Assessment of the limiting spatial resolution of an MRI scanner by direct analysis of the edge spread function

Limiting spatial resolution is a key metric of the quality of magnetic resonance (MR) images, which can provide an indication of the smallest region that can effectively be imaged. In this paper a novel methodology for measuring the limiting spatial resolution of MR images is mathematically analyzed and successfully implemented on phantom images. The methodology presented in this paper is based on a direct fit of a mathematical expression of the edge spread function (ESF) profile to the ESF data acquired at the interface between different materials. The mathematical expression of ESF was determined by approximating the line spread function (LSF) of the system with a sinc function. The proposed methodology can be applied using signal data from magnitude MRI spin echo images and is not sensitive to noise amplification introduced by differentiating the ESF to produce the LSF, as performed in previous studies. In addition, the proposed methodology provides a quantitative, representative measurement of the limiting spatial resolution of MR images.