A spiral‐based volumetric acquisition for MR temperature imaging. Issue 6 (8th November 2017) - Fielden, Samuel W.
Abstract : Purpose: To develop a rapid pulse sequence for volumetric MR thermometry. Methods: Simulations were carried out to assess temperature deviation, focal spot distortion/blurring, and focal spot shift across a range of readout durations and maximum temperatures for Cartesian, spiral‐out, and retraced spiral‐in/out (RIO) trajectories. The RIO trajectory was applied for stack‐of‐spirals 3D imaging on a real‐time imaging platform and preliminary evaluation was carried out compared to a standard 2D sequence in vivo using a swine brain model, comparing maximum and mean temperatures measured between the two methods, as well as the temporal standard deviation measured by the two methods. Results: In simulations, low‐bandwidth Cartesian trajectories showed substantial shift of the focal spot, whereas both spiral trajectories showed no shift while maintaining focal spot geometry. In vivo, the 3D sequence achieved real‐time 4D monitoring of thermometry, with an update time of 2.9–3.3 s. Conclusion: Spiral imaging, and RIO imaging in particular, is an effective way to speed up volumetric MR thermometry. Magn Reson Med 79:3122–3127, 2018. © 2017 International Society for Magnetic Resonance in Medicine.