Hexafluorobenzene: a Sensitive 19F NMR Indicator of Tumor Oxygenation

Abstract

We have surveyed the sensitivity of the spin lattice relaxation rates of the '% resonances of several perfluorocarbons to changes in oxygen tension and temperature. Hexafluorobenzene was found to exhibit exceptional sensitivity to changes in oxygen tension, and we have exploited this phenomenon to measure tumor oxygen tension following intratumoral injection. When 20 p1 hexafluorobenzene were injected they remained localized and the biodistribution was readily assessed on the basis of combined 'H and I9F three-dimensional MRI. Relaxation measurements indicated a typical baseline oxygen tension of 4.0k 1.5 torr in the central region of a Dunning prostate R3327-AT1 tumor when the rat breathed 66% oxygen. Altering the inspired oxygen concentration to 100% produced a modest increase in PO, (5.6k0.7 torr; peO.1). Significantly, the precision of these measurements should facilitate NMR investigations of radiobiological hypoxia. Intra-tumoral injection allowed measurements from regions not normally accessible to infused perfluorocarbons and provides an additional approach to measuring tumor oxygenation.

O2‐sensitive MRI distinguishes brain tumor versus radiation necrosis in murine models

“…1). Our findings are in accordance with previous MRI-based studies from other laboratories in which the paramagnetic nature of molecular oxygen was exploited to make MRI-based, quantitative inferences concerning tissue oxygenation (1)(2)(3)(4)(5)(6)(7)(8)(9)(10). From the linear relationship of pO 2 versus R 1 , we calculate the relaxivity of O 2 in brain tissue to be 9Â10 À4 6 3Â10 À4 mmHg À1 s À1 or, equivalently, 0.64 6 0.21 mM À1 s 1 .…”

Quantitative tissue oxygen measurement in multiple organs using 19F MRI in a rat model

“…Calibration Eq. 3 is similar to the calibration equation previously derived from 0 to 21% oxygen at 7T(22). The R 1 of HFB is highly sensitive to pO 2 but minimally sensitive to temperature.…”

Imaging tumor hypoxia by magnetic resonance methods

“…Adapted from refs. (74) and (76)) and reproduced with permission of the copyright owner. liver and spleen (average of 92 Torr) although, in the tumors, the increments were smaller (average of 32 Torr), but still statistically significant in both cases.…”