Velocity navigator for motion compensated thermometry
- نوع فایل : کتاب
- زبان : انگلیسی
- مؤلف : Florian Maier · Axel J. Krafft · Joshua P. Yung · R. Jason Stafford · Andrew Elliott · Rüdiger Dillmann · Wolfhard Semmler · Michael Bock
- چاپ و سال / کشور: 2011
Description
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 obtained for 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.
Magn Reson Mater Phy DOI 10.1007/s10334-011-0245-z Received: 2 December 2010 / Revised: 7 February 2011 / Accepted: 7 February 2011
