IN-VIVO CONDUCTIVITY IMAGING OF TUMORS WITH MREIT

使用 MREIT 对肿瘤进行体内电导率成像

• 批准号: 7049586
• 负责人: L. Tugan MUFTULER
• 金额: $ 28.83万
• 依托单位: UNIVERSITY OF CALIFORNIA-IRVINE
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-04-06 至 2009-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7049586
• 关键词: breast neoplasm /cancer diagnosis; breast neoplasms; diffusion magnetic resonance imaging; electrical conductance; female; image enhancement; laboratory rat; magnetic resonance imaging; mathematical model; phantom model; sodium ion; tomography

DESCRIPTION (provided by applicant): X-ray mammography is the currently accepted standard for screening breast cancer. However, several other techniques have been developed as an adjunct to X-ray mammography to increase the sensitivity and specificity of the diagnosis. X-ray mammography provides high sensitivity but has a high rate of false-positives. Similarly/the sensitivity of breast MRI has been very high, but the specificity for the detection of abnormalities is variable. Besides the high rate of false positives, some of those techniques also fail to detect the breast cancer in certain cases, such as patients with dense breast tissue, which is common among younger patients. New imaging modalities that offer better specificity may have the potential to reduce the rate of false positives hence eliminate unnecessary biopsies. Several researchers have demonstrated that the electrical properties, specifically the impedance of malignant tissues is significantly different from those of normal and benign tissues. This property has been investigated using various impedance imaging systems. Magnetic Resonance Electrical Impedance Tomography (MREIT) is a new technique to obtain in vivo tissue conductivity images. Objective/Hypothesis: The following two hypotheses will be investigated in this project: 1) Spatial resolution of MREIT will be improved by using a priori information from high resolution MRI. 2) Increase in electrical conductivity in tumors is associated with increased extracellular volume and sodium ion content. Therefore, conductivity images obtained by MREIT method should be highly correlated with sodium-23 and diffusion tensor images obtained with MRI. Specific Aims: 1) Develop and optimize 3D MREIT acquisition and image reconstruction: a) 3D MREIT acquisition; b) 3D FEM analysis; c) Iterative reconstruction to solve the nonlinear equation set; d) Improving MREIT resolution using high-resolution MRI images. 2) Characterization of spatial resolution and contrast of MREIT: Phantom experiments will be carried out to investigate resolution and contrast of MREIT. 3) Sodium and diffusion imaging: Sodium-23 and diffusion tensor images will be collected to investigate ion concentration and mobility and how they relate to conductivity. 4) In vivo imaging of tumors: MREIT, sodium and diffusion tensor imaging will be performed together with Contrast Enhanced-MRI to investigate the potential of these imaging techniques in cancer diagnosis. The MRI based impedance imaging method that we recently developed will be improved using 3D models. Phantom studies will be carried out to investigate image quality including spatial resolution and contrast. Sodium-23 imaging sequence and hardware will be developed and diffusion tensor imaging will be implemented at 4T to investigate ion concentration and mobility. Then, these imaging techniques will be tested on the same group of rats bearing malignant or benign tumors. Dynamic contract enhanced MRI will also be performed on the same animals to investigate tumor structure and how MREIT, sodium and diffusion images correlate with each other. Potential relationships and their complementary usage will be studied to improve quality and possible diagnostic efficacy of MREIT.

描述（由申请人提供）： X射线乳房X光检查是目前公认的筛查乳腺癌的标准。然而，已经开发了几种其他技术作为X射线乳房摄影术的辅助手段，以提高诊断的灵敏度和特异性。X射线乳房摄影术提供高灵敏度，但具有高假阳性率。同样，乳腺MRI的灵敏度非常高，但检测异常的特异性是可变的。除了高假阳性率外，其中一些技术在某些情况下也无法检测到乳腺癌，例如具有致密乳腺组织的患者，这在年轻患者中很常见。新的成像模式，提供更好的特异性可能有潜力降低假阳性率，从而消除不必要的活检。一些研究人员已经证明，恶性组织的电特性，特别是阻抗与正常和良性组织的电特性显著不同。已经使用各种阻抗成像系统研究了此属性。磁共振电阻抗成像（MREIT）是一种获得活体组织电导率图像的新技术。 目的/假设：本项目将研究以下两个假设： 1)利用高分辨率MRI的先验信息将提高MREIT的空间分辨率。 2)肿瘤中电导率的增加与细胞外体积和钠离子含量的增加有关。因此，通过MREIT方法获得的电导率图像应与通过MRI获得的钠-23和扩散张量图像高度相关。 具体目标： 1)开发和优化3D MREIT采集和图像重建：a）3D MREIT采集; B）3D FEM分析; c）迭代重建以求解非线性方程组; d）使用高分辨率MRI图像提高MREIT分辨率。 2)MREIT的空间分辨率和对比度的表征：将进行体模实验以研究MREIT的分辨率和对比度。 3)钠和弥散成像：将收集钠-23和扩散张量图像，以研究离子浓度和迁移率以及它们与电导率的关系。 4)肿瘤的体内成像：MREIT、钠和扩散张量成像将与造影增强MRI一起进行，以研究这些成像技术在癌症诊断中的潜力。 我们最近开发的基于MRI的阻抗成像方法将使用3D模型进行改进。将进行体模研究，以研究图像质量，包括空间分辨率和对比度。将开发钠-23成像序列和硬件，并将在4 T下实施扩散张量成像，以研究离子浓度和迁移率。然后，这些成像技术将在同一组患有恶性或良性肿瘤的大鼠上进行测试。还将对相同动物进行动态对比增强MRI，以研究肿瘤结构以及MREIT、钠和扩散图像如何相互关联。将研究潜在的关系及其互补用途，以提高MREIT的质量和可能的诊断效果。