NON-INVASIVE IMAGING OF INTERNAL BODY TEMPERATURE USING MRI FOR THERMAL THERAPIES

本研究的主要目的是建立一种在各种热疗条件下进行无创体内温度成像的方法。基于2000年元素技术的发展和评估，我们专注于开发使用天然代谢物信号的内部参考（换句话说，自参考）温度成像技术。为了提高回波平面光谱成像（EPSI）技术在磁场不均匀条件下的光谱质量，对EPSI技术进行了改进，使其具有线扫描能力（LSEPSI）。还改进了3 T-MRI中用于小动物的鸟笼线圈的生产技术，以提高线圈的发射和接收规格。这些改进为20 mM柠檬酸盐体模以及10 mM NAA（N-乙酰天冬氨酸）体模生成了清晰的内部参考温度分布变化图。利用LSEP进行兔脑温度成像的实验研究 ...更多信息 SI成功地使用天然丰度（~ 7 mM）的NAA使温度分布变化可视化。与相位映射方法不同，这种内部参考技术不需要逐像素相减。这意味着该技术对扫描间运动或扫描间磁化率变化更耐用。对人类志愿者大脑的单独测量表明，水-NAA化学位移既不是恒定的，也不是均匀的;它因位置和个体而异。在温度变化5℃时，其差值可达0.05ppm。众所周知，脑组织中的内部脑温度几乎是均匀的，因此差异是由于温度以外的因素。绝对脑温度成像似乎仍然是一个遥远的目标，总体而言，本项目2年的研究已经建立了使用温度成像的相位映射方法（外部参考方法）和LSEPSI方法（内部参考方法）的温度变化成像。用于甚高场（VHF，3 T）MRI的动物线圈技术也已完成。少

Our primary aim of this research project was to establish the methodology of non-invasive internal-body temperature imaging under variety of the thermal therapies. Based on the development and assessment of the elemental technologies in 2000, we have focused on the development of the internally referenced (in other word self-referenced) temperature imaging technique using naturally contained metabolite signals. The echo planar spectroscopic imaging (EPSI) technique was modified as to have line scan capability (LSEPSI) to improve the spectrum quality under existence of the magnetic field inhomogeneity. The production technique of the birdcage coil for small animals in 3T-MRI was also refined to improve the coils transmission and reception specifications. These improvement yielded clear, internally referenced temperature distribution change maps for a 20 mM citrate phantom as well as a 10 mM NAA (N-Acetyl Aspartic acid) phantom. Our trial for a rabbit brain temperature imaging using LSEP … More SI was successful to visualize the temperature distribution change using NAA of a natural abundance (-7 mM). This internally-referenced technique does not require the pixel-by-pixel subtraction unlike the phase mapping approach. This means that the technique is more durable against the inter-scan motion or the inter-scan susceptibility change.Separate measurements for human volunteers' brains demonstrated that the water-NAA chemical shift is neither constant nor homogeneous ; It differs by locations and by individuals. The difference reaches as 0.05 ppm which corresponds to 5℃ of temperature variation. It is known that the internal brain temperature is almost homogeneous in a brain tissues, and therefore the difference is due to a factor other than temperature. Absolute brain temperature imaging still seems to be a far goal.Overall, the 2-years research in this project has established temperature change imaging using the phase mapping method (externally referenced approach) and the LSEPSI approach (internally referenced approach) of temperature imaging. The animal coil technology for a very high field (VHF, 3T) MRI has also been completed. Less