Absolute thermometry using hyperpolarized 129 Xe free-induction decay and spin-echo chemical-shift imaging in rats.
Magn Reson Med
; 89(1): 54-63, 2023 01.
Article
em En
| MEDLINE
| ID: mdl-36121206
ABSTRACT
PURPOSE:
To implement and test variants of chemical shift imaging (CSI) acquiring both free induction decays (FIDs) showing all dissolved-phase compartments and spin echoes for specifically assessing 129 $$ {}^{129} $$ Xe in lipids in order to perform precise lipid-dissolved 129 $$ {}^{129} $$ Xe MR thermometry in a rat model of general hypothermia.METHODS:
Imaging was performed at 2.89 T. T 2 $$ {T}_2 $$ of 129 $$ {}^{129} $$ Xe in lipids was determined in one rat by fitting exponentials to decaying signals of global spin-echo spectra. Four rats (conventional CSI) and six rats (turbo spectroscopic imaging) were scanned at three time points with core body temperature 37/34/37 ∘ $$ {}^{\circ } $$ C. Lorentzian functions were fit to spectra from regions of interest to determine the water-referenced chemical shift of lipid-dissolved 129 $$ {}^{129} $$ Xe in the abdomen. Absolute 129 $$ {}^{129} $$ Xe-derived temperature was compared to values from a rectal probe.RESULTS:
Global T 2 $$ {T}_2 $$ of 129 $$ {}^{129} $$ Xe in lipids was determined as 251 . 3 ms ± 81 . 4 ms $$ 251.3\;\mathrm{ms}\pm 81.4\;\mathrm{ms} $$ . Friedman tests showed significant changes of chemical shift with time for both sequence variants and both FID and spin-echo acquisitions. Mean and SD of 129 $$ {}^{129} $$ Xe and rectal probe temperature differences were found to be - 0 . 1 5 ∘ C ± 0 . 9 3 ∘ C $$ -0.1{5}^{\circ}\mathrm{C}\pm 0.9{3}^{\circ}\mathrm{C} $$ (FID) and - 0 . 3 8 ∘ C ± 0 . 6 4 ∘ C $$ -0.3{8}^{\circ}\mathrm{C}\pm 0.6{4}^{\circ}\mathrm{C} $$ (spin echo) for conventional CSI as well as 0 . 0 3 ∘ C ± 0 . 7 7 ∘ C $$ 0.0{3}^{\circ}\mathrm{C}\pm 0.7{7}^{\circ}\mathrm{C} $$ (FID) and - 0 . 0 6 ∘ C ± 0 . 7 6 ∘ C $$ -0.0{6}^{\circ}\mathrm{C}\pm 0.7{6}^{\circ}\mathrm{C} $$ (spin echo) for turbo spectroscopic imaging.CONCLUSION:
129 $$ {}^{129} $$ Xe MRI using conventional CSI and turbo spectroscopic imaging of lipid-dissolved 129 $$ {}^{129} $$ Xe enables precise temperature measurements in the rat's abdomen using both FID and spin-echo acquisitions with acquisition of spin echoes enabling most precise temperature measurements.Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Imageamento por Ressonância Magnética
/
Termometria
Limite:
Animals
Idioma:
En
Revista:
Magn Reson Med
Assunto da revista:
DIAGNOSTICO POR IMAGEM
Ano de publicação:
2023
Tipo de documento:
Article
País de afiliação:
Alemanha