Techniques for improved time and data efficiency in Fourier-encoded magnetic resonance imaging

grantor: University of TorontoMagnetic resonance imaging is a diagnostic imaging modality in widespread clinical use around the world. White the value of this technology is proven, the availability of the procedure remains low. Part of the problem is due to the relatively long time required to complete a scan. Depending on the resolution and contrast required, MR image data can take up to several minutes to acquire. This thesis addresses the general problem of long scan times in clinical magnetic resonance imaging. The approach taken is to improve aspects of data collection efficiency. In the first part of the thesis, the conventional T2-weighted spin-echo imaging technique is considered. A method of increasing the number of anatomic section locations that may be acquired per unit time is described. The method may be used in conjunction with other methods for reducing scan time, such that the total amount of data collected remains the same. In the second part of the thesis, the technique of dynamic contrast-enhanced magnetic resonance imaging is considered. A strategy for trading spatial resolution to achieve the necessary temporal resolution for dynamic imaging with a spin-echo technique is described. The method is implemented for dynamic imaging of the pituitary gland and evaluated with a clinical study involving 18 patients. The method is further characterized in a retrospective analysis of dynamic contrast-enhanced breast images. In both parts of the thesis, modifications for reduced scan time are demonstrated in a manner which preserves the general image characteristics of the original pulse sequence methodology to which they are applied. Furthermore, the modifications may easily incorporated into clinical practice on standard magnetic resonance imaging hardware.Ph.D