Abstract
Object Proton resonance frequency shift thermometry is sensitive to breathing motion that leads to incorrect phase differences. In thiswork, a novel velocity-sensitive navigator technique for triggering MR thermometry image acquisition is presented. Materials and methods A segmented echo planar imaging pulse sequence was modified for velocity-triggered temperature mapping. Trigger events were generated when the estimated velocity value was less than 0.2 cm/s during the slowdown phase in parallel to the velocity-encoding direction. To remove remaining high-frequency spikes from pulsation in real time, a Kalman filter was applied to the velocity navigator data. A phantom experiment with heating and an initial volunteer experiment without heating were performed to show the applicability of this technique. Additionally, a breath-hold experiment was conducted for comparison. Results A temperature rise of T = +37.3?C was seen in the phantom experiment, and a root mean square error (RMSE) outside the heated region of 2.3?Ccould be obtainedfor periodic motion. In the volunteer experiment, a RMSE of 2.7?C/2.9?C (triggered vs. breath hold) was measured. Conclusion A novel velocity navigator with Kalman filter postprocessing in real time significantly improves the temperature accuracy over non-triggered acquisitions and suggests being comparable to a breath-held acquisition. The proposed technique might be clinically applied for monitoring of thermal ablations in abdominal organs.
Original language | English (US) |
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Pages (from-to) | 15-22 |
Number of pages | 8 |
Journal | Magnetic Resonance Materials in Physics, Biology and Medicine |
Volume | 25 |
Issue number | 1 |
DOIs | |
State | Published - Feb 2012 |
Keywords
- Interventional MRI
- Kalman filter
- Motion compensation
- Thermometry
ASJC Scopus subject areas
- Biophysics
- Radiological and Ultrasound Technology
- Radiology Nuclear Medicine and imaging