Department of Physics and Astronomy, University of Georgia, Athens, GA, USA.
Phys Med Biol. 2011 Dec 21;56(24):N307-20. doi: 10.1088/0031-9155/56/24/N02. Epub 2011 Nov 18.
In magnetic resonance (MR) imaging, the most widely used and accurate method for measuring temperature is based on the shift in proton resonance frequency (PRF). However, inter-scan motion and bulk magnetic field shifts can lead to inaccurate temperature measurements in the PRF-shift MR thermometry method. The self-reference PRF-shift MR thermometry method was introduced to overcome such problems by deriving a reference image from the heated or treated image, and approximates the reference phase map with low-order polynomial functions. In this note, a new approach is presented to calculate the baseline phase map in self-reference PRF-shift MR thermometry. The proposed method utilizes the phase gradient to remove the phase unwrapping step inherent to other self-reference PRF-shift MR thermometry methods. The performance of the proposed method was evaluated using numerical simulations with temperature distributions following a two-dimensional Gaussian function as well as phantom and in vivo experimental data sets. The results from both the numerical simulations and experimental data show that the proposed method is a promising technique for measuring temperature.
在磁共振（MR）成像中，最广泛使用和准确的测量温度的方法是基于质子共振频率（PRF）的移动。然而，在 PRF 移动磁共振测温法中，扫描间运动和体磁场偏移可能导致不准确的温度测量。自参考 PRF 移动磁共振测温法通过从加热或处理的图像中得出参考图像，并使用低阶多项式函数来近似参考相位图，从而克服了这些问题。在本说明中，提出了一种新的方法来计算自参考 PRF 移动磁共振测温中的基线相位图。所提出的方法利用相位梯度来去除其他自参考 PRF 移动磁共振测温方法固有的相位展开步骤。使用温度分布遵循二维高斯函数以及体模和体内实验数据集的数值模拟评估了该方法的性能。数值模拟和实验数据的结果表明，该方法是一种很有前途的测温技术。
