SNAPSHOT ECHO-PLANAR IMAGING METHODS - CURRENT TRENDS AND FUTURE PERSPECTIVES

Ultra-high-speed imaging methods have gained in credibility over the past two years by virtue of improvements in imaging quality. This has come about by increases in both signal: noise ratios and image matrix size. Signal: noise improvements have been gained largely by use of higher magnetic field strengths. In echo-planar imaging (EPI) the image matrix size, and hence pixel resolution, depends on the use of large rapidly switched magnetic field gradients. Improvements in gradient coil design, the introduction of active magnetic screening of the coils and the availability of more powerful amplifiers, have all helped to achieve higher in-plane resolution. On our home-built system, operating at 0.5 T, the pixel resolution is currently 3 x 1.5 mm2 for a slice thickness of ca. 10 mm. The principles of EPI are briefly outlined and results of current techniques presented. Future perspectives will be directed to combinations of EPI with spectroscopy and new developments in echo-volumar imaging.