THE RELATIONSHIP BETWEEN TUMOR 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 i n vivo, namely oxygen electrode measurement and magnetic resonance spe ctroscopy (MRS) of the fluorinated 2-nitroimidazole SR-4554, was inves tigated. Using three tumour models (two sites), no linear correlation was observed between F-19 retention index and pO(2), parameters (r les s than or equal to 0.3). Substantial retention of SR-4554 (F-19 retent ion 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), param eters used, SR-4554 administration was shown to produce either a signi ficant or a non-significant increase in tumour oxygenation. We conclud e that measurement of SR-4554-related compound(s) by F-19-MRS has the potential to detect clinically relevant levels of tumour hypoxia.