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J Magn Reson Imaging. 1998 Jan-Feb;8(1):175-81.

Calibration of water proton chemical shift with temperature for noninvasive temperature imaging during focused ultrasound surgery.

Author information

1
Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA. kagayaki@elec.eng.osaka-cu.ac.jp

Abstract

The present work was performed to calibrate water proton chemical shift change with tissue temperature in vivo to establish a method of quantitative temperature imaging during focused ultrasound surgery. The chemical shift change measured with a phase-mapping method using spoiled gradient-recalled acquisition in steady state (SPGR) (TR = 26 msec, TE = 12.8 msec, matrix = 256 x 128) was calibrated with the corresponding temperature elevation (0-50 degrees C, 32-84 degrees C in absolute temperature) measured with a copper-constantan thermocouple (.05-mm-diameter bare wires) in rabbit skeletal muscle (16 animals) under focused ultrasound exposures (10-100 W radiofrequency [RF] power, 20-second sonication). A linear calibration with a regression coefficient of (-8.76+/-.69) x 10(-3) ppm/degrees C (P < .01 [P, significance level]) was obtained. Temperature distributions during a 20-second sonication were visualized every 3.3 seconds with a 2.3-mm3 spatial resolution and 4 degrees C temperature uncertainty.

PMID:
9500277
DOI:
10.1002/jmri.1880080130
[Indexed for MEDLINE]

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