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Temperature measurement using echo-shifted FLASH at low field for interventional MRI.
- Source :
-
Journal of magnetic resonance imaging : JMRI [J Magn Reson Imaging] 1999 Jan; Vol. 9 (1), pp. 138-45. - Publication Year :
- 1999
-
Abstract
- We investigated the feasibility of using echo-shifted fast low-angle shot (FLASH) for temperature-monitored thermo-therapeutic procedures in a 0.2 T interventional magnetic resonance (MR) scanner. Based on the proton resonance frequency shift technique, modified echo-shifted FLASH has sufficiently high signal-to-noise ratio to provide accurate temperature maps with short scan times, i.e., 5 seconds in phantoms (TR = 20.5 msec; effective TE = 30 msec; one echo shift; NSA = 2) and ex vivo experiments (TR = 19.4 msec; effective TE = 28.9 msec; one echo shift; NSA = 2) and 3 seconds (TR = 19.4 msec; effective TE = 28.9 msec, one echo shift; NSA 1) for an in vivo case. The proton resonance frequency shifts with temperature observed in a 0.2 T MR scanner using this sequence were -0.0072 ppm/degrees C (temperature uncertainty = +/-2.5 degrees C) for polyacrylamide phantoins and -0.0086 ppm/degrees C (temperature uncertainty = +/- 1 degrees C) for ex vivo bovine liver. These experiments demonstrated that echo-shifted FLASH is a viable method for low-field temperature monitoring despite the decreased signal and decreased phase sensitivity compared with its counterpart in a 1.5 T MR imaging system. The improved temporal resolution of temperature images, now possible in low-field interventional MR systems using echo-shifted FLASH, will allow clinicians more accurate monitoring of interstitial ablation in MR-guided interventional procedures.
Details
- Language :
- English
- ISSN :
- 1053-1807
- Volume :
- 9
- Issue :
- 1
- Database :
- MEDLINE
- Journal :
- Journal of magnetic resonance imaging : JMRI
- Publication Type :
- Academic Journal
- Accession number :
- 10030661
- Full Text :
- https://doi.org/10.1002/(sici)1522-2586(199901)9:1<138::aid-jmri18>3.0.co;2-a