Metabolic Characterization of Human Soft Tissue Sarcomas in Vivo and in Vitro Using Proton-decoupled Phosphorus Magnetic Resonance Spectroscopy1

We applied 'H-decoupling and nuclear Overhauser enhancement to obtain well-resolved "I' magnetic resonance spectra accurately localized to 20 soft tissue sarcomas in vivo, using three-dimensional chemical shift imaging. Fifteen spectra had large phosphomonoester signals (21% of total phosphorus) that contained high amounts of phosphoethanolamine (compared to those of phosphocholine) but no signals from glycerophosphoethanolamine, and glycerophosphocholine was detected in only four cases. Prominent nucleoside triphosphates (52% of phosphorus) and low inorganic phosphate (10% of phosphorus) indicated that a large fraction of these 15 sarcomas contained viable cells, and this impression was confirmed histologically in 13 of the sarcomas. High-resolution in vitro "I' spectra of extracts of surgical specimens of four of the sarcomas studied in vivo and six additional sarcomas confirmed the in vivo assignments of metabolites and revealed considerable interand intratumoral variations of metabolite concentrations associated with histolÃ3gica) variations in the relative amounts of cells and of matrix materials or spontaneous necrosis. Seven sarcomas, all high grade with pleomorphic or round cells rather than spindle cells, contained an unidentified phosphodiester signal in vivn; its absence in the extract spectra indicates that it may be from an abnor mally mobile membrane component. We have documented a means to obtain new information about in vivo metabolism in human sarcomas and to provide a basis on which to examine the uses ol "I1 magnetic resonance spectroscopy in the clinical management of sarcomas.