Biopsy needle artifact localization in MRI-guided robotic transrectal prostate intervention

Area of Science:

• Medical Imaging
• Robotics
• Biomedical Engineering

Background:

• Robotic systems enhance MRI-guided needle placement in the prostate.
• Titanium needles, common in biopsies, are not directly visible on MRI scans.
• Titanium needles produce magnetic susceptibility artifacts, complicating accurate visualization.

Purpose of the Study:

• To quantitatively assess the relationship between true titanium needle position and its artifact in MRI.
• To understand how needle artifacts influence targeting accuracy in MRI-guided interventions.

Main Methods:

• Quantitative analysis of titanium biopsy needle position versus artifact position in MRI.
• Evaluation of artifact characteristics, including extension, bending, and axial displacement.

Main Results:

• The titanium needle tip artifact extended up to 9 mm beyond the true needle tip.
• Artifacts showed a tendency to bend towards the scanner's main magnetic field (B0).
• Mean axial displacements of the artifact were 0.38 mm (frequency encoding) and 0.32 mm (phase encoding).

Conclusions:

• Accurate targeting in MRI-guided prostate interventions requires accounting for titanium needle artifact characteristics.
• The observed artifact extension and bending can introduce significant targeting errors.
• This study provides crucial data for improving the precision of MRI-guided robotic needle placement systems.