Estimating Accurate Target Coordinates with Magnetic Resonance Images by Using Multiple Phase-Encoding Directions...

Area of Science:

• Neurosurgery
• Medical Imaging
• Radiology

Background:

• Image distortion in magnetic resonance (MR) imaging can compromise the accuracy of stereotactic procedures.
• Precise targeting is crucial for interventions like deep brain stimulation.

Purpose of the Study:

• To evaluate methods for improving target coordinate accuracy in MR-guided stereotactic procedures.
• To assess the impact of phase-encoding direction on MR image distortion.

Main Methods:

• Acquired 5 image sets from 30 patients undergoing deep brain stimulation: stereotactic CT, T2WI, and T1WI in right-to-left (RL) and anterior-to-posterior (AP) phase-encoding directions.
• Analyzed anterior and posterior commissure coordinates using CT as a reference to quantify phase-encoding-related distortion.
• Compared two methods for predicting CT coordinates using MR data: parallel translation and selective axis choice based on phase-encoding direction.

Main Results:

• Right-to-left (RL) directed MR images showed positive x-axis deviations (0.51-0.58 mm) compared to CT.
• Anterior-to-posterior (AP) directed MR images exhibited negative y-axis deviations (0.44-0.59 mm) compared to CT.
• Both predictive methods (parallel translation and selective axis choice) equally improved CT coordinate prediction using MR data; selective axis choice may be more clinically practical.

Conclusions:

• Acquiring MR images with multiple phase-encoding directions is essential for accurate stereotactic targeting.
• Selecting image axes based on phase-encoding direction significantly enhances coordinate accuracy in MR-guided stereotactic procedures.
• This approach offers improved precision for neurosurgical interventions requiring accurate targeting.