Soft-tissue sarcomas: MR imaging and MR spectroscopy for prognosis and therapy monitoring. Work in progress

The authors studied the usefulness of hydrogen-1 T2 measurements and phosphorus-31 magnetic resonance (MR) spectroscopy as indicators of prognosis and monitors of response to therapy in a group of patients with soft-tissue sarcomas. All eight patients were treated with combined local hyperthermia and fractionated radiation therapy, followed by surgical resection of the tumor. Each patient underwent T2 measurements and five patients underwent MR spectroscopy (phase encoded in one dimension) before treatment, after the first hyperthermia treatment, at the end of the therapy course, and just before surgery. Catheter thermometry was performed at each hyperthermia treatment. The T2 and MR spectroscopic variables were compared with thermometric data and the histologic findings from the complete surgical specimen. Changes in T2 correlated with histologic grade of tumor and thermometric data. The pretherapy tumor pH correlated positively, and changes during therapy in pH, ratio of phosphocreatine to inorganic phosphate (Pi), ratio of nucleoside triphosphate to Pi, and the phosphomonoester signal-to-noise ratio correlated negatively, with the percentage of tumor necrosis on the surgical specimen. These preliminary data suggest MR imaging and MR spectroscopy may be useful in the evaluation of such patients before and during therapy.