Optimisation of 1H MRS quantitation with tissue water referencing in the presence of brain tumour heterogeneity

A tissue water signal is frequently used as a reference for metabolite quantitation by 1H MRS. We have determined the variability of T1, T2 and PD in glial brain tumours and normal brain to assess how tumour heterogeneity affects the reference signal at 3T. The typical short echo time MRS parameters TR 2000ms and TE 32ms reside within a “sweet spot” of minimum variation in the product PD*exp(-TE/T2)*1-exp(-TR/T1) that determines the water reference signal across a wide range of tissues (NWM, tumour core, necrosis and oedema). This choice also provides good SNR per unit time for the key metabolite singlets.