Frequency-Dependent Conductivity Contrast for Tissue Characterization Using a Dual-Frequency Range Conductivity Mapping Magnetic Resonance Method
Frequency-Dependent Conductivity Contrast for Tissue Characterization Using a Dual-Frequency Range Conductivity Mapping Magnetic Resonance Method
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DOI：
10.1109/tmi.2014.2361689
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发表时间：
2015-02-01
影响因子：
10.6
通讯作者：
Woo, Eung Je
中科院分区：
文献类型：
--
作者：
Kim, Dong-Hyun;Chauhan, Munish;Woo, Eung Je
生物组织的电导率表现出频率依赖行为，这些值在不同的频率可能提供临床有用的诊断信息。磁共振电阻抗断层扫描（MREIT）和磁共振电阻抗断层扫描（MREPT）等基于核磁共振的组织属性映射技术被广泛使用，并在不同频率范围内提供独特的电导率对比信息。最近，提出了一种单次磁共振扫描的低频和高频电导率图像数据采集和重建的新方法。在这项研究中，我们应用这种同时双频范围电导率映射MR方法来评估其在设计的幻影和两个体内动物疾病模型中的实用性。利用改进的自旋回波脉冲序列，获得了双频电导率图像的磁通密度和相位图。利用投影电流密度法从MREIT数据重建低频电导率，利用映射法从MREPT数据重建高频电导率。利用两种不同的电导率模型，通过带孔或不带孔的绝缘膜分离不同的离子浓度，研究了与离子浓度和迁移率相关的频率依赖性电导率的对比机制。以犬脑脓肿和脑缺血为体内模型，评估该方法在两种不同频率下识别新的基于电特性的对比度的能力。同时双频范围电导率映射MR方法提供了与组织内离子浓度和迁移率相关的独特对比信息。这种方法有可能监测疾病状态的动态变化。
Electrical conductivities of biological tissues show frequency-dependent behaviors, and these values at different frequencies may provide clinically useful diagnostic information. MR-based tissue property mapping techniques such as magnetic resonance electrical impedance tomography (MREIT) and magnetic resonance electrical property tomography (MREPT) are widely used and provide unique conductivity contrast information over different frequency ranges. Recently, a new method for data acquisition and reconstruction for low-and high-frequency conductivity images from a single MR scan was proposed. In this study, we applied this simultaneous dual-frequency range conductivity mapping MR method to evaluate its utility in a designed phantom and two in vivo animal disease models. Magnetic flux density and phase map for dual-frequency conductivity images were acquired using a modified spin-echo pulse sequence. Low-frequency conductivity was reconstructed from MREIT data by the projected current density method, while high-frequency conductivity was reconstructed from MREPT data by mapping. Two different conductivity phantoms comprising varying ion concentrations separated by insulating films with or without holes were used to study the contrast mechanism of the frequency-dependent conductivities related to ion concentration and mobility. Canine brain abscess and ischemia were used as in vivo models to evaluate the capability of the proposed method to identify new electrical properties-based contrast at two different frequencies. The simultaneous dual-frequency range conductivity mapping MR method provides unique contrast information related to the concentration and mobility of ions inside tissues. This method has potential to monitor dynamic changes of the state of disease.