31P NMR spectroscopy can predict the optimum interval between fractionated irradiation doses.
This study was performed to clarify whether changes in the metabolites observed by phosphorous-31 magnetic resonance spectroscopy (31P-MRS) could indicate an optimum interval between two doses of radiation in a murine tumor model. Murine mammary carcinoma cells, FM3A, were irradiated 7 days after transplantation with a single 5 Gy dose without anesthesia. 31P spectra were measured with a spectrometer up to 30 days. The beta-ATP/Pi and PCr/Pi values were calculated from the peak area of each spectrum. In a fractionation experiment, two fractions of irradiation at a 5 Gy per fraction were given at 0, 1, 2, 3 and 6 day intervals. Tumor growth delay was also scored to determine the fractionated radiation effect. In the control group, beta-ATP/Pi and PCr/Pi decreased with tumor growth. In the single irradiation group, the tumor did not grow up to day 6, and an initial rise and subsequent decrease in beta-ATP/Pi and PCr/Pi were observed. Maximum beta-ATP/Pi and PCr/Pi were observed on day 2 after irradiation. In a fractionation experiment, the greatest growth delay was observed in the two day interval group, in which maximum beta-ATP/Pi and PCr/Pi were demonstrated in 31P-MRS. Our results suggested that changes in the metabolites observed by 31P-MRS could be useful indicators for determining the fractionation schedule in radiation therapy.
Murata
O
O
Department of Radiology and Radiation Oncology, Gunma University School of Medicine, Japan.
Sakurai
H
H
Mitsuhashi
N
N
Hasegawa
M
M
Yamakawa
M
M
Kurosaki
H
H
Hayakawa
K
K
Niibe
H
H
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D019583:Dose Fractionation, Radiation; D005260:Female; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008297:Male; D008325:Mammary Neoplasms, Experimental / Q000378:metabolism* / Q000473:pathology / Q000532:radiotherapy*; D051379:Mice; D008809:Mice, Inbred C3H; D010710:Phosphates / Q000378:metabolism; D010725:Phosphocreatine / Q000378:metabolism; D010758:Phosphorus; D013997:Time Factors; D014407:Tumor Cells, Cultured
D010710:Phosphates; D010725:Phosphocreatine; D010758:Phosphorus; D000255:Adenosine Triphosphate