A spiral-based volumetric acquisition for MR temperature imaging

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Medical Physics
• Biomedical Engineering

Background:

• Volumetric MR thermometry is crucial for monitoring temperature during thermal therapies.
• Current methods can be limited by speed and accuracy.
• Developing rapid pulse sequences is essential for real-time temperature monitoring.

Purpose of the Study:

• To develop and evaluate a rapid pulse sequence for volumetric MR thermometry.
• To compare the performance of different imaging trajectories for MR thermometry.

Main Methods:

• Simulations assessed Cartesian, spiral-out, and retraced spiral-in/out (RIO) trajectories for temperature deviation, focal spot distortion, and shift.
• The RIO trajectory was implemented for 3D stack-of-spirals imaging on a real-time platform.
• In vivo evaluation in a swine brain model compared the 3D sequence with a standard 2D sequence.

Main Results:

• Spiral trajectories demonstrated no focal spot shift, unlike Cartesian trajectories.
• The 3D RIO sequence provided real-time 4D thermometry monitoring with an update time of 2.9-3.3 seconds.
• In vivo results showed comparable maximum and mean temperatures between the 3D and 2D methods.

Conclusions:

• Spiral imaging, particularly RIO, significantly speeds up volumetric MR thermometry.
• The developed 3D sequence enables efficient real-time 4D temperature monitoring.
• This technique holds promise for enhanced precision in thermal therapies.