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The comparison was made to illustrate the factor, which leads to the difference of radiofrequency induced heating associated with implants between in-vivo and in-vitro. The simulations of virtual adult male and ASTM phantom, with a group of orthopedic plate implants, were performed in a body-sized birdcage coil driven at 128MHz. For femur and humerus orthopedic plate implants with various dimension,...
The objective of this study is to numerically compare the radio frequency (RF)-induced heating in transverse electromagnetic (TEM) coil and birdcage (BC) coil in the presence of circular leg fixator. We show that TEM coil generates a larger peak specific absorption rate averaged over 1 gram (SAR1g) than BC coil in the leg phantom with a generic circular external fixator. In the specific case, the...
Numerical studies of local specific absorption rate (SAR) were conducted for femoral plate implants in MRI 3T birdcage coil. Both the quadrature excitation and RF shimming conditions were evaluated in anatomical models of human body. All the results were normalized to 2W/kg average whole body SAR and Q-Matrices formalism method was used to improve the SAR calculation efficiency. The RF shimming procedure...
The objective of this study is to numerically compare the radio frequency (RF) — induced heating in transverse electromagnetic (TEM) coil and birdcage (BC) coil in the presence of circular leg fixator. We show that TEM coil generates a larger peak specific absorption rate averaged over 1 gram (SAR1g) than BC coil with circular external fixator. In the specific case, the peak SAR1g in TEM coil can...
In this study the helical stent is evaluated of the radio frequency (RF)-induced heating for the variation of gap and pitch under 1.5 T and 3 T magnetic resonance imaging (MRI). It is shown that the gap increment can reduce the peak 1 g averaged SAR and the pitch variation can also alter the heating. The detailed discussions are presented.
The comparison was made to illustrate the factor, which leads to the difference of radiofrequency induced heating associated with implants between in-vivo and in-vitro. The simulations of virtual adult male and ASTM phantom, with a group of orthopedic plate implants, were performed in a body-sized birdcage coil driven at 128MHz. For femur and humerus orthopedic plate implants with various dimension,...
Transfer function method was utilized to evaluate the RF-induced heating of implantable lead with 137 implanted lead trajectories under different shimming conditions. A coated wire is used to emulate medical leads. Two different shimming conditions were studied. One is to optimize the homogeneity of the B_(1+) field magnitude in human heart region, and second one is to estimate the possible worst-case...
In this study we present numerical simulations of the Specific Absorption Rate (SAR) for multi-component orthopaedic hip replacement systems. The SAR is used to evaluate the radio frequency (RF)-induced heating of the devices during magnetic resonance imaging (MRI). Because multi-component orthopaedic hip replacement systems have many combinations of components with various designs and sizes, it is...
The RF-induced heating is one of the main problems in diagnostic MRI. The standard way to assess the RF-induced heating is to perform experimental or computational phantom studies. Due to the inherent differences in geometry and electrical parameters between the phantom and the human body, the induced RF-induced heating assessed in the phantom is typically not be the same as in human body. In this...
One of the most critical MRI safety concerns for patients with medical implants is the RF coil induced heating in the vicinity of medical electrode lead tip. In this study, temperature rises for different lead path configurations are evaluated using transfer function method. Lead tip heating along three configurations: fully implanted, partially implanted, and minimum implanted medical electrode leads...
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