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Phillip Zhe Sun, PH.D.

TitleAssistant Professor of Radiology
InstitutionMassachusetts General Hospital
DepartmentRadiology
AddressMassachusetts General Hospital
Radiology, Rm. 2301
149 13th Street
Charlestown MA 02129
Phone617/726-4060
Fax617/726-7422

 Overview 
 overview
My research is to develop and apply novel MRI technique to improve our understanding of human diseases for early diagnosis and treatment. In particular, I have been focusing on imaging ischemic penumbra (the viable tissue under the risk of infarction if not reperfused promptly) using the recently developed pH sensitive endogenous amide proton transfer (APT) MRI. Conventionally, perfusion (PWI) and diffusion (DWI) imaging can demarcate ischemic core from hypoperfused area, which contains both ischemic penumbra and benign oligaemia. As the thrombolytic treatment increases the risk of hemorrhage and has neurotoxic side effects, it is crucial to detect the ischemic penumbra to assist treatment decision. Previously, we showed that pH MRI, in complimentary to PWI and DWI can delineate the ischemic tissue into core, penumbra and benign oligaemia, and the pH lesion is closely correlated with the 24hr infarction using a permanent animal stroke model. Encouraged by the animal study, we have implemented and optimized the APT imaging on clinical scanners, and are currently evaluating its effectiveness in detecting salvageable ischemic tissue on acute and subacute stroke patients. We will also develop and validate an infarction prediction model that integrates multi-parametric MRI of the hemodynamic, metabolic, structural and temporal status of ischemic tissue, and the ultimate goal is to develop MRI guided acute stroke therapy.

I am also interested in advancing the new chemical exchange dependent saturation transfer (CEST) imaging for specific molecular and cellular MRI. In comparison with conventional relaxation based contrast agents, the CEST agents can be incorporated into cellular proteins and provide enormous amplification of dilute labile groups. We will develop sensitive CEST agents that specifically bind to cell surface markers and explore the CEST imaging as a new method for cell tracking and functional imaging.

Moreover, I am developing advanced diffusion MRI technique such as diffusion imaging with ultra-short diffusion time. Although diffusion MRI has found tremendous applications such as white matter fiber tracking and detection of early stroke lesion, one of the technical limits is that the diffusion time is usually very long, tens of milliseconds, therefore the diffusion imaging is susceptible to transmembrane exchange and displacement restriction. By developing a diffusion MRI of ultra-short diffusion time, we can provide “genuine” diffusion contrast of microscopic water mobility and therefore improve our understanding of diffusion change in response tissue damage. In addition, I am also exploring a hybrid MRI technique that integrates the magnetization transfer and intravoxel incoherent motion (IVIM) mechanism as a new technique for endogenous cerebral blood volume (CBV) imaging.


 Bibliographic 
 selected publications
Publications listed below are automatically derived from MEDLINE/PubMed and other sources, which might result in incorrect or missing publications. Faculty can login to make corrections and additions.
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  1. Sun PZ, Lu J, Wu Y, Xiao G, Wu R. Evaluation of the dependence of CEST-EPI measurement on repetition time, RF irradiation duty cycle and imaging flip angle for enhanced pH sensitivity. Phys Med Biol. 2013 Sep 7; 58(17):N229-40.
    View in: PubMed
  2. Sun PZ, Wang Y, Xiao G, Wu R. Simultaneous experimental determination of labile proton fraction ratio and exchange rate with irradiation radio frequency power-dependent quantitative CEST MRI analysis. Contrast Media Mol Imaging. 2013 May; 8(3):246-51.
    View in: PubMed
  3. Cheung JS, Wang E, Lo EH, Sun PZ. Stratification of heterogeneous diffusion MRI ischemic lesion with kurtosis imaging: evaluation of mean diffusion and kurtosis MRI mismatch in an animal model of transient focal ischemia. Stroke. 2012 Aug; 43(8):2252-4.
    View in: PubMed
  4. Wu R, Liu CM, Liu PK, Sun PZ. Improved measurement of labile proton concentration-weighted chemical exchange rate (k(ws)) with experimental factor-compensated and T(1) -normalized quantitative chemical exchange saturation transfer (CEST) MRI. Contrast Media Mol Imaging. 2012 Jul-Aug; 7(4):384-9.
    View in: PubMed
  5. Zhang L, Jiang B, Wu Y, Strouthos C, Sun PZ, Su J, Zhou X. Developing a multiscale, multi-resolution agent-based brain tumor model by graphics processing units. Theor Biol Med Model. 2011; 8:46.
    View in: PubMed
  6. Sun PZ, Wang E, Cheung JS. Imaging acute ischemic tissue acidosis with pH-sensitive endogenous amide proton transfer (APT) MRI--correction of tissue relaxation and concomitant RF irradiation effects toward mapping quantitative cerebral tissue pH. Neuroimage. 2012 Mar; 60(1):1-6.
