这项研究的目的是提出脂肪参考质子共振频率偏移(PRFS)方法的双步迭代温度估计(DITE),以提高含脂肪组织温度估计的准确性和精度。
使用具有多个脂肪峰的脂肪-水信号模型同时估计温度,脂肪/水强度和T2*,和字段偏移。在DITE,模型拟合采用交替的两步最小化来实现。估计的温度图在两步最小化之间平滑,这被认为是提高温度精度的最重要步骤。通过蒙特卡罗模拟评估了DITE的性能,脂肪/水幻影,和离体棕色脂肪组织实验,然后与以前的脂肪参考质子共振频率偏移方法的性能进行比较。
在具有平滑温度曲线的脂肪/水幻影实验中,DITE估算的温度与温度计结果一致,并且比以前的脂肪参考质子共振频率偏移方法具有更好的准确性和精度。在棕色脂肪组织加热实验中,平均平均误差,SD,和RMS误差为-0.08ºC,0.46ºC,和0.56ºC,分别,在感兴趣区域内的所有测量值。
我们提出的DITE方法在温度曲线的平滑分布下,提高了脂肪分数在20%至80%之间的组织中温度测量的准确性和精度,代表了一种简单的脂肪参考测温方法。
The aim of this study was to propose dual-step iterative temperature estimation (DITE) of a fat-referenced proton resonance frequency shift (PRFS) method to improve both the accuracy and precision of temperature estimations in fat-containing tissues.
A fat-water signal model with multiple fat peaks was used to simultaneously estimate the temperature, fat/water intensity and T 2 ∗ , and field offset. In DITE, model fitting was implemented with alternating 2-step minimizations. The estimated temperature map was smoothed between the 2-step minimizations, which is considered to be the most important step for improving the temperature precision. The performance of DITE was evaluated with a Monte Carlo simulation, fat/water phantoms, and ex vivo brown adipose tissue experiments and then compared with the performance of previous fat-referenced proton resonance frequency shift methods.
In fat/water phantom experiment with a smooth temperature profile, the temperatures estimated by DITE are consistent with the thermometer results and present a better accuracy and precision than those of previous fat-referenced proton resonance frequency shift methods. In the brown adipose tissue heating experiment, the average mean error, SD, and RMS error were -0.08ºC, 0.46ºC, and 0.56ºC, respectively, over all of the measurements within the region of interest.
Our proposed DITE method improves both the accuracy and precision of temperature measurements in tissues with fat fractions between 20% and 80% under smooth distribution of the temperature profile and represents a simple fat-referenced thermometry method.