Title: Assistant Professor
Phone: (919) 962-2229
Web page: https://brancagroup.web.unc.edu/
My research focuses on the development of new approaches and methodologies for Magnetic Resonance Imaging (MRI) and Nuclear Magnetic Resonance (NMR) spectroscopy that can be used for clinical research and diagnoses, with a special emphasis on hyperpolarized gas and non-linear magnetic resonance effects.
Hyperpolarized gas MRI
By combining hyperpolarized gas MR imaging with magnetic nanoprobes, my group has recently developed a method to specifically tag and detect cancer cells in the lungs. Monte Carlo simulations are currently employed to study the effect of these nanoprobes on HP gas inside the highly inhomogeneous lung environment. The goal is to model and understand the spin dephasing caused by the magnetic nanoprobes to design new imaging approaches that improve resolution and sensitivity.
Our research with hyperpolarized gas has recently moved beyond lung imaging. My lab is now exploiting the high solubility of 129Xe gas in biological tissue and its sensitivity to the local chemical environment to obtain structural and functional information of tissues that cannot be obtained with conventional proton-based MRI methods.
Investigation of non-linear spin dynamics
At high magnetic fields, non-linear NMR effects contribute significantly to the detected signal from highly polarized samples (such as humans at normal clinical field strength, as they consist of more than 70% water). Theoretically, these effects can be explained classically by the action of the Distant Dipolar Field (DDF) or, quantum mechanically, by intermolecular multiple-quantum coherences (iMQC). These coherences have special properties, such as insensitivity to local magnetic field inhomogeneities and high sensitivity to tissue structure. We use these properties to enhance MR image contrast and to improve resolution in in vivo MR spectroscopy.
A. Khanna, R.T. Branca, “Detecting brown adipose tissue activity with BOLD MRI in mice”, Magn. Reson. in Medicine, published online (2012). PMID: 22231619
R.T. Branca, “MRI using intermolecular multiple-quantum coherences”, Methods Mol Biol. 771:241-52 (2011). PMID: 21874482
R.T. Branca, W.S. Warren, “In vivo brown adipose tissue detection and characterization using water-lipid intermolecular zero-quantum coherences”, Magn Reson Med, 65 (2), 313-9 (2011). PMID: 20939093
R.T. Branca, W.S. Warren, “In vivo NMR detection of diet induced changes in adipose tissue composition”, J Lipid Res, 52 (4), 833-9 (2011). PMID: 21270099
R.T. Branca, E.R. Jenista, W.S. Warren, “Inhomogeneity-free heteronuclear iMQC”, J Magn Reson, 209 (2), 347-51 (2011). PMID: 21316278
E.R. Jenista, R.T. Branca, W.S. Warren, “Absolute temperature imaging using intermolecular multiple quantum MRI”, Int J Hyperthermia, 26 (7), 725-34 (2010) PMID: 20849265
E.R. Jenista, G. Galiana, R.T. Branca, P.S. Yarmolenko, A.M. Stokes, M. W. Dewhirst, W.S. Warren, “Application of mixed spin iMQCs for temperature and chemical-selective imaging”, J. Magn. Reson. 204 (2), 208-18 (2010). PMID: 20303808
E.R. Jenista, A.M. Stokes, R.T. Branca, W.S. Warren, “Optimized, unequal pulse spacing in multiple echo sequences improves refocusing in magnetic resonance”, J. Chem. Phys.131(20):204510 (2009). PMID: 19947697
R.T. Branca, Z.I. Cleveland, B. Fubara, C. Kumar, C. Leuschner, R.R. Maronpot, W.S. Warren, B. Driehuys, “Molecular MRI for sensitive and specific detection of lung metastases”, PNAS 107(8):3693-7. PMID: 20142483
W.S. Warren, E.R. Jenista, R.T. Branca, “Increasing hyperpolarized spin lifetimes through true singlet eigenstates”, Science 323(5922), 1711-1714 (2009). PMID: 19325112
R.T. Branca, W. S. Warren, “Solvent suppression without crosspeak attenuation in iZQC experiments”, Chem. Phys. Lett., 470(4-6), 325-331 (2009).
R.T. Branca, Y. M. Chen, V. Mouraviev, G. Galiana, E. Jenista, C. Kumar, C. Leuschner, W. S. Warren, “iDQC anisotropy map imaging for tumor tissue characterization in vivo”, Magn. Reson. in Med. 61(4), 937 – 943 (2009). PMID: 19215050
E.R. Jenista, R.T. Branca, and W.S. Warren, “Hyperpolarized Carbon-Carbon Intermolecular Multiple Quantum Coherences,” J. Magn. Reson., 196(1), 74-77 (2008). PMID: 18926750
G. Galiana, R.T. Branca, E.R. Jenista, and W.S. Warren, “Accurate Temperature Imaging Based on Intermolecular Coherences in Magnetic Resonance,” Science 322(5900), 421-424 (2008). PMID: 18927389
R.T. Branca, G. Galiana, W. S. Warren, “Enhanced Nonlinear Magnetic Resonance signals via Square Wave Dipolar Fields”, J. Chem. Phys. 129, 054502 (2008). PMID: 18698909
R.T. Branca, G. Galiana, W. S. Warren, “Signal Enhancement in CRAZED Experiments”, J. Magn. Reson. 187(1):38-43 (2007). PMID: 17448714
G. Galiana, R.T. Branca, and W. S. Warren, “Ultrafast Intermolecular Zero Quantum Spectroscopy”, J. Am. Chem. Soc. 21;127(50):17574-5 (2005)
K. L. Shannon, R.T Branca, et al., “Simultaneous Acquisition of Multiple Orders of Intermolecular Multiple-Quantum Coherence Images in Vivo”, Magn. Reson. Imaging 22(10):1407-12 (2004)
R.T. Branca, S. Capuani,B. Maraviglia, “About the Crazed Sequence”, Conc. In Magn. Reson. Part A, 21A, 1:22-36 (2004)
S. Capuani, M. Alesiani, R.T. Branca, B. Maraviglia, “New openings for porous systems research from intermolecular double-quantum NMR”, Solid State Nucl Magn. Reson. 25(1-3):15 9(2004).
F. Fasano, S. Capuani, G. E. Hagberg, R.T. Branca, I. Indovina, A. Castriota-Scanderberg, B. Maraviglia, “Intermolecular double-quantum coherences (iDQC) and diffusion weighted imaging (DWI) imaging of the human brain at 1.5T”, Magn. Reson. Imaging 21(10):1151-7 (2003).
S. Capuani, R.T. Branca, M. Alesiani, B. Maraviglia, “Intermolecular double-quantum NMR techniques to probe microstructures on porous media”, Magn. Reson. Imaging (3-4): 413-4(2003).