    View in: PubMed
  7. Sun PZ. Simplified quantification of labile proton concentration-weighted chemical exchange rate (k(ws) ) with RF saturation time dependent ratiometric analysis (QUESTRA): normalization of relaxation and RF irradiation spillover effects for improved quantitative chemical exchange saturation transfer (CEST) MRI. Magn Reson Med. 2012 Apr; 67(4):936-42.
    View in: PubMed
  8. Cheung JS, Wang E, Zhang X, Mandeville E, Lo EH, Sorensen AG, Sun PZ. Fast radio-frequency enforced steady state (FRESS) spin echo MRI for quantitative T2 mapping: minimizing the apparent repetition time (TR) dependence for fast T2 measurement. NMR Biomed. 2012 Feb; 25(2):189-94.
    View in: PubMed
  9. Sun PZ, Wang E, Cheung JS, Zhang X, Benner T, Sorensen AG. Simulation and optimization of pulsed radio frequency irradiation scheme for chemical exchange saturation transfer (CEST) MRI-demonstration of pH-weighted pulsed-amide proton CEST MRI in an animal model of acute cerebral ischemia. Magn Reson Med. 2011 Oct; 66(4):1042-8.
    View in: PubMed
  10. Sun PZ, Cheung JS, Wang E, Lo EH. Association between pH-weighted endogenous amide proton chemical exchange saturation transfer MRI and tissue lactic acidosis during acute ischemic stroke. J Cereb Blood Flow Metab. 2011 Aug; 31(8):1743-50.
    View in: PubMed
  11. Sun PZ, Benner T, Copen WA, Sorensen AG. Early experience of translating pH-weighted MRI to image human subjects at 3 Tesla. Stroke. 2010 Oct; 41(10 Suppl):S147-51.
    View in: PubMed
  12. Sun PZ, Cheung JS, Wang E, Benner T, Sorensen AG. Fast multislice pH-weighted chemical exchange saturation transfer (CEST) MRI with Unevenly segmented RF irradiation. Magn Reson Med. 2011 Feb; 65(2):588-94.
    View in: PubMed
  13. Sun PZ. Simplified and scalable numerical solution for describing multi-pool chemical exchange saturation transfer (CEST) MRI contrast. J Magn Reson. 2010 Aug; 205(2):235-41.
    View in: PubMed
  14. Jin G, Sun PZ, Singhal AB, Ayata C, Lo EH. First-order mathematical modeling of brain swelling in focal cerebral ischemia. Transl Stroke Res. 2010 Mar; 1(1):65-70.
    View in: PubMed
  15. Sun PZ. Simultaneous determination of labile proton concentration and exchange rate utilizing optimal RF power: Radio frequency power (RFP) dependence of chemical exchange saturation transfer (CEST) MRI. J Magn Reson. 2010 Feb; 202(2):155-61.
    View in: PubMed
  16. Sun PZ, Benner T, Kumar A, Sorensen AG. Investigation of optimizing and translating pH-sensitive pulsed-chemical exchange saturation transfer (CEST) imaging to a 3T clinical scanner. Magn Reson Med. 2008 Oct; 60(4):834-41.
    View in: PubMed
  17. Sun PZ, Sorensen AG. Imaging pH using the chemical exchange saturation transfer (CEST) MRI: Correction of concomitant RF irradiation effects to quantify CEST MRI for chemical exchange rate and pH. Magn Reson Med. 2008 Aug; 60(2):390-7.
    View in: PubMed
  18. Salhotra A, Lal B, Laterra J, Sun PZ, van Zijl PC, Zhou J. Amide proton transfer imaging of 9L gliosarcoma and human glioblastoma xenografts. NMR Biomed. 2008 Jun; 21(5):489-97.
    View in: PubMed
  19. Sun PZ, Benner T, Sorensen AG. An Investigation of Optimizing and Translating Pulsed-Chemical Exchange Saturation Transfer (CEST) Imaging to a 3 T Clinical Scanner. 16th ISMRM. 2008.
  20. Sun PZ, Farrar C, Sorensen AG. Correction for Artifacts Induced by B0 and B1 Field Inhomogeneities in Chemical Exchange Saturation Transfer (CEST) MRI. 16th ISMRM. 2008.
  21. Sun PZ, Murata Y, Lu J, Wang X, Lo EH, Sorensen AG. Relaxation-compensated fast multislice amide proton transfer (APT) imaging of acute ischemic stroke. Magn Reson Med. 2008 May; 59(5):1175-82.
    View in: PubMed
  22. Zhu HH, Liu JX, Murata Y, Yu ZY, Sun PZ, Lu J, Lo EH, Wang XY. Annesin II combined with low dose tPA improves neurological outcomes in embolic stroke model of rats. American Heart Association, International Stroke Conference. 2008.
