Document Detail

Local hyperthermia with MR-guided focused ultrasound: spiral trajectory of the focal point optimized for temperature uniformity in the target region.
MedLine Citation:
PMID:  11042639     Owner:  NLM     Status:  MEDLINE    
The objective of hyperthermia treatment is to deliver a similar therapeutic thermal dose throughout the target volume within a minimum amount of time. We describe a noninvasive approach to this goal based on magnetic resonance imaging (MRI)-guided focused ultrasound (FUS) with a spherical transducer that can be moved along two directions inside the bed of a clinical MR imager and that has an adjustable focal length in the third dimension. Absorption of FUS gives rise to a highly localized thermal buildup, which then spreads by heat diffusion and blood perfusion. A uniform temperature within a large target volume can be obtained using a double spiral trajectory of the transducer focal point together with constant and maximum FUS power. Differences between the real and target temperatures during the first spiral are evaluated in real time with temperature MRI and corrected for during the second spiral trajectory employing FUS focal point velocity modulation. Once a uniform temperature distribution is reached within the entire volume, FUS heating is applied only at the region's boundaries to maintain the raised temperature levels. Heat conduction, together with the design and timing of the trajectories, therefore ensures a similar thermal dose for the entire target region. Good agreement is obtained between theory and experimental results in vitro on gel phantoms, ex vivo on meat samples, and in vivo on rabbit thigh muscle. Edema in muscle was visible 1 hour after hyperthermia as a spatially uniform rise of the signal intensity in T(2)-weighted images.
R Salomir; J Palussière; F C Vimeux; J A de Zwart; B Quesson; M Gauchet; P Lelong; J Pergrale; N Grenier; C T Moonen
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of magnetic resonance imaging : JMRI     Volume:  12     ISSN:  1053-1807     ISO Abbreviation:  J Magn Reson Imaging     Publication Date:  2000 Oct 
Date Detail:
Created Date:  2000-11-20     Completed Date:  2000-11-20     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  9105850     Medline TA:  J Magn Reson Imaging     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  571-83     Citation Subset:  IM    
Copyright Information:
Copyright 2000 Wiley-Liss, Inc.
Résonance Magnétique des Systèmes Biologiques, UMR 5536 CNRS/Victor Segalen, University Bordeaux 2, F-33076 Bordeaux, France.
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MeSH Terms
Hyperthermia, Induced / methods*
Magnetic Resonance Imaging / methods*
Muscle, Skeletal
Phantoms, Imaging
Ultrasonic Therapy* / methods

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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