Abstract 10743: Fluorine MR Angiography for Simultaneous Blood Flow and Oxygen Sensing with Circulating Perfluorocarbon (PFC) Nanoparticles (NP) at 4.7 T
Introduction: Traditional 1H cardiovascular MR angiography can define vascular structures with high resolution but measures of oxygenation remain a challenge. In this work, we demonstrate new imaging approaches employing intravascular PFC NP for both “no background” 19F angiography and for correlated non-invasive quantification of blood oxygen tension (PO2).
Methods: Swiss Webster mice were anesthetized with ketamine/xylazine followed by intravenous injection of 40% v/v perfluoro-15-crown-5-ether (CE) NP (5ml/kg). 30 mins post injection, 19F MRI and time-of-flight 1H MRI was acquired to visualize flow voids caused by carotid artery thrombosis induced by FeCl3. A novel blood enhanced saturation recovery (BESR) sequence was used to register 19F T1 in blood pool. The absolute PO2 in left ventricle (LV) and right ventricle (RV) were estimated from calibration data for PO2 vs. 19F T1.
Results: The in vitro calibration data revealed a linear relationship between 19F T1 and PO2 = (1/T1-0.366)/0.0023 mmHg across the range of values (0∼760 mmHg). Fig. A shows a “maximum intensity projection” of the 1H and 19F angiograms at the neck of mouse, where blood vessel geometry is clearly depicted. The thrombus site in the carotid artery is visually appreciable in 19F angiography (Fig. B), which is consistent with the time-of-flight 1H imaging (Fig. C). Fig. D&E illustrate the BESR sequence 19F MRI-determined ventricular PO2 map under normoxia and hyperoxia, respectively. The measured PO2 in left ventricle was 790 ± 113 mmHg on 100% O2 and 152 ± 122 mmHg on room air. The measured PO2 in right ventricle was 116 ± 43 mmHg under hyperoxia and 2 ± 66 mmHg under normoxia.
Conclusions: 19F angiography with PFC NP shows promise for providing both vasculature images and non-invasive measurement of blood oxygenation in deep tissues not amenable to conventional optical and chemical oximetry.
- © 2011 by American Heart Association, Inc.