Conveners
Tue-Mo-Po2.06 - MRI Magnets II
- Lionel Quettier (CEA Paris-Saclay)
- Shoichi Yokoyama (Mitsubishi Electric Corporation)
Understanding the human brain in neuro scale is one of the main scientific challenges in the future. The sub-micron Magnetic Resonance Imaging (MRI) is significant to the structural and functional research of the human brain. The important way to improve the resolution of MRI scanner is increasing the magnetic field B_0, as it is well known that the signal to noise ratio (SNR) is proportional...
The Nb3Sn Rutherford cable and composite conductor is developed for 14T Magnetic Resonance Imaging (MRI) magnet project in China. Part of the project is devoted to the Electromagnetic (EM) behaviors studies of the deformed Nb3Sn strands from the cabling process. The magnetization characteristic of deformed Nb3Sn strands by artificial rolling method which simulates the transverse deformation is...
The objective of the magnet design for MRI is first to ensure the field intensity and homogeneity in the central imaging area, and meanwhile to minimize the magnetic leakage of the stray field. Based on this, an optimal design method of 14T actively shielded MRI magnets is proposed in this paper. Firstly the current carrying region of the magnets is subdivided into two-dimensional array grids,...
A 7 T superconducting magnet was designed and under fabrication for animal magnetic resonance imaging (MRI). The magnet includes two primary coils, four compensating coils and three shielding coils. All the coils together produced a homogeneous magnetic field over an imaging sphere with diameter 0.130 m and the stray field was actively-shielded within an area at longitudinal length 3 m and...
We present FEM results of a magnetic design study for 7 T, whole body, actively shielded MRI using Nb3Sn conductor. Nb3Sn strand was used to enable the development of short (1.4 m) segmented coil designs, as opposed to the nearly 2 m long compensated solenoid designs needed for NbTi machines. The use of Nb3Sn strand will allow a conduction cooled design, if quench is properly managed. We...
In superconducting magnetic resonance imaging (MRI) systems, time-varying eddy currents in the conducting cryostat structures are induced by switched gradient coils. These eddy currents increase thermal loads of the cryostat, create acoustic noise, lead to image distortion and limit the application of fast MR sequences. In this paper, a fast coupled circuit network method is employed to...
In magnetic resonance imaging (MRI) system, the magnetic field homogeneity of the imaging area plays a decisive role in the quality of images. Due to assembly errors or the effects of the surrounding ferromagnetic material, the homogeneity fails to meet the design value, which makes the images deformation, and it is necessary to take measures to shim. Passive shimming uses the magnetization of...
The Magnetic Resonance Imaging system（MRI）is an important diagnosis and treatment method of modern medicine. Benefiting from the advancement of superconducting magnet technology, the performance of MRI is continuously improved. In superconducting MRI, the main coils, as the most critical components, greatly determines the quality of images, further affecting the diagnosis. Therefore, the...
In ultra-high field magnetic resonance imaging (MRI) systems, the wavelength of the radiofrequency (RF) field is comparable to the size of imaging object, thus causing complicated coil-tissue interactions, which can lead to detrimental changes of the magnetic field (B1 field) and thermal intensity in human tissue. However, the homogeneity of B1 field and safety is critical for the RF coil,...
