The relationship between tumour oxygenation determined by oxygen electrode measurements and magnetic resonance spectroscopy of the fluorinated 2-nitroimidazole SR-4554

The relationship between two methods of assessing tumour oxygenation in vivo, namely oxygen electrode measurement and magnetic resonance spectroscopy (MRS) of the fluorinated 2-nitroimidazole SR-4554, was investigated. Using three tumour models (two sites), no linear correlation was observed between F-19 retention index and pO(2), parameters (r less than or equal to 0.3). Substantial retention of SR-4554 (F-19 retention index > 0.5) was, however, associated with low tumour pO(2), (% pO(2),less than or equal to 5 mmHg = 60%). Depending on the pO(2), parameters used, SR-4554 administration was shown to produce either a significant or a non-significant increase in tumour oxygenation. We conclude that measurement of SR-4554-related compound(s) by F-19-MRS has the potential to detect clinically relevant levels of tumour hypoxia.