In Vivo Mapping of Deep Tissue pO ₂ in a Murine Model of Peripheral Artery Disease by Noninvasive ¹⁹ F MR Relaxometry

HomeArteriosclerosis, Thrombosis, and Vascular BiologyVol. 43, No. 4In Vivo Mapping of Deep Tissue pO2 in a Murine Model of Peripheral Artery Disease by Noninvasive 19F MR Relaxometry Free AccessLetterPDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessLetterPDF/EPUBIn Vivo Mapping of Deep Tissue pO2 in a Murine Model of Peripheral Artery Disease by Noninvasive 19F MR Relaxometry Nicolas Stumpe, Tuba Güden-Silber, Rebekka Schneckmann, Katharina Wolters, Hildo Lamb, Maria Grandoch and Ulrich Flögel Nicolas StumpeNicolas Stumpe https://orcid.org/0000-0002-8708-7844 Institute for Molecular Cardiology, Heinrich Heine University, Düsseldorf, Germany (N.S., T.G.-S., U.F.). Cardiovascular Imaging, University Medical Center, Leiden, the Netherlands (N.S., H.L.). *N. Stumpe and T. Güden-Silber contributed equally. Search for more papers by this author , Tuba Güden-SilberTuba Güden-Silber https://orcid.org/0000-0002-2668-9542 Institute for Molecular Cardiology, Heinrich Heine University, Düsseldorf, Germany (N.S., T.G.-S., U.F.). *N. Stumpe and T. Güden-Silber contributed equally. Search for more papers by this author , Rebekka SchneckmannRebekka Schneckmann https://orcid.org/0000-0001-8692-309X Institute for Translational Pharmacology, Heinrich Heine University, Düsseldorf, Germany (R.S., K.W., M.G.). Search for more papers by this author , Katharina WoltersKatharina Wolters Institute for Translational Pharmacology, Heinrich Heine University, Düsseldorf, Germany (R.S., K.W., M.G.). Search for more papers by this author , Hildo LambHildo Lamb https://orcid.org/0000-0002-6969-2418 Cardiovascular Imaging, University Medical Center, Leiden, the Netherlands (N.S., H.L.). Search for more papers by this author , Maria GrandochMaria Grandoch https://orcid.org/0000-0002-4382-1947 Institute for Translational Pharmacology, Heinrich Heine University, Düsseldorf, Germany (R.S., K.W., M.G.). Search for more papers by this author and Ulrich FlögelUlrich Flögel Correspondence to: Ulrich Flögel, PhD, Institute for Molecular Cardiology, Heinrich Heine University, Universitätsstraße 1, 40225 Düsseldorf, Germany. Email E-mail Address: [email protected] https://orcid.org/0000-0001-7181-4392 Institute for Molecular Cardiology, Heinrich Heine University, Düsseldorf, Germany (N.S., T.G.-S., U.F.). Search for more papers by this author Originally published9 Feb 2023https://doi.org/10.1161/ATVBAHA.122.318548Arteriosclerosis, Thrombosis, and Vascular Biology. 2023;43:597–598Other version(s) of this articleYou are viewing the most recent version of this article. Previous versions: February 9, 2023: Ahead of Print Peripheral arterial disease is characterized by varying degrees of hypoxia due to chronic progredient occlusion of peripheral arteries. Here, we report an in vivo approach for direct determination of tissue pO2 in peripheral arterial disease with background-free, noninvasive fluorine magnetic resonance imaging (19F MRI) using physiologically inert perfluorocarbon nanoemulsions.Perfluorocarbon nanoemulsions dissolve paramagnetic oxygen proportional to the ambient pO2, resulting a linear increase in the 19F relaxation rate R1 (R1=1/T1).1 However, for pO2 calculation, the temperature dependence of 19F T1 relaxation has to be considered and a fast, artifact-free magnetic resonance imaging acquisition technique is required. For this, FAIR-EPI (flow-sensitive alternating inversion-recovery echo planar imaging sequence) was used at 9.4T (Bruker AVANCENEO) with a 25-mm resonator tunable to both 1H (linear) and 19F (quadrature). Rescaling of the trajectories acquired in reference 1H flow-sensitive alternating inversion-recovery echo planar imaging sequence scans allowed the elimination of ghosting artifacts along the phase encoding direction for the corresponding 19F measurements (Figure [A]). Calibration curves were recorded within 31 °C to 39 °C using a 20% perfluoro-15-crown-5 ether nanoemulsion2 utilizing the setup in Figure [B]. As expected, we found a temperature-dependent linear relationship between 19F relaxation rate R1 and pO2 (Figure [C]).Download figureDownload PowerPointFigure. 19F MRI relaxometry reveals gradual tissue pO2 profiles in murine hindlimb ischemia (HLI). A, For in vivo validation of the pulse sequence, PFCs were injected into the right murine hindlimb (yellow arrow). First: 1H anatomical reference (RARE), Second: FAIR-EPI (flow-sensitive alternating inversion-recovery echo planar imaging sequence) 19F image with ghosting artefacts (asterisks), Third: artifact-free FAIR EPI 19F image with adjusted trajectories, Fourth: merge of 19F (hot iron) and 1H greyscale images. 