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Proton resonance frequency shift‐weighted imaging for monitoring MR‐guided high‐intensity focused ultrasound transmissions
Author(s) -
Chen JyunWen,
Huang TengYi,
Peng HsuHsia,
Chen WenShiang,
Tseng WenYih Isaac
Publication year - 2011
Publication title -
journal of magnetic resonance imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.563
H-Index - 160
eISSN - 1522-2586
pISSN - 1053-1807
DOI - 10.1002/jmri.22582
Subject(s) - contrast (vision) , ultrasound , magnitude (astronomy) , intensity (physics) , materials science , magnetic resonance imaging , phase (matter) , nuclear magnetic resonance , biomedical engineering , physics , optics , radiology , acoustics , medicine , quantum mechanics , astronomy
Purpose: To combine temperature‐related information of phase images and magnitude images acquired from an MR spoiled gradient echo sequence using a postprocessing method referred to as PRF‐shift‐weighted imaging (PRFSWI). Materials and Methods: Phase images are capable of detecting shifts in proton resonance frequency (PRF) caused by local changes in temperature. Magnitude images provide anatomical information for treatment planning and positioning as well as temperature‐related contrast. We used PRFSWI to produce a phase‐mask and performed multiplication on the magnitude image to increase temperature‐related contrast. Results: Through MRI‐guided focused ultrasound (MRIgFUS) experiments (both ex vivo and in vivo), we determined that PRFSWI is capable of enhancing the contrast of a heated area even in the initial stages of transmitting high‐intensity focused ultrasound energy. Conclusion: The PRFSWI images are sensitive to changes in temperature and display the heated spot directly in the magnitude images. Although the images do not provide quantitative data related to temperature, this method could be used as a complement to the phase temperature mapping method in the real‐time monitoring of MRIgFUS experiments. J. Magn. Reson. Imaging 2011;33:1474–1481. © 2011 Wiley‐Liss, Inc.