Rapid fat/water assessment in knee bone marrow with inner‐volume rare spectroscopic imaging

An inner‐volume modification of a spectroscopic imaging technique based on RARE (rapid acquisition with relaxation enhancement) sequences is shown to provide, in less than 1 minute, spectra suitable for fat/ water peak‐area integration from selected imaging columns containing more than 1,000 5 × 5 × 1‐mm voxels. A limitation is the unavoidable T2 weighting of the spectral peaks, which influences estimations of true fat/ water composition from the spectra. Studies obtained in the knees of healthy volunteers demonstrate the ability of the technique to enable characterization of the two major proton peaks in bone marrow. Data collected at two or more effective TEs are suitable for extrapolation of fat/water estimates to zero TE.