REFERENCELESS MULTI-COIL RECONSTRUCTION

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 导言： 无参考PRF测温对组织运动具有固有的健壮性，因为不需要减去在加热之前获取的基线相位图像。取而代之的是，通过将多项式与加热区外的相位进行拟合来估计每个单独图像中的背景相位。为此，有必要使相变缓慢，没有间断。在这个项目中，我们演示了一种线圈组合方法，该方法确定并消除了多线圈采集中与线圈相关的相位偏移，并生成具有平滑背景相位的组合图像，可用于无参考方法的温度估计。 方法和讨论：在MatLab中进行多线圈组合和无参考处理。使用最小二乘解确定了N个线圈阵列中任意选择的单个线圈与接收器线圈的相位偏移。一旦确定了各个线圈的差动线圈偏移量，就通过将每个图像与相应的相位偏移量的复共轭相乘来去除该偏移量。经过校正后，可以将数据组合成一幅复杂的图像。对于将结果温度图中的温度不确定性降至最低的组合，可以将相位与幅度平方的加权进行组合。该方法在聚焦超声加热过程中的模体中得到了演示。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Introduction: Referenceless PRF thermometry is inherently robust to tissue motion because the subtraction of a baseline phase image acquired prior to heating is not necessary. Instead, the background phase is estimated in every individual image by fitting a polynomial to the phase outside the heating region. For this it is necessary that the phase vary slowly without discontinuities. In this project, we demonstrate a coil combination method that determines and eliminates the coil dependent phase offset of multi-coil acquisitions and generates combined images with a smooth background phase that can be used for temperature estimation with the referenceless method. Methods and Discussion: The multi-coil combination and referenceless processing was performed in MatLab. Receiver coil phase offsets from an arbitrarily chosen individual coil in an N coil array were determined using a least-squares solution. Once the differential coil offsets of the individual coils were determined, the offset is removed by multiplying each image with the corresponding complex conjugate of the phase offset. After the correction, the data can be combined into a single complex image. For a combination that minimizes the temperature uncertainty in the resulting temperature maps, the phase can be combined with a weighting by the magnitude squared. The method was demonstrated in phantoms during focused ultrasound heating.