19F FAIR-EPI: TE: 8.72 ms, TR: 5000 ms, ST: 2 mm, matrix: 64×64, FOV: 40×40 mm2, 48, TI: 25/400/800/1200/1600 ms; TAcq: 20 minutes). B, Calibration setup for pO2 determination parallel to acquisition of T1 maps, starting at ambient pO2 and gradually displacing oxygen by step-wise flushing with nitrogen. pO2 was continuously monitored with a fiber optic pO2 probe. C, Fitted surface from the calibration curves acquired at 31/33/35/37/39 °C (n=3). D, Scheme of the HLI model (zoom-in left) and slice localization (red, middle) to acquire spatially resolved pO2 maps for upper/lower limbs (right). E, Left: pO2 for sham vs HLI for thigh/calf. pO2 was calculated from measured 19F R1 with the formula in C using 34.6/33.8 °C for thigh/calf as obtained from invasive measurements. Right: pO2 in ischemic thigh/calf for those animals receiving PFC injections in both regions. A Student t-test was utilized to determine statistically significance (P value <0.05).Reference values were determined within thigh/calf of anesthetized mice by invasive sensors (NTH-PSt7/OXY-4; MIT-18/testo-108), yielding pO2 of 26.2±2.0 mmHg (n=5) and temperatures of 34.6±0.4/33.8±0.2 °C for thigh/calf (n=5), the latter were used for conversion of in vivo 19F R1 to corresponding pO2 using the formula in Figure [C].Thereafter, 19F MRI was applied to assess tissue pO2 in a murine hindlimb ischemia model (HLI; see Figure [D], left; male 16–18 weeks C57BL/6J mice as approved by local authorities [LANUV]).3 For determination of tissue pO2, directly after surgery, 100 µL perfluorocarbon nanoemulsions were injected into the muscle of both upper hindlimbs (n=9) just below the first site of ligation and in a subset of n=3 animals also 50 µL perfluorocarbon nanoemulsions into both calf muscles (Figure [D], arrows). After 24 hours, 19F T1 was determined to quantify pO2 in both hindlimbs. While pO2 in sham thighs was found to be 28.8±6.8 mmHg (the same range as reference values above), pO2 in ischemic legs was significantly decreased to 11.6±4.6 mmHg (Figure [D] and [E], n=9 each; P=2.2×10−5) as validated by invasive measurements (13.8±4.8 mmHg at unchanged temperatures of 34.6±0.3 °C). The calf revealed similar pO2 at the control site, but an even larger pO2 drop in HLI (31.2±6.4 versus 4.2±3.3 mmHg, n=3 each; P=0.006).Taken together, 19F MRI (1) resulted in similar pO2 values as invasive measures and allowed (2) the assessment of the degree of tissue hypoxia as well as (3) mapping of the gradual pO2 profile toward the periphery associated with the utilized peripheral arterial disease model. Beyond current perfusion/optical techniques or superficial O2 measurements, our approach allows assessment of deep tissue pO2, providing a meaningful measure of the consequences of impaired perfusion that reflects the true mismatch between demand and supply of the affected tissue. With this, our technology implies a substantial translational potential for early diagnosis of limited tissue supply.Article InformationSources of FundingThis work was supported by the DFG (INST 208/764-1 FUGG) and the EC (MSCA-ITN-2019 “NOVA-MRI”).Disclosures None.Footnotes*N. Stumpe and T. Güden-Silber contributed equally.For Sources of Funding and Disclosures, see page 598.Correspondence to: Ulrich Flögel, PhD, Institute for Molecular Cardiology, Heinrich Heine University, Universitätsstraße 1, 40225 Düsseldorf, Germany. Email floegel@uni-duesseldorf.deReferences1. Thomas SR, Pratt RG, Millard RW, Samaratunga RC, Shiferaw Y, Clark LC, Hoffmann RE. Evaluation of the influence of the aqueous phase bioconstituent environment on the F-19 T1 of perfluorocarbon blood substitute emulsions.J Magn Reson Imaging. 1994; 4:631–635. doi: 10.1002/jmri.1880040421CrossrefMedlineGoogle Scholar2. Flögel U, Ding Z, Hardung H, Jander S, Reichmann G, Jacoby C, Schubert R, Schrader J. In vivo monitoring of inflammation after cardiac and cerebral ischemia by fluorine magnetic resonance imaging.Circulation. 2008; 118:140–148. doi: 10.1161/CIRCULATIONAHA.107.737890LinkGoogle Scholar3. Schneckmann R, Suvorava T, Hundhausen C, Schuler D, Lorenz C, Freudenberger T, Kelm M, Fischer JW, Flögel U, Grandoch M. Endothelial hyaluronan synthase 3 augments postischemic arteriogenesis through CD44/eNOS signaling.Arterioscler Thromb Vasc Biol. 2021; 41:2551–2562. doi: 10.1161/ATVBAHA.121.315478LinkGoogle Scholar Previous Back to top Next FiguresReferencesRelatedDetails April 2023Vol 43, Issue 4 Advertisement Article InformationMetrics © 2023 American Heart Association, Inc.https://doi.org/10.1161/ATVBAHA.122.318548PMID: 36756882 Originally publishedFebruary 9, 2023 Keywordsecho-planar imagingfluorinemitral valve insufficiencyperipheral arterial diseasehypoxiamagnetic resonance imagingPDF download Advertisement SubjectsMagnetic Resonance Imaging (MRI)Peripheral Vascular DiseaseVascular Biology