Department of Radiology, University of Utah, Salt Lake City, Utah 84108, USA.
Magn Reson Med. 2012 Mar;67(3):724-30. doi: 10.1002/mrm.23055. Epub 2011 Jun 23.
Many areas of MR-guided thermal therapy research would benefit from temperature maps with high spatial and temporal resolution that cover a large three-dimensional volume. This article describes an approach to achieve these goals, which is suitable for research applications where retrospective reconstruction of the temperature maps is acceptable. The method acquires undersampled data from a modified three-dimensional segmented echo-planar imaging sequence and creates images using a temporally constrained reconstruction algorithm. The three-dimensional images can be zero-filled to arbitrarily small voxel spacing in all directions and then converted into temperature maps using the standard proton resonance frequency shift technique. During high intensity focused ultrasound heating experiments, the proposed method was used to obtain temperature maps with 1.5 mm × 1.5 mm × 3.0 mm resolution, 288 mm × 162 mm × 78 mm field of view, and 1.7 s temporal resolution. The approach is validated to demonstrate that it can accurately capture the spatial characteristics and time dynamics of rapidly changing high intensity focused ultrasound-induced temperature distributions. Example applications from MR-guided high intensity focused ultrasound research are shown to demonstrate the benefits of the large coverage fully three-dimensional temperature maps, including characterization of volumetric heating trajectories and near- and far-field heating.
许多磁共振引导热疗研究领域都将受益于具有高时空分辨率、覆盖大三维体积的温度图。本文描述了一种可实现这些目标的方法，适用于可接受温度图回溯重建的研究应用。该方法从改进的三维分段回波平面成像序列中获取欠采样数据，并使用受时间约束的重建算法创建图像。三维图像可以在所有方向上零填充到任意小的体素间距，然后使用标准的质子共振频率偏移技术将其转换为温度图。在高强度聚焦超声加热实验中，该方法用于获取分辨率为 1.5mm×1.5mm×3.0mm、视野为 288mm×162mm×78mm、时间分辨率为 1.7s 的温度图。该方法经过验证，可准确捕获高强度聚焦超声诱导的快速变化温度分布的空间特征和时间动态。展示了从磁共振引导高强度聚焦超声研究中获得的示例应用，以展示大覆盖全三维温度图的优势，包括体积加热轨迹以及近场和远场加热的特性化。
