Motion-compensated real-time MR thermometry augmented by tracking coils.

Area of Science:

• Medical Imaging
• Interventional Radiology
• Biomedical Engineering

Background:

• Accurate temperature monitoring is crucial for MRI-guided thermal therapies.
• Motion artifacts can significantly degrade the accuracy of MR thermometry.
• Existing methods often struggle to compensate for complex motion during procedures.

Purpose of the Study:

• To develop and evaluate a real-time MR thermometry method using proton resonant frequency (PRF).
• To incorporate a novel motion compensation technique utilizing a linear phase model and active tracking coils.
• To assess the method's performance in the presence of both in-plane and through-plane motion.

Main Methods:

• A 6F catheter with tracking coils and RF ablation tip was used in ex vivo bovine liver experiments on a 1.5T scanner.
• A real-time MR acquisition scheme with interleaved catheter tracking and multislice imaging was implemented.
• Periodic and irregular motions were induced to simulate physiological conditions, and temperature maps were generated during RF ablation.

Main Results:

• The proposed method achieved a temporal window of ~380 ms per slice and tracking.
• Tracking errors were less than 1 mm in the x-y plane for both irregular and periodic motions.
• The thermometry method demonstrated comparable accuracy (σ = 1.10 vs. 1.04°C) to the multi-baseline method under various motion conditions.

Conclusions:

• The novel MR thermometry method effectively compensates for motion using catheter-based tracking coils and a linear phase model.
• This technique shows promise for reliable real-time MR thermometry in MRI-guided thermal therapies.
• The method offers accurate temperature monitoring, crucial for optimizing treatment efficacy and safety.