We studied the usefulness of P-31 MRS (magnetic resonance spectroscopy) for the early indication and monitoring of responses to radiation therapy in 30 patients with superficial tumors in the head and neck regions. P-31 MRS was used to estimate phosphomonoesters (PME) in tumors before and after patients were subjected to 20 Gy radiation therapy. Computed tomography ( CT) was carried out to measure tumor sizes before and after patients received 40~45 Gy of radiation. The relationship between the changes in PME levels and the reduction in tumor size was investigated.
In the tumors of 30 patients, the concentration ratio of PME / β -adenosine triphosphate
(ATP) was 0.99 ± 0.53 (mean±SD) before radiation treatment. The MR spectra of 23 tumors after 20 Gy radiation were detectable, but those of 7 tumors were not.
We found a significant positive correlation between the PME/ β-ATP reduction ratio and
the tumor reduction ratio for the 23 tumors with detectable spectra after being subjected to
20 Gy radiation. The response rate was 85.7% after 40~45 Gy radiation for the 7 tumors
with spectra below the noise level after 20 Gy radiation. The present results suggest that
PME/β-ATP is a useful parameter for estimation of the early response of tumors to radiotherapy.departmental bulletin pape
