Three-dimensional magnetic resonance imaging of the pulmonary vascular system with rapid gradient echo acquisitions

by Wielopolski, Piotr Alfred

Abstract (Summary)
This dissertation demonstrates the utilization of 3-Dimensional Magnetic Resonance Imaging (MRI) incorporating magnetization prepared rapid gradient echo acquisition techniques in the study and assessment of the human pulmonary vascular system. The application of 3D techniques for the visualization of the pulmonary vascular tree is a major challenge for MRI. This is mostly due to the fact that the long data collection times involved in obtaining high resolution images leads to unavoidable image degradation, provided that thoracic motion is present. Despite this fact, the 3D approach allows for higher S/N, susceptibility artifact reduction with shorter echo times and isotropic data collection. The latter provides the benefit of multiplanar reconstructions (MPR) and a 3D visualization of the pulmonary To study the pulmonary vascular system, two approaches have been considered. First, a proton density/inflow weighted scan based a syncopated 3D FLASH acquisition is used to reconstruct a 3D angiogram of the pulmonary vascular tree. Secondly, a strong T1 weighted 3D IR-FLASH acquisition reduces the signal from blood and enhances tissues with shorter T1 values. The latter technique has demonstrated great potential and high sensitivity for the diagnosis of pulmonary emboli in patients with suspected pulmonary embolism, a disease that is estimated to be the third most common cause of death in the United States. The 3D IR-FLASH technique makes it possible to visualize bright emboli against a suppressed vascular tree. Furthermore, the 3D IR-FLASH scan helped explain the pitfalls of the syncopated 3D FLASH technique to demonstrate vessel occlusion as signal voids, initially thought to compare with the views generated in standard contrast angiograms, the gold standard for the detection of pulmonary embolism. aUsing these techniques, it has been possible to discriminate clot from blood and follow a patient through treatment to visualize improvements in pulmonary vascular flow. Multiple acquisitions and rectangular field-of-view are used to pseudogate to the respiratory period and reduce motion artifacts, while keeping reasonable imaging times. Technical aspects on data collection during the approach to equilibrium, acquisition strategies in the presence of thoracic motion and the impact on vessel resolution are addressed. (Abstract shortened by UMI.)
Bibliographical Information:


School:Case Western Reserve University

School Location:USA - Ohio

Source Type:Master's Thesis

Keywords:magnetic resonance imaging pulmonary vascular system


Date of Publication:01/01/1992

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