REFERENCELESS PRF THERMOMETRY WITH MULTI-ECHO PROCESSING

该子项目是利用NIH/NCRR资助的中心赠款提供的资源的许多研究子项目之一。子项目和研究者（PI）可能从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。所列机构为中心机构，不一定是研究者机构。简介：无参考质子共振频率（PRF）移位测温法对组织运动具有固有的鲁棒性，因为在加热之前不需要减去所采集的基线相位图像。相反，在来自加热区域周围的感兴趣的帧区域（ROI）的每个单独的图像中估计背景相位。对于前列腺消融过程中的热监测，我们提出了一种扩展到无参考测温，允许在水和脂肪之间存在相位不连续的情况下进行温度估计。 方法和讨论：在这里，我们开发了一种脉冲序列，其中所有三个回波都在一次采集中采集，以提高热消融过程中温度监测的时间分辨率。已经表明，由于加热分布的相对低的空间分辨率，获取用于温度监测的低分辨率图像（平面内1.7-1.9 mm）是足够的。然而，为了使解剖结构可视化，需要更高的分辨率。在所提出的脉冲序列中，每个回波的k空间覆盖范围不同，以便允许重建低分辨率温度图像和高分辨率解剖图像，而不会降低时间分辨率。该方法在体模和体内犬前列腺消融过程中得到了证实。

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 proton resonance frequency (PRF) shift 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 from a frame region of interest (ROI) surrounding the heating region. For thermal monitoring during prostate ablation, we have proposed an extension to referenceless thermometry that allows temperature estimation in the presence of phase discontinuities between water and fat. Methods and Discussion: Here, we developed a pulse sequence where all three echoes are acquired in a single acquisition for increased temporal resolution of the temperature monitoring during thermal ablation. It has been shown that due to the relatively low spatial resolution of the heating distribution it is sufficient to acquire a low resolution image for temperature monitoring (1.7-1.9 mm in plane). To visualize the anatomical structures, however, higher resolution is desired. In the proposed pulse sequence, each echo¿s k-space coverage varies in order to allow reconstruction of both a low resolution temperature image and a high resolution anatomical image, without a decrease in temporal resolution. The method is demonstrated in phantoms and during in vivo canine prostate ablation.