Rapid monitoring of oxygenation by ¹⁹F magnetic resonance imaging: Simultaneous comparison with fluorescence quenching

Abstract

The aim of this study was to develop an MRI fluorocarbon oximetry technique using snapshot inversion recovery and compare it with fluorescence quenching fiber-optic probe oximetry (OxyLite) performed simultaneously in experimental mouse tumors. The oxygen reporter probe hexafluorobenzene (HFB) was injected directly into the tumors, along with the insertion of the OxyLite probe. Tumor oxygenation (pO 2 ) was modified using carbogen or lethal doses of the anesthetic gas. MRI pO 2 maps were generated in 1.

Arsenic Trioxide Treatment Decreases the Oxygen Consumption Rate of Tumor Cells and Radiosensitizes Solid Tumors

“…For LLC tumors, the mean pO 2 after 45 minutes was 10.5 AE1.3 mm Hg for treated mice (n ¼ 5) and 4.3 AE 0.3 mm Hg for control mice (n ¼ 5; P < 0.01, t test). The effect of 5 mg/kg of As 2 O 3 on pO 2 was further confirmed by 19 F-MRI relaxometry in TLT tumors, which provides an estimation of the temporal and spatial heterogeneity of response. The mean tumor pO 2 was 15.9 AE 2.2 mm Hg before the injection of the drug and 30.8 AE 5.5 mm Hg 60 minutes after As 2 O 3 injection (time of maximal pO 2, according to this oximetry technique; P < 0.05, t test, n ¼ 5).…”

“…The first step of the study was to monitor pO 2 in experimental tumors using electron paramagnetic resonance (EPR) oximetry (18) after administration of As 2 O 3 to determine the window of increased tumor oxygenation. These results were confirmed by 19 fluorine MRI ( 19 F-MRI) oxygen mapping, a technique that can probe the spatial heterogeneity of response (19,20). Patent blue staining (blood flow) and in vitro oxygen consumption experiments were done to investigate the origin of the observed increase in pO 2 .…”

“…The mean tumor pO 2 was 15.9 AE 2.2 mm Hg before the injection of the drug and 30.8 AE 5.5 mm Hg 60 minutes after As 2 O 3 injection (time of maximal pO 2, according to this oximetry technique; P < 0.05, t test, n ¼ 5). The evolution of pO 2 over time, as measured by 19 F-MRI relaxometry, is shown in Fig. 2.…”

“…MRI was done with a 4.7 T, 40-cm inner diameter bore system (Bruker Biospec) and a tunable 1 H/ 19 F surface coil. Parametric images of the spinlattice relaxation time (T 1 ) were estimated using a snapshot inversion recovery (SNAP-IR) pulse sequence, using a protocol described previously (19). Hexafluorobenzene (HFB) was slowly injected into the tumor and deposited along 3 tracks (3 Â 30 mL) encompassing central and peripheral regions.…”

Monitoring of hemodynamic changes induced in the healthy breast through inspired gas stimuli with MR-guided diffuse optical imaging

“…4 To compensate for the loss in vascular tone during oxygen breathing, carbogen gas, which contains a large percentage of O 2 mixed with a small concentration of CO 2 ͑usually 1%-5%͒, can be used to limit vascular constriction. 12,9 Carbogen has been shown to increase both tissue blood flow 8,13 and tissue oxygenation [14][15][16] compared to oxygen breathing. Increased tissue pO 2 due to carbogen has been reported in the cerebrum, 13 liver, spleen, paraspinal muscle, and subcutaneous fat.…”