Electrical and Electronics Commons^™

Characterization, Simulation, And Test Method For Image Artifacts Due To Phase Drift Of The Saw Filter In The Magnetic Resonance Receiver, Gabriel T. Jacobs

Theses and Dissertations

The receiver for a Magnetic Resonance (MR) scanner is responsible for capturing the precise frequency and phase of extremely low-power RF signals emanating from the human body; and consequentially must minimize unexpected phase drift in the received signal. One well-known source for temperature-dependent phase drift in RF electronics is the Surface Acoustic Wave (SAW) filter. In this work, the phase drift due to temperature changes in the SAW filter of an MR receiver was evaluated for its potential effects on image quality using several image quality metrics. A lab bench method was developed to playback MR images using typical lab-equipment …

Improving Mri Surface Coil Decoupling To Reduce B1 Distortion, Christian K. Larson

Theses and Dissertations

As clinical MRI systems continue to advance, larger focus is being given to image

uniformity. Good image uniformity begins with generating uniform magnetic fields, which

are easily distorted by induced currents on receive-only surface coils. It has become an

industry standard to combat these induced currents by placing RF blocking networks on

surface coils. This paper explores the effect of blocking network impedance of phased array surface coils on B1 distortion. It has been found and verified, that traditional approaches for blocking network design in complex phased arrays can leave undesirable B1 distortions at 3 Tesla. The traditional approach of …

Accelerating Mri Data Acquisition Using Parallel Imaging And Compressed Sensing, Haifeng Wang

Theses and Dissertations

Magnetic Resonance Imaging (MRI) scanners are one of important medical instruments, which can achieve more information of soft issues in human body than other medical instruments, such as Ultrasound, Computed Tomography (CT), Single Photon Emission Computed Tomography (SPECT), Positron Emission Tomography (PET), etc. But MRI's scanning is slow for patience of doctors and patients. In this dissertation, the author proposes some methods of parallel imaging and compressed sensing to accelerate MRI data acquisition. Firstly, a method is proposed to improve the conventional GRAPPA using cross-sampled auto-calibration data. This method use cross-sampled auto-calibration data instead of the conventional parallel-sampled auto-calibration data …