Document Detail


Velocity navigator for motion compensated thermometry.
MedLine Citation:
PMID:  21373916     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
OBJECT: Proton resonance frequency shift thermometry is sensitive to breathing motion that leads to incorrect phase differences. In this work, 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 ΔT = +37.3°C was seen in the phantom experiment, and a root mean square error (RMSE) outside the heated region of 2.3°C could 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.
Authors:
Florian Maier; Axel J Krafft; Joshua P Yung; R Jason Stafford; Andrew Elliott; Rüdiger Dillmann; Wolfhard Semmler; Michael Bock
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-3-4
Journal Detail:
Title:  Magma (New York, N.Y.)     Volume:  -     ISSN:  0968-5243     ISO Abbreviation:  -     Publication Date:  2011 Mar 
Date Detail:
Created Date:  2011-3-4     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9310752     Medline TA:  MAGMA     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
Medical Physics in Radiology (E020), German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120, Heidelberg, Germany, f.maier@dkfz.de.
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