  23. Song YQ, Cho H, Hopper T, Pomerantz AE, Sun PZ. Magnetic resonance in porous media: recent progress. J Chem Phys. 2008 Feb 7; 128(5):052212.
    View in: PubMed
  24. Sun PZ, Farrar CT, Sorensen AG. Correction for artifacts induced by B(0) and B(1) field inhomogeneities in pH-sensitive chemical exchange saturation transfer (CEST) imaging. Magn Reson Med. 2007 Dec; 58(6):1207-15.
    View in: PubMed
  25. Hua J, van Zijl P, Sun PZ, Zhou J. Quantitative Description of Magnetization Transfer (MT) Asymmetry in Experimental Brain Tumors. Proc. Intl. Soc. Mag. Reson. Med. 15. 2007; 882.
  26. Zhou J, Salhotra A, Sun PZ, Lal B, Laterra J, van Zijl, P. Amide Proton Transfer Imaging and Magnetization Transfer Imaging for Characterizing Rat Brain Tumors. Proc. Intl. Soc. Mag. Reson. Med. 15. 2007; 2996.
  27. Sun PZ, Sorensen AG. Improved Quantification of Diffusion in Heterogeneous Systems Using the New Magic Asymmetric Gradient (MAG) Technique. Proc. Intl. Soc. Mag. Reson. Med. 15. 2007; 3540.
  28. Sun PZ, Zhou J, Huang J, Benner T, Sorensen AG, van Zijl P. Amide Proton Transfer (APT) Imaging Using Saturation Transfer Versus Inversion Transfer -- Which Is Better?. Proc. Intl. Soc. Mag. Reson. Med. 15. 2007; 3455.
  29. Sun PZ, Zhou J, Mcmahon M, van Zijl P . Optimal Properties of Chemical Exchange Saturation Transfer (CEST) Contrast Agents. Proc. Intl. Soc. Mag. Reson. Med. 15. 2007; 3404.
  30. Sun PZ. Improved diffusion measurement in heterogeneous systems using the magic asymmetric gradient stimulated echo (MAGSTE) technique. J Magn Reson. 2007 Aug; 187(2):177-83.
    View in: PubMed
  31. Sun PZ, Huang J, Zhou JY, van Zijl P and Sorensen AG. pH sensitive MRI as a new imaging signature for acute ischemia. 31st Annual MGH Research Symposium and Poster Session. 2007; 12.
  32. Sun PZ, Zhou J, Huang J, van Zijl P. Simplified quantitative description of amide proton transfer (APT) imaging during acute ischemia. Magn Reson Med. 2007 Feb; 57(2):405-10.
    View in: PubMed
  33. Song YQ, Cho H, Hopper T, Pomerantz A, Sun PZ. Magnetic resonance in porous media: recent progress. J. Chem. Physics. 2007; accepted.
  34. Sun PZ, Zhou J, Sun W, Huang J, van Zijl PC. Detection of the ischemic penumbra using pH-weighted MRI. J Cereb Blood Flow Metab. 2007 Jun; 27(6):1129-36.
    View in: PubMed
  35. McMahon MT, Gilad AA, Zhou J, Sun PZ, Bulte JW, van Zijl PC. Quantifying exchange rates in chemical exchange saturation transfer agents using the saturation time and saturation power dependencies of the magnetization transfer effect on the magnetic resonance imaging signal (QUEST and QUESP): Ph calibration for poly-L-lysine and a starburst dendrimer. Magn Reson Med. 2006 Apr; 55(4):836-47.
    View in: PubMed
  36. Sun PZ, Zhou JY, Sun WY, Huang J and van Zijl PC. Delineating the Boundary between the Ischemic Penumbra and Regions of Oligaemia Using pH-weighted MRI (pHWI). Proc. Intl. Soc. Mag. Reson. Med. (14). 2006; 615.
  37. Salhotra A, Sun PZ, van Zijl P, Bhujwalla Z, Lal B, Laterra J and Zhou JY. Blood Flow Increase in Brain Tumor in Response to Radiation Therapy and Chemotherapy as Detected by Arterial Spin Labeling MRI. Proc. Intl. Soc. Mag. Reson. Med. (14). 2006; 1765.
  38. Sun PZ. Accurate Quantification of Diffusion in Heterogeneous Systems Using the New Magic Asymmetric Gradient (MAG) Technique. Proc. Intl. Soc. Mag. Reson. Med. (14). 2006; 1054.
  39. Sun PZ, Zhou JY, Huang J, van Zijl P. Power Optimization of in-vivo Chemical Exchange Saturation Transfer (CEST) contrast for pH weighted Imaging. Proc. Intl. Soc. Mag. Reson. Med. 14. 2006; 105.
