1 Department of Radiation Oncology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.
2 Department of Radiation Oncology, University Hospital Tübingen, Tübingen, Germany.
Technol Cancer Res Treat. 2017 Aug;16(4):470-481. doi: 10.1177/1533034616656310. Epub 2016 Jul 14.
The difference in the resonance frequency of water and methylene moieties of lipids quantifies in magnetic resonance spectroscopy the absolute temperature using a predefined calibration curve. The purpose of this study was the investigation of peak evaluation methods and the magnetic resonance spectroscopy sequence (point-resolved spectroscopy) parameter optimization that enables thermometry during deep hyperthermia treatments.
Different Lorentz peak-fitting methods and a peak finding method using singular value decomposition of a Hankel matrix were compared. Phantom measurements on organic substances (mayonnaise and pork) were performed inside the hyperthermia 1.5-T magnetic resonance imaging system for the parameter optimization study. Parameter settings such as voxel size, echo time, and flip angle were varied and investigated.
Usually all peak analyzing methods were applicable. Lorentz peak-fitting method in MATLAB proved to be the most stable regardless of the number of fitted peaks, yet the slowest method. The examinations yielded an optimal parameter combination of 8 cm voxel volume, 55 millisecond echo time, and a 90° excitation pulse flip angle.
The Lorentz peak-fitting method in MATLAB was the most reliable peak analyzing method. Measurements in homogeneous and heterogeneous phantoms resulted in optimized parameters for the magnetic resonance spectroscopy sequence for thermometry.
利用预设的校准曲线，通过磁共振光谱中水和亚甲基部分的共振频率差异来量化绝对温度。本研究的目的是研究能够在深部热疗期间进行测温的峰评估方法和磁共振光谱序列（点分辨光谱）参数优化。
比较了不同的洛伦兹峰拟合方法和使用汉克尔矩阵奇异值分解的峰查找方法。在 1.5T 磁共振成像系统内对有机物质（蛋黄酱和猪肉）进行了体模测量，以进行参数优化研究。改变并研究了体素大小、回波时间和翻转角等参数设置。
通常所有的峰分析方法都是适用的。MATLAB 中的洛伦兹峰拟合方法被证明是最稳定的，无论拟合峰的数量如何，但速度最慢。检查得出的最佳参数组合为 8cm 体素体积、55 毫秒回波时间和 90°激发脉冲翻转角。
MATLAB 中的洛伦兹峰拟合方法是最可靠的峰分析方法。在均匀和非均匀体模中的测量得出了用于测温的磁共振光谱序列的优化参数。
