REFERENCELESS PRF THERMOMETRY WITH MULTI-ECHO PROCESSING

这个子项目是利用由NIH/NCRR资助的中心拨款提供的资源的许多研究子项目之一。子项目和调查员(PI)可能从另一个NIH来源获得了主要资金，因此可能会出现在其他CRISE条目中。列出的机构是针对中心的，而不一定是针对调查员的机构。前言：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健壮性，因为不需要减去加热前获取的基线相位图像。取而代之的是，在来自加热区周围的帧感兴趣区域(ROI)的每个单独图像中估计背景相位。对于前列腺消融术中的温度监测，我们建议扩展到无参考测温，允许在水和脂肪之间存在相间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，其中所有三个回波在一次采集中都被采集，以提高热消融期间温度监测的时间分辨率。结果表明，由于热分布的空间分辨率较低，获取一幅低分辨率的图像(平面上1.7-1.9 mm)就足够了。然而，为了可视化解剖结构，需要更高的分辨率。在所提出的脉冲序列中，为了在不降低时间分辨率的情况下重建低分辨率温度图像和高分辨率解剖图像，每个回波在k空间的覆盖范围是不同的。该方法在体模和活体犬前列腺消融术中得到了验证。

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.