Time-course of effects of external beam radiation on [18F]FDG uptake in healthy tissue and bone marrow.
The utility of PET for monitoring responses to radiation therapy have been complicated by metabolically active processes in surrounding normal tissues. We examined the time-course of [18F]FDG uptake in normal tissues using small animal-dedicated PET during the 2 month period following external beam radiation. Four mice received 12 Gy of external beam radiation, in a single fraction to the left half of the body. Small animal [18F]FDG-PET scans were acquired for each mouse at 0 (pre-radiation), 1, 2, 3, 4, 5, 8, 12, 19, 24, and 38 days following irradiation. [18F]FDG activity in various tissues was compared between irradiated and non-irradiated body halves before, and at each time point after irradiation. Radiation had a significant impact on [18F]FDG uptake in previously healthy tissues, and time-course of effects differed in different types of tissues. For example, liver tissue demonstrated increased uptake, particularly over days 3-12, with the mean left to right uptake ratio increasing 52% over mean baseline values (p < 0.0001). In contrast, femoral bone marrow uptake demonstrated decreased uptake, particularly over days 2-8, with the mean left to right uptake ratio decreasing 26% below mean baseline values (p = 0.0005). Significant effects were also seen in lung and brain tissue. Radiation had diverse effects on [18F]FDG uptake in previously healthy tissues. These kinds of data may help lay groundwork for a systematically acquired database of the time-course of effects of radiation on healthy tissues, useful for animal models of cancer therapy imminently, as well as interspecies extrapolations pertinent to clinical application eventually.
Kesner
Adam L
AL
Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, USA.
Lau
Victoria K
VK
Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, USA.
Speiser
Michael
M
Department of Radiation Oncology, David Geffen School of Medicine, University of California, Los Angeles, USA.
Hsueh
Wei-Ann
WA
Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, USA.
Agazaryan
Nzhde
N
Department of Radiation Oncology, David Geffen School of Medicine, University of California, Los Angeles, USA.
DeMarco
John J
JJ
Department of Radiation Oncology, David Geffen School of Medicine, University of California, Los Angeles, USA.
Czernin
Johannes
J
Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, USA.
Silverman
Daniel Hs
DH
Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, USA.
D000818:Animals; D001853:Bone Marrow / Q000000981:diagnostic imaging*; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics*; D008099:Liver / Q000000981:diagnostic imaging; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009928:Organ Specificity; D049268:Positron-Emission Tomography / Q000379:methods; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics*
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18