[Use of fluorine-19 nuclear resonance spectroscopy for the measurement of changes induced in blood perfusion volume in experimental tumors in vivo].

The biological response of some anti-cancer therapeutic agents is probably mediated via the tumour vasculature. A novel approach using 19F NMR spectroscopy in vivo has been developed to directly measure changes in vascular perfusion volume in experimental tumours. A 100% w/v perfluorooctylebromide (PFOB) emulsion was used as a tracer. For a fixed position of a 7 mm surface coil placed over the tumour, the signal from the PFOB rapidly reached an equilibrium value remaining unchanged for at least 2 hours. Since the strength of the fluorine signal is directly proportional to the perfusion volume of the tumour vasculature, reduction of signal intensity should correspond directly to any reduction in volume which may be a manifestation of a change in the tumour blood flow. This hypothesis was investigated using hydralazine as a physiological modifier of tumour blood flow. Administration of 5 mg/kg of hydralazine following dosing with the PFOB emulsion reduced the 19F signal intensity from the murine tumors RIF-1 and KHT and from the human tumour HT29 with no or little reduction in the SCCVII/Ha murine and HX118 human tumours. Changes in blood volume in KHT tumour accompanied local changes in tumour blood flow rate as measured by the Xe-133 clearance rate technique. Thus, these data demonstrate the potential of the PFOB emulsion as a 19F NMR tracer of the vasculature to measure changes induced by therapeutic agents on blood volume in accessible tumours. This method may also be useful to detect early changes in blood volume produced during angiogenesis of solid tumours or angiostatic activity of anti-cancer drugs.