Natalie Schön1, Frank Seifert1, Gregory J. Metzger2, Bernd Ittermann1, and Sebastian Schmitter1,2
1Physikalisch-Technische Bundesanstalt (PTB), Braunschweig and Berlin, Germany, Berlin, Germany, 2Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, United States
1Physikalisch-Technische Bundesanstalt (PTB), Braunschweig and Berlin, Germany, Berlin, Germany, 2Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, United States
Electromagnetic simulations
demonstrate respiration-induced variations of the scattering matrix and its
dependence on breathing pattern, coil-body relationship, element type
(loop/dipole) and elements position.
Fig.2: Matrix variations of$$$\Delta S^{(motion)}$$$over
the respiratory cycle for 4 breathing pattern/coil setup combinations. The conventional breathing/fix coil setup shows strongest variation, due to largest
distance variations between coil and body. Posterior dipoles are more sensitive
on the respiratory motion than corresponding loops ($$$4^{th}$$$ and $$$5^{th}$$$: max loop: $$$1.04\cdot10^{-2}$$$, max dipole: $$$3.55\cdot10^{-2}$$$).
Fig.4: Schematic model
displacement curves over the respiratory cycle (a) for diaphragm and chest, and corresponding
$$$\Delta S_{ii}^{(motion)}$$$ for front elements i=L8/D8 (b) and posterior elements
i=L4/D4 (c). Strong variations are seen for front elements of conventional breathing/fix coil reflecting the impact of the coil-body distance. Coil
position/motion does not affect posterior elements, while the breathing type
(abdominal/chest) seems to have an impact.
