Optimization of self-reference thermometry using complex field estimation
Optimization of self-reference thermometry using complex field estimation
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DOI：
10.1002/mrm.21016
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发表时间：
2006-10-01
影响因子：
3.3
通讯作者：
Keserci, Bilgin
中科院分区：
文献类型：
--
作者：
Kuroda, Kagayaki;Kokuryo, Daisuke;Keserci, Bilgin
无参考或自参考测温法是一种使用基线相位来绘制感兴趣区域（ROI）中的温差的技术，该基线相位通过外推周围区域中的场进行估计（RFE）并从测量场中减去估计基线来估计。在本工作中，提出并优化了一种基于复场估计的自参考技术，该技术使用包含复值系数的二维多项式。具有高斯轮廓相位分布的数值模拟表明，ROI半径必须是高斯函数的标准偏差（SD）的2.3-2.5倍，以便将误差保持在峰值相位变化的8%以下。ROI和RFE之间的面积比必须大于2.0，以保持误差水平。基于模拟、体模和志愿者实验，将具有两个空间维度的独立优化的多项式阶数的基于复合物的方法与使用相似阶数优化策略的基于相位的方法进行比较。当相位展开未被移除时，基于复合物的方法似乎是有用的。另外，基于相位的方法得到了具有较少多项式阶数的等效结果。
Referenceless, or self-reference, thermometry is a technique for mapping temperature differences in the region of interest (ROI) using the baseline phase estimated by extrapolating the field in the surrounding region for estimation (RFE) and subtracting the estimated baseline from the measured field. In the present work a self-reference technique based on complex field estimation using 2D polynomials comprising complex-valued coefficients was proposed and optimized. Numerical simulations with a Gaussian-profiled phase distribution demonstrated that the ROI radius had to be 2.3-2.5 times the standard deviation (SD) of the Gaussian function in order to keep the error below 8% of the peak phase change. The area ratio between the ROI and the RFE had to be larger than 2.0 to maintain the error level. Based on the simulations, and phantom and volunteer experiments, the complex-based method with independently optimized polynomial orders for the two spatial dimensions was compared with the phase-based method using the similar-order optimization strategy. The complex-based method appeared to be useful when phase unwrapping was not removed. Otherwise, the phase-based method yielded equivalent results with less polynomial orders.