Michael Marx1, Kim Butts Pauly1. 1. Department of Radiology, Stanford University, Stanford, California, USA.
Abstract
PURPOSE: Low-bandwidth PRF shift thermometry is used to guide HIFU ablation treatments. Low sampling bandwidth is needed for high signal-to-noise ratio with short acquisition times, but can lead to off-resonance artifacts. In this work, improved multiple-echo thermometry is presented that allows for high bandwidth and reduced artifacts. It is also demonstrated with spiral sampling, to improve the trade-off between resolution, speed, and measurement precision. METHODS: Four multiple-echo thermometry sequences were tested in vivo, one using two-dimensional Fourier transform (2DFT) sampling and three using spirals. The spiral sequences were individually optimized for resolution, for speed, and for precision. Multifrequency reconstruction was used to correct for off-resonance spiral artifacts. Additionally, two different multiecho temperature reconstructions were compared. RESULTS: Weighted combination of per-echo phase differences gave significantly better precision than least squares off-resonance estimation. Multiple-echo 2DFT sequence obtained precision similar to single-echo 2DFT, while greatly increasing sampling bandwidth. The multiecho spiral acquisitions achieved 2× better resolution, 2.9× better uncertainty, or 3.4× faster acquisition time, without negatively impacting the other two design parameters as compared to single-echo 2DFT. CONCLUSION: Multiecho spiral thermometry greatly improves the capabilities of temperature monitoring, and could improve transcranial treatment monitoring capabilities. Magn Reson Med 76:747-756, 2016.
PURPOSE: Low-bandwidth PRF shift thermometry is used to guide HIFU ablation treatments. Low sampling bandwidth is needed for high signal-to-noise ratio with short acquisition times, but can lead to off-resonance artifacts. In this work, improved multiple-echo thermometry is presented that allows for high bandwidth and reduced artifacts. It is also demonstrated with spiral sampling, to improve the trade-off between resolution, speed, and measurement precision. METHODS: Four multiple-echo thermometry sequences were tested in vivo, one using two-dimensional Fourier transform (2DFT) sampling and three using spirals. The spiral sequences were individually optimized for resolution, for speed, and for precision. Multifrequency reconstruction was used to correct for off-resonance spiral artifacts. Additionally, two different multiecho temperature reconstructions were compared. RESULTS: Weighted combination of per-echo phase differences gave significantly better precision than least squares off-resonance estimation. Multiple-echo 2DFT sequence obtained precision similar to single-echo 2DFT, while greatly increasing sampling bandwidth. The multiecho spiral acquisitions achieved 2× better resolution, 2.9× better uncertainty, or 3.4× faster acquisition time, without negatively impacting the other two design parameters as compared to single-echo 2DFT. CONCLUSION: Multiecho spiral thermometry greatly improves the capabilities of temperature monitoring, and could improve transcranial treatment monitoring capabilities. Magn Reson Med 76:747-756, 2016.
Authors: W Jeffrey Elias; Diane Huss; Tiffini Voss; Johanna Loomba; Mohamad Khaled; Eyal Zadicario; Robert C Frysinger; Scott A Sperling; Scott Wylie; Stephen J Monteith; Jason Druzgal; Binit B Shah; Madaline Harrison; Max Wintermark Journal: N Engl J Med Date: 2013-08-15 Impact factor: 91.245
Authors: Mingming Wu; Hendrik T Mulder; Yuval Zur; Silke Lechner-Greite; Marion I Menzel; Margarethus M Paulides; Gerard C van Rhoon; Axel Haase Journal: MAGMA Date: 2018-12-04 Impact factor: 2.310