Chemical-shift-selective magnetic-resonance imaging of avascular necrosis of the femoral head.

Chemical-shift-selective (CHESS) nuclear-magnetic-resonance (NMR) imaging is a new method for separating "water" and "fat" (CH2) resonances in proton NMR imaging. Its major advantage over conventional composite NMR imaging is the contrast enhancement, which in particular allows the detection of small water-containing structures, such as vessels or joint surfaces, normally obscured by fat signals. First clinical findings in the femoral head with avascular necrosis are reported.