Study Of Self-Navigation Fast Spin Echo Technology At Low Field MR Scanner

Magnetic Resonance Imaging (MRI) has rapidly developed since early 80's of 20th century. Now it is widely used in medical diagnosis. Low-field open permanent MR scanners have become widely disseminated in many parts of the world, particularly the developing countries, as a means for low cost access to MRI technology for routine clinical examinations.Motion artifacts at low field MRI system are more severe than that at high field strength MRI due to longer scan time to improve the signal-noise-ratio. As a result, blurring and ghosting caused by patient motion may reduce anatomic detail and limit the detection of pathological findings. Multishot PROPELLER (periodically rotated overlapping parallel lines with enhanced reconstruction) approach, a self-navigation fast spin echo technique, is effective in suppression motion artifacts using segmental phase corrections and oversampling at the central k-space. Diffusion weighted imaging is an important technique for the assessment of acute ischemia. Single-shot echo planar imaging (EPI) , which is available at high field strength MRI systems with relatively strong and fast gradients, is the most common acquisition of choice for diffusion weighted imaging since it is very fast and minimizes any patient-related motion artifacts. However, EPI technology is not readily available on the lower-field open MRI systems.The main contents of this paper include:1. Implementation of self-navigation motion correction fast spin echo sequence at 0.35T open permanent MRI scanner.2. Study of image reconstruction method on self-navigation motion correction fast spin echo sequence.3. Study of diffusion weighted imaging combined with self-navigation motion correction fast spin echo sequence.