Magnetic resonance imaging versus computed tomography for target localization in functional stereotactic neurosurgery

Area of Science:

• Neurosurgery
• Radiology
• Medical Imaging

Background:

• Accurate stereotactic target localization is crucial for neurosurgical procedures like ventrolateral thalamotomy and posteroventral pallidotomy.
• Both magnetic resonance imaging (MRI) and computed tomography (CT) are utilized for image-guided surgery, each with distinct strengths in anatomical visualization.

Purpose of the Study:

• To compare the consistency and accuracy of target localization between MRI and CT for stereotactic pallidotomy and thalamotomy.
• To evaluate the clinical significance of differences in coordinate localization derived from MRI versus CT.

Main Methods:

• Analyzed 93 neurosurgical procedures (78 pallidotomies, 15 thalamotomies) in 83 patients.
• Calculated and compared stereotactic coordinates for anterior commissure, posterior commissure, and surgical targets using both MRI- and CT-derived images.

Main Results:

• Mean differences between MRI- and CT-derived target coordinates were statistically significant but small (e.g., -0.41 mm on x-axis, -0.34 mm on z-axis).
• Mean absolute differences for the target were within 1.25 mm in three dimensions, with distances exceeding 4 mm in only 1-2% of cases.
• Mean 3D distances for fiducial landmarks (anterior and posterior commissures) were 1.65 mm, with occasional larger deviations (>4 mm).

Conclusions:

• While statistically significant differences exist, MRI and CT provide largely consistent target localization for pallidotomy and thalamotomy.
• MRI offers superior anatomical resolution, supporting its use as a standalone imaging modality for target localization in these procedures.
• Institutional validation is recommended to ensure accuracy and manage potential larger deviations in coordinate localization.