A Method for Measuring Orientation Within a Magnetic Resonance Imaging Scanner Using Gravity and the Static Magnetic...

Area of Science:

• Medical Imaging
• Biomedical Engineering
• Neuroimaging

Background:

• Subject motion in MRI brain imaging degrades image clarity.
• Current orientation measurement methods have limitations in range, temporal resolution, and ease of use.
• Existing techniques often require bulky apparatus or external reference frames.

Purpose of the Study:

• To propose and evaluate VectOrient, a novel method for MRI subject orientation measurement.
• To address challenges posed by existing orientation tracking systems in MRI.
• To develop a system compatible with MRI environments and capable of real-time motion correction.

Main Methods:

• Developed VectOrient using vector observations of gravity and the MRI scanner's static magnetic field.
• Utilized a prototype device with an accelerometer, magnetometer, and angular rate sensor.
• Tested with phantom scans and evaluated dynamic performance for prospective motion correction.

Main Results:

• VectOrient achieved comparable results to rigid body registration with deviations less than 0.8 degrees.
• Demonstrated potential for prospective motion correction with rapid orientation changes (peak 20 degrees/sec).
• Orientation updates achieved with latency less than 12.7 ms, including rapid sensor signal computation (<1 ms).

Conclusions:

• VectOrient offers a promising solution for accurate and efficient MRI subject orientation measurement.
• The method enhances MRI imaging workflow by overcoming limitations of existing techniques.
• The system's capabilities extend to quantifying subject respiration and heart rates.