Fig 3. Time course of citrate in DIBSG. A, Nonrandom residual signal, not accounted for by standard metabolites included in the LCModel basis set and consistent with citrate, can be detected in the MR spectrum obtained from a representative patient at the time of initial diagnosis. This signal is less readily detected in follow-up studies of this patient at 7 and 11 months when there was clinical progression of disease. Spectra are scaled to measured absolute concentrations to allow direct comparison of peak areas. Shown are unfiltered raw data (thin line) and the LCModel fit to the data (thick line). B, Plotted are tumor citrate concentrations versus time after initial diagnoses obtained from 6 patients in whom studies were performed repeatedly. Concentrations of citrate decrease significantly with time.