Bone marrow characterization in the lumbar spine with inner volume spectroscopic CPMG imaging studies

The authors describe new magnetic resonance (MR) spectroscopic and postprocessing methods for characterizing major proton peaks and their spectral T2 values in many small voxels throughout extensive regions of bone marrow within the adult lumbar spine. The techniques are based on spectroscopic interrogation of 128 voxels along columns oriented through the spine at eight TE values. Mean fat content measurements, based on quantification of the proton peaks of water and saturated fat (-CH₂-)_n, corrected for T2 decay, ranged from 40% to 60%. The mean T2 value of the lipid peak, 113 msec ±21, was significantly longer (P <.001) than that of water (71 msec ± 14). The techniques combine features of MR spectroscopy and imaging most suited for spatially efficient coverage of bone marrow at spectral resolutions sufficient for intravoxel fat or water content measurements. The methods introduced provide a practical, quantitative means for characterizing vertebral marrow in diseases affecting marrow cellularity.