Peng Yuhong, Zou Chao, Qiao Yangzi, Tie Changjun, Wan Qian, Jiang Rui, Cheng Chuanli, Liang Dong, Zheng Hairong, Li Faqi, Liu Xin
State Key Laboratory of Ultrasound Engineering in Medicine, Chongqing Key Laboratory of Biomedical Engineering, Co-Founded by Chongqing and the Ministry of Science and Technology, College of Biomedical Engineering, Chongqing Medical University, 153 Box, 1 Yixueyuan Road, Yuzhong District, Chongqing, 400016, China.
Paul C Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, 1068 Xueyuan Blvd, Nanshan District, Shenzhen, 518055, Guangdong, China.
MAGMA. 2018 Dec;31(6):771-779. doi: 10.1007/s10334-018-0692-x. Epub 2018 Jun 14.
Real-time monitoring is important for the safety and effectiveness of high-intensity focused ultrasound (HIFU) therapy. Magnetic resonance imaging is the preferred imaging modality for HIFU monitoring, with its unique capability of temperature imaging. For real-time temperature imaging, higher temporal resolution and larger spatial coverage are needed. In this study, a sequence based on the echo-shifted RF-spoiled gradient echo (GRE) with simultaneous multi-slice (SMS) imaging was designed for fast temperature imaging.
A phantom experiment was conducted to evaluate the accuracy of the echo-shifted sequence using a fluorescent fiber thermometer as reference. The temperature uncertainty of the echo-shifted sequence was compared with the traditional GRE sequence at room temperature through the ex vivo porcine muscle. Finally, the ex vivo porcine liver tissue experiment using HIFU heating was performed to demonstrate that the spatial coverage was increased without decreasing temporal resolution.
The echo-shifted sequence had a better temperature uncertainty performance compared with the traditional GRE sequence with the same temporal resolution. The ex vivo heating experiment confirmed that by combining the SMS technique and echo-shifted sequence, the spatial coverage was increased without decreasing the temporal resolution while maintaining high temperature measurement precision.
The proposed technique was validated as an effective real-time method for monitoring HIFU therapy.
实时监测对于高强度聚焦超声（HIFU）治疗的安全性和有效性至关重要。磁共振成像因其独特的温度成像能力，是HIFU监测的首选成像方式。对于实时温度成像，需要更高的时间分辨率和更大的空间覆盖范围。在本研究中，设计了一种基于回波偏移射频扰相梯度回波（GRE）并结合同时多切片（SMS）成像的序列用于快速温度成像。
进行了体模实验，以荧光光纤温度计为参考评估回波偏移序列的准确性。通过离体猪肌肉在室温下将回波偏移序列的温度不确定性与传统GRE序列进行比较。最后，进行了使用HIFU加热的离体猪肝组织实验，以证明在不降低时间分辨率的情况下增加了空间覆盖范围。
在相同时间分辨率下，回波偏移序列比传统GRE序列具有更好的温度不确定性性能。离体加热实验证实，通过结合SMS技术和回波偏移序列，在保持高温测量精度的同时，在不降低时间分辨率的情况下增加了空间覆盖范围。
所提出的技术被验证为一种监测HIFU治疗的有效实时方法。
