title: Signal-to-noise ratio for hyperpolarized ³He MR imaging of human lungs: a 1.5 T and 3 T comparison.
abstract: The signal-to-noise ratio in hyperpolarized noble gas MR imaging is expected to be independent of field strength at frequencies typical of clinical systems (e.g., 1.5 T), where body noise dominates over coil noise. Furthermore, at higher fields (e.g., 3 T), the SNR of lung images may decline due to decreases in T(2) originating from increases in susceptibility-induced field gradients at the air-tissue interface. In this work, the SNR of hyperpolarized (3) He lung imaging at two commonly used clinical field strengths (1.5 T and 3 T) were compared in the same volunteers. Thermally polarized and hyperpolarized (3) He phantoms were used to account for differences in MR imaging system and (3) He polarizer performance, respectively, at the two field strengths. After correcting for T(2) values measured at 1.5 T (16 ± 2 ms) and 3 T (7 ± 1 ms), no significant difference in image SNR between the two field strengths was observed, consistent with theory.
authors.affiliation: Imaging Research, Sunnybrook Research Institute, Toronto, Ontario, Canada. wdguezv@sten.sunnybrook.utoronto.ca
authors.forename: William
authors.initials: W
authors.lastname: Dominguez-Viqueira
authors.forename: Alexei
authors.initials: A
authors.lastname: Ouriadov
authors.forename: Rafael
authors.initials: R
authors.lastname: O'Halloran
authors.forename: Sean B
authors.initials: SB
authors.lastname: Fain
authors.forename: Giles E
authors.initials: GE
authors.lastname: Santyr
mesh_terms: D000328:Adult; D006371:Helium; D006801:Humans; D008168:Lung / Q000033:anatomy & histology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D019047:Phantoms, Imaging; D059629:Signal-To-Noise Ratio
chemical_list: D006371:Helium