High-permittivity thin dielectric padding improves Fresh blood imaging of femoral arteries at 3 T

Marc D. Lindley*, Daniel Kim, Glen Morrell, Marta E. Heilbrun, Pippa Storey, Christopher J. Hanrahan, Vivian S. Lee

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

Objectives: Fresh blood imaging (FBI) is a useful noncontrast magnetic resonance angiographic (MRA) method for the assessment of peripheral arterial disease, particularly for imaging patients with poor renal function. Compared with 1.5 T, 3 T enables higher signal-to-noise ratio and/or spatiotemporal resolution in FBI. Indeed, previous studies have reported successful FBI of the calf station at 3 T. However, FBI of the thigh station at 3 T has been reported to suffer from signal void in the common femoral artery of 1 thigh only because of the radial symmetry in transmit radiofrequency field (B1+) variation. We sought to increase the signal of femoral artery in FBI at 3 T using high-permittivity dielectric padding. Materials and Methods: We performed FBI and B1+ mapping of the thigh station at 3 T in 13 human subjects to compare the following 3 dielectric padding settings: no padding, commercially available thick (approximately 5 cm) dielectric padding, and high-permittivity thin (approximately 2 cm) dielectric padding. We characterized the radial symmetry in B1+ variation as well as its impact on the FBI signal at baseline and how dielectric padding improves B1+ and FBI. We evaluated the quality of 3 FBI MRA acquisitions using quantitative (ie, contrast-to-noise ratio of femoral arteries) and qualitative (ie, conspicuity of femoral arteries) analyses. Results: With the subjects positioned on the magnetic resonance table in feetfirst, supine orientation, the radial symmetry in B1+ variation attenuates the signal in the right common femoral artery. The signal void can be improved partially with commercial padding and improved further with high-permittivity padding. Averaging the results over the 13 subjects, the mean B1+, contrast-to-noise ratio, and conspicuity scores for the right common femoral artery were significantly higher with high-permittivity padding than with commercial padding and baseline (P < 0.001). Conclusions: Our study shows that high-permittivity dielectric padding can be used to increase the signal of femoral artery in FBI at 3 T.

Original languageEnglish (US)
Pages (from-to)101-107
Number of pages7
JournalInvestigative radiology
Volume50
Issue number2
DOIs
StatePublished - Feb 1 2015

Keywords

  • B+ inhomogeneity
  • Dielectric padding
  • Fresh blood imaging
  • Noncontrast MRA
  • Peripheral arterial disease

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

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