clinical; Communities; Computer Simulation; Computer software; Detection; Early Diagnosis; Early Intervention; Electromagnetics; Elements; Evaluation; Geometry; Goals; Head; Health; Human; Human body; Image; Intervention; Magnetic Resonance Imaging; Maps; Measurement; Methods; Modeling; Neurodegenerative Disorders; Noise; Patients; Performance; Physiologic pulse; Property; Research; Resolution; Safety; Shapes; Signal Transduction; Slice; Statistical Data Interpretation; Study models; Symptoms; System; Techniques; Temperature; Testing; Time; Tissue Expansion; Tissues; Variant; Water; Work; absorption; base; design; expectation; experience; human disease; improved; in vivo; magnetic field; novel; parallel computer; particle; premature; radiofrequency; research study; simulation; tool; transmission process

 DESCRIPTION (provided by applicant): Ultra-high field (UHF) MRI (e 7 Tesla) promise of detecting human disease within the human body continues to grow [4]. However, there are several issues experienced at higher field strengths that hinder its clinical feasibility. These specific UHF MRI challenges addressed by this work are: (1) achieving magnetic field homogeneity, (2) reducing the global/local specific absorption rate (SAR) in biological tissue that are not subject dependent and (3) addressing concerns regarding the unclear RF safety assurance of the multi-transmit experiment due to inappropriate electromagnetic models for the estimation of the SAR at UHF. Such challenges limit the intervention and detection of human disease for 7T. This work focuses on tackling this issue for the human head. The limitations drastically hinder clinicians from using UHF MRI for early detection and intervention of neurodegenerative diseases and symptoms of brain damage in patients. The main goal of this work is to provide solutions through hardware and software to the clinical use of UHF MRI and master the understanding of its limitations. The specific aims of this project are: Aim 1: Develop an Anatomically Detailed Human Head Phantom to Evaluate B1+, SAR, and B1+ Temperature Mapping through Simulation and Experimental Studies at 7T. An anatomically detailed human head phantom is designed to have eight (8) refillable tissue compartments that hold electromagnetically equivalent biological properties of the conductivity, permittivity, and T1 measurements at 7T. The model's computational simulations are produced to evaluate B1, SAR, and B1 temperature ++ mapping. Lastly, experimental studies of the model are compared to both the simulation and in-vivo B1 + mapping of the head phantom and the human head in which the phantom was originally modeled. Aim 2: Design, Develop and Evaluate a Nonlinear B1+ Shimming MRI Parallel Transmission (PTx) Optimization Algorithm to achieve the B1+ uniformity through Simulation and Experimental Studies at 7T. A novel method of RF excitation pulses are produced from a Parallel Transmission (PTx) tool to perform B1 shimming on various regions of the human body using various nonlinear algorithms (i.e. particle + swarm). The system is designed to reduce the required time to address the limitations though parallel computing techniques using software and hardware (i.e. GPUs). Aim 3: Evaluate the Performance of Multi-Row Transceiver Arrays using Parallel Transmission and/or B1+ Shimming for B1+ maps and SAR maps analysis through Simulation and Experimental Studies at 7T. In order that this is achieved, computational electromagnetic modeling for a variation of anatomically detailed human head models (contractions/expansions and tissue addition/subtractions) within an RF coil (8- ch and 16-ch) is performed. Novel RF excitation pulses obtained from B1 shimming in a region are used to provide acceptable local and average SAR across the entire volume of various human head models. To test its real application, we analyze and compare the B1 field and SAR maps associated with each of the RF array elements for all the head models. Lastly, we perform in-vivo studies of acceptable RF excitation pulses on subjects to validate Tx array. At the completion of this project, it is our expectation that the combination of results collected from aims 1, 2, and 3 will further the UHF MRI community's understanding of 7T imaging. Progress in this proposed work will allow 7T MR imaging to be more enhanced in its ability to detect human diseases by yielding a more uniform 7T MR image.

 描述（由适用提供）：超高场（UHF）MRI（E 7 TESLA）在人体内检测人类疾病的承诺继续增长[4]。但是，在较高的现场优势下遇到了几个问题，这阻碍了其临床可行性。这项工作解决的这些特定的UHF MRI挑战是：（1）实现磁场同质性，（2）在生物组织中降低全球/局部特异性滥用率（SAR） 与受试者不相关，并且（3）由于不适当的电磁模型来估计UHF处的SAR，因此解决了对多跨度实验不清楚的RF安全性的担忧。这种挑战限制了7T人类疾病的干预和检测。这项工作着重于解决人类的问题。这些局限性极大地阻碍了临床医生使用UHF MRI进行早期检测和干预神经退行性疾病和患者脑损伤的症状。这项工作的主要目标是通过硬件和软件提供解决方案，以临床使用UHF MRI，并掌握对其局限性的理解。该项目的具体目的是：目标1：通过7T的模拟和实验研究，开发一个解剖详细的人头幻影来评估B1+，SAR和B1+温度映射。解剖详细的人头幻影旨在具有八（8）个可再填充的组织室，可在7T处具有电磁上等效的生物学特性。该模型的计算模拟是为评估B1，SAR和B1温度++映射的。最后，将模型的实验研究与最初建模的幻影的模拟和体内B1 +映射进行了比较。 AIM 2：设计，开发和评估非线性B1+ Shimming MRI平行传输（PTX）优化算法，以通过7T的模拟和实验研究实现B1+均匀性。使用各种非线性算法（即粒子 + swarm）在人体的各个区域（即，粒子 + swarm）在人体的各个区域中执行B1的刺激性脉冲的一种新型方法。该系统旨在减少目标3：使用平行传输和/或B1+弹跳来评估多排收发器阵列的性能，用于B1+ MAPS和SAR MAPS分析，通过7T的仿真和实验研究。为了实现这一目标，对RF线圈（8-CH和16-CH）进行了解剖详细的人头模型（收缩/扩展和组织添加/减法）的变化的计算电磁建模。从一个区域中的B1弹跳获得的新型RF刺激脉冲用于在整个人类头模型的整个体积中提供可接受的局部和平均SAR。为了测试其实际应用，我们分析和比较了与所有头部模型的每个RF阵列元素相关的B1字段和SAR地图。最后，我们对受试者对可接受的RF兴奋性脉冲进行验证TX阵列的可接受的RF兴奋性脉冲进行研究。该项目完成后，我们期望从目标1、2和3收集的结果组合将进一步进一步，将进一步了解UHF MRI社区对7T成像的理解。在这项提出的工作中的进展将使7T MR成像通过产生更均匀的7T MR图像来提高其检测人类疾病的能力。

项目成果

A comprehensive electromagnetic evaluation of an MRI anthropomorphic head phantom.

• DOI: 10.1002/nbm.4441
• 发表时间: 2021-03
• 期刊: NMR in biomedicine
• 影响因子: 2.9
• 作者: Wood S;Santini T;Krishnamurthy N;Martins T;Farhat N;Ibrahim TS
• 通讯作者: Ibrahim TS

Correction: Design and fabrication of a realistic anthropomorphic heterogeneous head phantom for MR purposes.

修正：设计和制造用于 MR 目的的逼真的拟人异质头部模型。

• DOI: 10.1371/journal.pone.0192794
• 发表时间: 2018
• 期刊: PloS one
• 影响因子: 3.7
• 作者: Wood,Sossena;Krishnamurthy,Narayanan;Santini,Tales;Raval,ShaileshB;Farhat,Nadim;Holmes,JohnAndy;Ibrahim,TamerS
• 通讯作者: Ibrahim,TamerS