Study Of MRI Instruments Techniques

Magnetic Resonance Imaging (MRI) has become more and more important in clinical diagnostic and scientific researches. The Nobel Prize in Medicine (2003) was given to Paul C. Lauterbur and Peter Mansfield for their discoveries concerning magnetic resonance imaging. The key technique of MRI instruments is hold by several abroad companies, and this led to the high price of MR scanner. So the research of MRI instruments is necessary. The following content of this thesis is about an analog receiver for MR spectrometer based on PCI bus and wavelet based MR image denoising method.The first part introduce the basic principle of Magnetic Resonance Imaging and the structure of MRI spectrometer, which includes pulse sequence generator and compiler, RF unit,receiver unit and pulse field gradient unit. They're all based on PCI bus.The second part is mainly about the receiver which is the core component of MRI spectrometer. A low cost design of an analog receiver use one-chip receiver IF Subsystem is described. FPGA is used for logic controlling on the card. The hardware structure and the logic control flow of the receiver are described in detail. The MRI experiment result is also given.Finally, wavelet-based noise removal for MR imaging is discussed. We introduce the wavelet transform and its application in signal and image processing. Useful wavelet-based denoising methods are also introduced. Then we analyse the characteristic of noise in MRI. At last, two denoising methods based on wavelet for MR imaging are described in detail, with the result of its application in MR imaging.