Camille D.E. Van Speybroeck1, Wouter M. Teeuwisse1, Tom O'Reilly1, Paul M. Arnold2, and Andrew G. Webb1
1G.J. Gorter Center for High Field MRI, Leiden University Medical Center, Leiden, Netherlands, 2Neurosurgery, Carle Foundation Hospital, Urbana, IL, United States
1G.J. Gorter Center for High Field MRI, Leiden University Medical Center, Leiden, Netherlands, 2Neurosurgery, Carle Foundation Hospital, Urbana, IL, United States
On very low
field MRI systems image artifacts are significantly reduced compared to 3T
despite much weaker gradients, SAR limits can potentially be reached using
short RF pulses and inter-echo TSE times, and some medical implants are MR
unsafe.
Figure 2 Susceptibility artifacts from the
septal occluder, the stent and the endoscopic clip. A bandwidth of 156Hz/pixel
is used on the 50 mT system (top row), which is matched by the first 3 T scan
(middle row), whilst the bottom row shows the 3 T images acquired with 880Hz/pixel.
In the images the direction of the main magnetic field (B0) and the
frequency- and the two phase-encoding directions are indicated.
Figure 1 (a)
The setup for the magnetically induced displacement force measurement inside
the 50 mT system with the angle of deflection α’, angle of rotation β and absolute angle of deflection α indicated. It is based on the F2052-15 ASTM
protocol4 with the additional capability of rotating the device to enable
measurement of the variation along the z-axis. (b) The central xz-plane of the
simulation data for the scalar gradient of the magnetic field, with the measurable
area (red) indicated.