Evaluation of spatial resolution on fast spin-echo images. Effect of echo train length and interecho spacing

Fast spin echo (FSE) imaging technique has been indispensable in clinical MRI. This technique reduces acquisition time compared with conventional spin echo sequences. However, this technique introduces new factors, such as echo train length (ETL) and interecho spacing and is susceptible to a new set of artifacts, such as image blurring secondary to nonuniform sampling of K-space. Therefore, the effects of spatial resolution of FSE images on echo train length and interecho spacing were measured using the final MTF. FSE images of the chart phantom with some ETLs and bandwidth were exposed on laser films and measured by micro-densitometer in the phase-encoding direction. Using the final MTF method, the FSE images were evaluated for spatial resolution. Increasing ETL reduced spatial resolution on FSE images. The proton-density-weighted images were more conspicuous. Decreasing the bandwidth reduced spatial resolution on FSE images because of increasing interecho spacing. (author)