Volumetric MRI thermometry using a three-dimensional stack-of-stars echo-planar imaging pulse sequence

Area of Science:

• Magnetic Resonance Imaging
• Biomedical Engineering
• Neuroscience

Background:

• Accurate brain temperature monitoring is essential for understanding neurological processes and guiding therapeutic interventions.
• Existing methods often lack the required spatiotemporal resolution or volumetric coverage for comprehensive brain analysis.

Purpose of the Study:

• To develop and validate a novel three-dimensional (3D) echo-planar imaging (EPI) sequence for proton resonance frequency-shift temperature imaging.
• To achieve fine spatiotemporal resolution for measuring temperature across a large brain volume.

Main Methods:

• Implementation of a 3D stack-of-stars EPI sequence with radial sampling and golden angle spacing at 3 Tesla.
• Reconstruction of temperature maps using sensitivity encoding (SENSE) and k-space hybrid methods.
• Acquisition of in vivo temperature maps in the brain and phantom sonication experiments.

Main Results:

• Achieved in vivo temperature precision with standard deviation less than 1°C at scan times as low as 0.75 seconds.
• Demonstrated whole-brain coverage, albeit with a 48% higher temperature standard deviation compared to 2D methods at similar frame rates.
• Produced artifact-free phantom temperature maps with dynamic scan times down to 0.38 seconds; k-space hybrid reconstructions showed better tolerance to acceleration.

Conclusions:

• 3D stack-of-stars EPI temperature mapping offers a viable method for volumetric brain coverage with high spatiotemporal resolution.
• This technique advances the capability for non-invasive brain temperature monitoring.