title: Calibration of water proton chemical shift with temperature for noninvasive temperature imaging during focused ultrasound surgery.
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.
authors.affiliation: Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA. kagayaki@elec.eng.osaka-cu.ac.jp
authors.forename: K
authors.initials: K
authors.lastname: Kuroda
authors.forename: A H
authors.initials: AH
authors.lastname: Chung
authors.forename: K
authors.initials: K
authors.lastname: Hynynen
authors.forename: F A
authors.initials: FA
authors.lastname: Jolesz
mesh_terms: D000818:Animals; D001834:Body Water; D002138:Calibration; D006614:Hindlimb; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy; D018482:Muscle, Skeletal / Q000473:pathology*; D011817:Rabbits; D015642:Radiology, Interventional; D014464:Ultrasonic Therapy