  40. Sun PZ, van Zijl PC, Zhou J. Optimization of the irradiation power in chemical exchange dependent saturation transfer experiments. J Magn Reson. 2005 Aug; 175(2):193-200.
    View in: PubMed
  41. Sun PZ, Zhou J, Sun W, Huang J, van Zijl PC. Suppression of lipid artifacts in amide proton transfer imaging. Magn Reson Med. 2005 Jul; 54(1):222-5.
    View in: PubMed
  42. Sun PZ, Zhou JY, Sun WY, Huang J, van Zijl P. Characterization the evolution of ischemic penumbra using pH-weighted imaging. Journal of Cerebral Blood Flow & Metabolism. 2005; 457.
  43. Zhou JY, Salhotra A, Sun PZ, Lal B, van Zijl P, Laterra J. Detecting brain tumor therapy response using amide proton transfer contrast. Proc. Intl. Soc. Mag. Reson. Med. (13). 2005; 243.
  44. Sun PZ, Zhou JY, Sun WY, Huang J, van Zijl P. Characterization the evolution of ischemic penumbra using pH-weighted imaging. Proc. Intl. Soc. Mag. Reson. Med. (13). 2005; 984.
  45. Hua J, Sun PZ, Johns CK, van Zijl PC and Zhou JY. Amide proton transfer imaging contrast in the brain and saturation power optimization. 46th Experimental Nuclear Magnetic Resonance Conference. 2005; 19.
  46. Sun PZ, Zhou JY, Sun WY, Huang J, van Zijl P. Characterization the evolution of ischemic penumbra using pH-weighted imaging. Journal of Cerebral Blood Flow & Metabolism. 2005; 25:457.
  47. Sun PZ, Zhou JY, Sun WY, Huang J, van Zijl P. Lipid artifact suppression in amide proton transfer (APT) EPI imaging. Proc. Intl. Soc. Mag. Reson. Med. (13). 2005; 2212.
  48. Sun PZ, Smith SA, Zhou J. Analysis of the magic asymmetric gradient stimulated echo sequence with shaped gradients. J Magn Reson. 2004 Dec; 171(2):324-9.
    View in: PubMed
  49. Zhou J, Wilson DA, Sun PZ, Klaus JA, Van Zijl PC. Quantitative description of proton exchange processes between water and endogenous and exogenous agents for WEX, CEST, and APT experiments. Magn Reson Med. 2004 May; 51(5):945-52.
    View in: PubMed
  50. Zhou J, Sun PZ, van Zijl PC. Quantitative Description of Proton Exchange Processes between Water and Endogenous and Exogenous Agents. The sensitivity of PH Imaging using Endogenous Amide Proton Transfer (APT) Contrast. Proc. Intl. Soc. Mag. Reson. Med. (11). 2004; 180.
  51. Hills AJ, Prabhakaran V, Lu HZ, Sun PZ, van Zijl P. fMRI BOLD effect in response to word generation in regions of baseline hypoperfusion (but no infarct) among patients with large vessel arterial stenosis. Scientific Sessions of American Heart Association. 2004.
  52. Prabhakaran V, Raman SP, Grunwald MR, Mahadevia A, Werner JK, Philipose LE, Hussain N, Alphs HH, Sun PZ, Barker PB, Wityk RJ, Rypma B, Hillis AE. Neural Substrates Involved in Conginition for Stroke Patients and Control Subjects. Annual Meeting of Cognitive Neuroscience Society. 2004; 40.
  53. Sun PZ, Seland JG, Cory D. Background gradient suppression in pulsed gradient stimulated echo measurements. J Magn Reson. 2003 Apr; 161(2):168-73.
    View in: PubMed
  54. Sun PZ, Schoening ZB, Jasanoff A. In vivo oxygen detection using exogenous hemoglobin as a contrast agent in magnetic resonance microscopy. Magn Reson Med. 2003 Apr; 49(4):609-14.
    View in: PubMed
  55. Phillip Zhe Sun. NMR diffusion and microscopy. 2003.
  56. Jasanoff A, Sun PZ. In vivo magnetic resonance microscopy of brain structure in unanesthetized flies. J Magn Reson. 2002 Sep-Oct; 158(1-2):79-85.
    View in: PubMed
  57. Sun PZ, Jasanoff A and Cory DG. Q-space imaging and Nuclear Magnetic Resonance microscopy. 43rd Experimental Nuclear Magnetic Resonance Conference. 2002; 202.
  58. Moore A, Sun PZ, Cory D, Högemann D, Weissleder R, Lipes MA. MRI of insulitis in autoimmune diabetes. Magn Reson Med. 2002 Apr; 47(4):751-8.
    View in: PubMed
  59. Sun PZ, Cory DG. Nuclear Magnetic Resonance (NMR) multiple dimensional diffusive scattering. 42nd Experimental Nuclear Magnetic Resonance Conference. 2001; 230.
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