Outer volume suppression in steady state sequences (OVSuSS) for percutaneous interventions.

Area of Science:

• Medical Imaging
• Interventional Radiology
• Biomedical Engineering

Background:

• Percutaneous interventions guided by magnetic resonance imaging (MRI) necessitate rapid pulse sequences for real-time needle visualization.
• Imaging needles within moving organs requires acquisition times under 1 second to track trajectory accurately.

Purpose of the Study:

• To develop an MRI method for reducing acquisition time in percutaneous interventions.
• To enable high sampling rates for guiding rigid instruments with enhanced precision.

Main Methods:

• Implemented an MRI technique restricting the field of view to a narrow stripe around the instrument trajectory.
• Incorporated saturation pulses for outer volume suppression within additional repetition time-intervals.
• Tested three sequence variants: spoiled gradient echo, echo-shifted steady state free precession, and balanced steady state free precession.

Main Results:

• Achieved acquisition times in the hundreds of milliseconds, enabling up to six images per second with a 12.5% field of view reduction.
• Demonstrated an average signal-to-suppression ratio of 15.5.
• Validated the method through numerical simulations, phantom experiments, and animal studies.

Conclusions:

• The developed MRI method significantly reduces acquisition time for percutaneous interventions.
• Fast and reliable needle tip visualization is achievable, crucial for robotic-assisted procedures.
• This technique enhances the safety and efficacy of MRI-guided interventions in dynamic environments.