Date of Award
Doctor of Philosophy
The quality of images produced by imaging devices of all types can be analyzed and quantified by a variety of metrics. Resolution is an important metric for all imaging devices because if the resolution characteristics do not meet the minimum requirements of an application, the resultant image may be unsuitable and possibly misleading. One resolution metric, called the Modulation Transfer Function (MTF), describes the ratio of input to output signal magnitude as a function of spatial frequency. Application of the MTF is limited to systems whose output scales linearly with input (linearity) and produces the same output image regardless of object position (shift invariance).;Although a variety of experimental MTF analysis techniques have been developed for a range of imaging devices, no suitable technique has been developed for a linear, shift invariant (within sub-regions) medical imaging modality called Magnetic Resonance Imaging (MRI). Magnetic Resonance Imaging is the three dimensional imaging modality of choice for detecting various soft tissue pathologies in the head, spinal cord and other anatomical regions of the human body. Unfortunately, most MR images are produced by the magnitude Fourier Transform (FT) reconstruction algorithm, a non-linear method which is not amenable to previously developed MTF analysis techniques. A new MTF analysis method, presented here, and developed specifically for MRI, eliminates the errors caused by the magnitude operator in the reconstruction algorithm by using the complex image formed just prior to the magnitude operator and modifying the MTF theory accordingly. Tests with experimentally produced MRI data have confirmed the feasibility of the new technique by producing accurate MTF's which agree with theoretically predicted resolution characteristics.
Steckner, Michael C., "Computing The Modulation Transfer Function Of Magnetic Resonance Imagers" (1994). Digitized Theses. 2349.