Magnetic resonance elastography and diffusion-weighted imaging of the sol/gel phase transition in agarose. Sack, I., Gedat, E., Bernarding, J., Buntkowsky, G., & Braun, J.R. J Magn Reson, 166(2):252--261, Feb, 2004.
abstract   bibtex   
The dynamics of the sol/gel phase transition in agarose was analyzed with magnetic resonance elastography (MRE) and diffusion-weighted imaging, providing complementary information on a microstructural as well as on a macroscopic spatial scale. In thermal equilibrium, the diffusion coefficient of agarose is linearly correlated with temperature, independent of the sol/gel phase transition. In larger agarose samples, the transition from the sol to the gel state was characterized by a complex position and temperature dependency of both MRE shear wave patterns and apparent diffusion coefficients (ADC). The position dependency of the temperature was experimentally found to be qualitatively similar to the behavior of the ADC maps. The dynamics of the temperature could be described with a simplified model that described the heat exchange between sol and gel compartments. The experiments supported the approach to derive temperature maps from the ADC maps by a linear relationship. The spatially resolved dynamics of the temperature maps were therefore employed to determine the elasticities. For this reason, experimental MRE data were simulated using a model of coupled harmonic oscillators. The calculated images agreed well with the experimentally observed MRE wave patterns.
@article{ Sack2004a,
  author = {Sack, Ingolf and Gedat, Egbert and Bernarding, Johannes and Buntkowsky,
	Gerd and Braun, J�rgen},
  title = {Magnetic resonance elastography and diffusion-weighted imaging of
	the sol/gel phase transition in agarose.},
  journal = {J Magn Reson},
  year = {2004},
  volume = {166},
  pages = {252--261},
  number = {2},
  month = {Feb},
  abstract = {The dynamics of the sol/gel phase transition in agarose was analyzed
	with magnetic resonance elastography (MRE) and diffusion-weighted
	imaging, providing complementary information on a microstructural
	as well as on a macroscopic spatial scale. In thermal equilibrium,
	the diffusion coefficient of agarose is linearly correlated with
	temperature, independent of the sol/gel phase transition. In larger
	agarose samples, the transition from the sol to the gel state was
	characterized by a complex position and temperature dependency of
	both MRE shear wave patterns and apparent diffusion coefficients
	(ADC). The position dependency of the temperature was experimentally
	found to be qualitatively similar to the behavior of the ADC maps.
	The dynamics of the temperature could be described with a simplified
	model that described the heat exchange between sol and gel compartments.
	The experiments supported the approach to derive temperature maps
	from the ADC maps by a linear relationship. The spatially resolved
	dynamics of the temperature maps were therefore employed to determine
	the elasticities. For this reason, experimental MRE data were simulated
	using a model of coupled harmonic oscillators. The calculated images
	agreed well with the experimentally observed MRE wave patterns.},
  institution = {Department of Medical Informatics, Charit�-University Medicine Berlin,
	Campus Benjamin Franklin, Hindenburgdamm 30, D-12200 Berlin, Germany.},
  keywords = {Elasticity; Gels; Magnetic Resonance Imaging, methods; Phantoms, Imaging;
	Sepharose, chemistry; Temperature},
  language = {eng},
  medline-pst = {ppublish},
  owner = {Heiko},
  pii = {S1090780703003732},
  pmid = {14729037},
  timestamp = {2013.07.26}
}

Downloads: 0