Hypoxia imaging with the nitroimidazole 18F-FAZA PET tracer: a comparison with OxyLite, EPR oximetry and 19F-MRI relaxometry.
OBJECTIVE
(18)F-FAZA is a nitroimidazole PET tracer that can provide images of tumor hypoxia. However, it cannot provide absolute pO(2) values. To qualify (18)F-FAZA PET, we compared PET images to pO(2) measured by OxyLite, EPR oximetry and (19)F-MRI.


METHODS
Male WAG/Rij rats grafted with rhabdomyosarcoma were used. Tumor oxygenation was modified by gas breathing (air or carbogen). The same day of PET acquisition, the pO(2) was measured in the same tumor either by OxyLite probes (measurement at 10 different sites), EPR oximetry using low frequency EPR or (19)F-relaxometry using 15C5 on an 11.7T MR system.


RESULTS
There was a good correlation between the results obtained by PET and EPR (R = 0.93). In the case of OxyLite, although a weaker correlation was observed (R = 0.55), the trend for two values to agree was still related to the inverse function theoretically predicted. For the comparison of (18)F-FAZA PET and (19)F-MRI, no change in T(1) was observed.


CONCLUSIONS
A clear correlation between (18)F-FAZA PET image intensities and tumor oxygenation was demonstrated, suggesting that (18)F-FAZA PET is a promising imaging technique to guide cancer therapy.
Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium.
Ly-Binh-An
LB
Tran
Anne
A
Bol
Daniel
D
Labar
Bénédicte
B
Jordan
Julie
J
Magat
Lionel
L
Mignion
Vincent
V
Grégoire
Bernard
B
Gallez
D000818:Animals; D015687:Cell Hypoxia; D005462:Fluorine Radioisotopes; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D009374:Neoplasms, Experimental / Q000000981:diagnostic imaging; D009593:Nitroimidazoles; D010092:Oximetry / Q000379:methods*; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals; D051381:Rats; D012208:Rhabdomyosarcoma / Q000000981:diagnostic imaging
D005462:Fluorine Radioisotopes; D009593:Nitroimidazoles; D019275:Radiopharmaceuticals