Influence of permittivity and electrical conductivity on image pattern of MRI

Takashi Harimoto, Seiichiro Ohno, Kengo Hattori, Miyuki Hirosue, Masahiro Miyai, Koichi Shibuya, Masahiro Kuroda, Susumu Kanazawa, Hirokazu Kato

Research output: Contribution to journalArticlepeer-review

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.

Original languageEnglish
Pages (from-to)147-159
Number of pages13
JournalJournal of X-Ray Science and Technology
Volume21
Issue number2
DOIs
Publication statusPublished - 2013

Keywords

  • MRI
  • RF magnetic field
  • conductivity
  • finite element method
  • flip angle
  • permittivity
  • signal intensity distribution

ASJC Scopus subject areas

  • Radiation
  • Instrumentation
  • Radiology Nuclear Medicine and imaging
  • Condensed Matter Physics
  • Electrical and Electronic Engineering

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