Monitoring of tumor reoxygenation following irradiation by 31P magnetic resonance spectroscopy: an experimental study of human melanoma xenografts.
OBJECTIVE
Inadequate tumor reoxygenation during radiation therapy may cause local treatment failure. This study was aimed at investigating the potential usefulness of 31P-MRS in monitoring tumor reoxygenation following radiation treatment.


METHODS
Tumors of two human melanoma xenograft lines (BEX-t and HUX-t) were exposed to 15.0 Gy, and then the fraction of radiobiologically hypoxic cells, measured by using the paired survival curve method, or tumor bioenergetic status, measured by 31P-MRS as the (PCr + NTPbeta)/Pi resonance ratio, was determined versus time after the radiation exposure.


RESULTS
Untreated BEX-t and HUX-t tumors showed similar fractions of radiobiologically hypoxic cells and similar bioenergetic status, whereas both parameters differed substantially between the lines in irradiated tumors. A close association was found between radiation-induced changes in tumor bioenergetic status and radiation-induced changes in the fraction of radiobiologically hypoxic cells.


CONCLUSIONS
31P-MRS is a potentially useful method for monitoring tumor reoxygenation following radiation treatment.
Olsen
D R
DR
Department of Medical Physics, The Norwegian Radium Hospital, Montebello, Oslo.
Rofstad
E K
EK
D000818:Animals; D016923:Cell Death; D015687:Cell Hypoxia / Q000528:radiation effects; D002470:Cell Survival / Q000528:radiation effects; D004734:Energy Metabolism / Q000528:radiation effects; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D018328:Melanoma, Amelanotic / Q000378:metabolism / Q000473:pathology / Q000532:radiotherapy*; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D008991:Monitoring, Physiologic; D009368:Neoplasm Transplantation; D010101:Oxygen Consumption / Q000528:radiation effects*; D010710:Phosphates / Q000378:metabolism; D010725:Phosphocreatine / Q000378:metabolism; D010759:Phosphorus Isotopes; D011879:Radiotherapy Dosage; D014183:Transplantation, Heterologous; D017211:Treatment Failure; D014407:Tumor Cells, Cultured
D010710:Phosphates; D010759:Phosphorus Isotopes; D010725:Phosphocreatine