Proton (fat/water) chemical shift imaging in medical magnetic resonance imaging. Current status.
Fat/water CSI has recently been transformed from an experimental method to a routine clinical MRI approach, particularly for evaluating paramagnetic contrast enhancement in fat-rich regions and as a piggyback method for decreasing MRI artifacts, such as in MR angiographic and echo-planar imaging. The full and appropriate use of CSI in medical MRI requires consideration of the factors and strategies outlined in this review. As the commercial implementation of fat/water CSI continues, we can expect further applications in clinical and experimental studies. For example, in imaging areas where MRI has been of limited efficacy, such as pancreas imaging, skin microimaging and vascular imaging, there are indications that these CSI methods may have practical importance. It seems reasonable to project that for high chemically specific detail, medical fat/water CSI will ultimately be supplanted by SI methods, and certainly by localized spectroscopy. The power of the fat/water CSI method remains its extremely high anatomic resolution, which cannot be achieved by current spectroscopy or SI methods. The fat/water CSI methods provide a means for clinically relevant MRI with more accurate and chemically specific information. Expansion of these methods into three-dimensional and fast imaging formats is already taking place at or near the commercial level. For example, the feasibility of combining echo-planar imaging and CSI methods has already been demonstrated. Methods based on the phase-contrast techniques, such as susceptibility mapping and interferometry, are additional implementations that can provide detailed and more specific information in a high anatomic detail format.