A spiral-based volumetric acquisition for MR temperature imaging.
Authors: Fielden SW, Feng X, Zhao L, Miller GW, Geeslin M, Dallapiazza RF, Elias WJ, Wintermark M, Butts Pauly K, Meyer CH
To develop a rapid pulse sequence for volumetric MR thermometry. 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. 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. 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.
Introduction
Purpose
Thermal ablation
Study Objective
To develop a rapid pulse sequence for volumetric MR thermometry.
Animal model / Human subject
Swine (pig); strain: None; age: None; sex: None
Disease model
Healthy
Outcomes and Safety
Summary of Outcomes
Spiral MRI trajectories—particularly retraced spiral-in/out (RIO) and also spiral-out—provided accurate volumetric MR thermometry with preserved focal spot geometry and no focal spot shift, whereas low-bandwidth Cartesian trajectories produced substantial focal spot shift. The RIO stack-of-spirals 3D sequence achieved real-time 4D thermometry in vivo (swine brain) with update times of 2.9–3.3 s and comparable temperature measurements and temporal stability.
Duration of biological effect
2.9–3.3 seconds
Safety-related matter
No safety concerns or adverse effects are mentioned in the paper; an in vivo swine brain model was used but no adverse events are reported.
Brain Region
Ultrasound Parameters
Focal Characteristics
Focal depth: None; Focal length: None; Aperture size: None
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