High speed direct digital acquisition system for magnetic resonance imaging.

摘要

The receiver of current Magnetic Resonance Imaging (MRI) systems employs analog processing circuitry in downconverting the MRI signal from the RF level to the baseband. Since digital circuits are not subject to the imprecision, noise, and temporal drift inherent in analog equipment, the use of digital technology can provide improvement in image quality. The theoretical aspects of a direct digital approach to the downconversion process are presented in the thesis; an actual implementation appears to be complex and, at higher sampling rates, possibly impractical. Therefore an alternative digital receiver of minimum complexity based on a simplified downconversion method has been proposed. Theoretical simulation of the method and images acquired with a developed prototype receiver constitute the proof of principle for the proposed alternative.