Directions in magnetic resonance imaging technology.
Over the past few years there have been substantial improvements in the performance of magnetic resonance (MR) imagers. As image quality improved it became possible to perform studies in less time, increasing the throughput and the availability of the technique. A crucial contributor has been improvements in signal/noise. Techniques can now give signal/noise levels that a few years ago would have required much longer imaging times. With partial flip angle imaging techniques, it is possible to maintain image contrast and signal/noise while using reduced values of TR which decrease imaging time. It is also possible to decrease the number of acquired data lines and replace these lines mathematically at reconstruction time. Signal/noise is sacrificed, but the benefit is almost a factor of two in acquisition time. Echo planar techniques provide even higher speed imaging. In addition to the trade-off of signal/noise versus acquisition time, signal/noise can be traded for reduction in magnetic field strength. This results in reduced cost, improved patient access and also offers reduction in motion artifacts.
Ortendahl
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Radiologic Imaging Laboratory, University of California, San Francisco 94080.
Crooks
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D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods