Temperature monitoring of ultrasonically heated muscle with RARE chemical shift imaging

The ability to monitor tissue temperature in ultrasonically heated rabbit muscle is demonstrated using a chemical shift imaging approach based on the rapid acquisition with relaxation enhancement (RARE) fast imaging method [Hennig et al., Magn. Reson. Med. 3, 823–833 (1986)] applied in a line scan f...

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Bibliographic Details
Published in:Medical physics (Lancaster) 1997-12, Vol.24 (12), p.1899-1906
Main Authors: Mulkern, Robert V., Chung, Andrew H., Jolesz, Ferenc A., Hynynen, Kullervo
Format: Article
Language:English
Subjects:
87.52
87.60.01
Animals
biomedical NMR
biomedical ultrasonics
Biothermics and thermal processes in biology
Body Temperature
chemical shift
Chemical shifts
Frequency measurement
Gels
hyperthermia
Hyperthermia, Induced
Image enhancement
Magnetic resonance imaging
Magnetic Resonance Imaging - methods
Medical imaging
muscle
Muscle, Skeletal - physiology
Muscles
patient monitoring
Phantoms, Imaging
Physicists
Rabbits
Silicones
Static and low‐frequency electric and magnetic fields effects
temperature measurement
Therapeutic applications
Ultrasonics
Ultrasonography
Water heating
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Summary:The ability to monitor tissue temperature in ultrasonically heated rabbit muscle is demonstrated using a chemical shift imaging approach based on the rapid acquisition with relaxation enhancement (RARE) fast imaging method [Hennig et al., Magn. Reson. Med. 3, 823–833 (1986)] applied in a line scan format. A three echo sequence with a 16 Hz spectral resolution with 64 ms echo readouts and 78 ms echo spacings is shown capable of measuring relevantly small water frequency shifts in phantoms. Applied to the in vivo model of ultrasonically heated rabbit muscle, water resonance frequencies at the ultrasonic focal point were found to be linearly related to temperature with a slope of −0.007 ± 0.001 ppm/°C ( N=6 studies). Measurements of the frequency shift in unheated tissue located away from the ultrasonically heated tissue varied by approximately 0.011 ppm over the course of the experiments, leading to an estimated temperature accuracy of ±1.6 °C in vivo.
ISSN:0094-2405
2473-4209
DOI:10.1118/1.598103