title: Influence of permittivity and electrical conductivity on image pattern of MRI.
abstract: In proton density-weighted (PDW) MR imaging, the patterns of signal intensity vary depending on the imaged material, and change with the flip angle (FA) applied to the imaged material. The correlation between the pre-determined FA and the actual FA applied to imaged objects was investigated using 4 types of phantoms having different dielectric properties. PDW images were acquired using the spin-echo (SE) method and different pre-determined FA. Dependency of the signal intensity distribution in the phantom on the pre-determined FA differed among phantoms: patterns for water and 0.402 w/w% saline solution phantoms changed with the pre-determined FA, whereas those for olive oil and 4.02 w/w% saline solution phantoms were barely affected by the pre-determined FA. Causes of these phenomena were considered to be the differences between the pre-determined FA and the actual FA among the phantoms; differences were also influenced by the positioning of the phantom. Our study showed that the actual FA in the phantom is greater than the pre-determined FA in high permittivity media, whereas it is reduced by an increased conductivity of the media.
authors.affiliation: Graduate School of Health Sciences, Okayama University, Shikata-cho, Okayama, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Harimoto
authors.forename: Seiichiro
authors.initials: S
authors.lastname: Ohno
authors.forename: Kengo
authors.initials: K
authors.lastname: Hattori
authors.forename: Miyuki
authors.initials: M
authors.lastname: Hirosue
authors.forename: Masahiro
authors.initials: M
authors.lastname: Miyai
authors.forename: Koichi
authors.initials: K
authors.lastname: Shibuya
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kuroda
authors.forename: Susumu
authors.initials: S
authors.lastname: Kanazawa
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Kato
mesh_terms: D004553:Electric Conductivity; D004574:Electromagnetic Fields; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008962:Models, Theoretical; D019047:Phantoms, Imaging; D012815:Signal Processing, Computer-Assisted