Mitigation of artifacts in T1-weighted spiral projection imaging

Magnetic Resonance Imaging (MRI) is a proven method of obtaining high resolution, high contrast images of soft tissue. Among the various applications of MRI, T1-weighted contrast imaging is a staple in the diagnosis of many different diseases. Three-dimensional (3D) T1-weighted MRI provides additional information in many cases but also requires substantially longer scan times. This work introduces Spiral Projection Imaging (SPI) as a 3D TI-weighted MRI acquisition capable of providing high quality images in a reduced total scan time.The majority of MRI acquisition methods utilize a rectilinear sampling of k-space. Many alternative approaches have emerged over the history of MRI. One such approach samples k-space while spiraling outward from the origin and is known as spiral MRI. Spiral MRI serves as the basis of SPI. It provides greater sampling and signal-to-noise ratio (SNR) efficiency than the standard Cartesian acquisitions. Unfortunately, spiral MRI also suffers from many degradations introduced by off-resonant signal and gradient field distortions among other effects.Several approaches of mitigating the effects of gradient field errors and lipid off-resonant signal are presented. They are shown to substantially improve the quality of T1-weighted SPI data acquired in a spoiled gradient echo acquisition. The quality of SPI data is compared to the standard 3D Cartesian acquisition. The quality of SPI is found to be comparable to that of the Cartesian acquisition. However, the proposed reduction in scan time and improvement in SNR efficiency is not achieved in this work due to limitations imposed by off-resonance blurring.Rigid body motion of the patient's head is another source of artifact in T1-weighted imaging of the brain. It is shown that SPI can track rigid body patient motion directly from the acquired data. The SPI data can then be reconstructed in a manner that accounts for the motion and produces a substantial reduction in motion related artifact.