Trong-Kha Truong, Ph.D.[Edit Page]
Instructor, Radiology
ing. phys. dipl. EPF, 2000, Swiss Federal Institute of Technology Lausanne (Physics)
M.S., 2002, The Ohio State University (Biomedical Engineering)
Ph.D., 2004, The Ohio State University (Biomedical Engineering)
Research Statement
My research involves the development of innovative techniques to increase the sensitivity and specificity of functional MRI (fMRI) and diffusion tensor imaging (DTI), as well as novel contrast mechanisms to improve the spatial and temporal localization of neural activity in fMRI.
fMRI and DTI are widely used to investigate neural activity and connectivity noninvasively, but rely on fast imaging sequences, which are vulnerable to artifacts caused by spatial and temporal variations of the static magnetic field (B0) due to susceptibility effects, eddy currents, motion, physiological noise, and system instabilities. To address these issues, we developed a single-shot dual-z-shimmed spiral-in/out imaging technique for effective and efficient signal loss recovery in fMRI [J9]; a comprehensive method for susceptibility- and eddy current-induced distortion correction in DTI [J10]; and a novel k-space energy spectrum analysis approach for inherent and dynamic deblurring in spiral imaging [C26]. Such methods improve the sensitivity, spatial fidelity, and accuracy of fMRI and DTI, thereby increasing their utility for both research and clinical applications, particularly in the challenging pediatric, geriatric, and patient populations.
The blood oxygenation level-dependent (BOLD) contrast is extensively used in fMRI, but its spatial specificity is reduced by signal contributions from vessels of different sizes. An alternative contrast mechanism based on functional changes of the apparent diffusion coefficient (ADC), which can be sensitized to small vessels more closely localized to the neural activity, was previously proposed. We investigated its cortical depth dependence to demonstrate its improved spatial specificity as compared to the BOLD contrast [J12], and developed a single-shot ADC imaging technique to increase the efficiency and accuracy of ADC fMRI [J8].
fMRI techniques relying on secondary hemodynamic modulations (e.g., BOLD) are inherently limited in their ability to accurately localize neural activity in space and time. To address these limitations, we developed a novel technique, termed Lorentz effect imaging, which uses oscillating magnetic field gradients to detect spatially incoherent yet temporally synchronized electrical activity [B1]. We demonstrated its ability to image minute electronic currents in conductive wires with a millisecond temporal resolution [J6], ionic currents in solution with current densities similar to those induced by neural activity [J11], and sensory nerve action potentials in the human median nerve in vivo [J7]. Building upon these promising results, we are further developing this technique for direct MRI of neural activity in the brain. Such a real-time and noninvasive neuroimaging technique could have a significant impact in neurosciences.
Representative Publications
Hayes SM, Baena E, Truong TK, Cabeza R (in press). Neural mechanisms of context effects on face recognition: automatic binding and context shift decrements. J Cog Neurosci.
Truong TK, Song AW (2009). Cortical depth dependence and implications on the neuronal specificity of the functional apparent diffusion coefficient contrast. NeuroImage 47(1): 65-68.
Truong TK, Avram A, Song AW (2008). Lorentz effet imaging of ionic currents in solution. J Magn Reson 191(1): 93-99.
Truong TK, Chen B, Song AW (2008). Integrated SENSE DTI with correction of susceptibility- and eddy current-induced geometric distortions. NeuroImage 40(1): 53-58.
Truong TK, Song AW (2008). Single-shot dual-z-shimmed sensitivity-encoded spiral-in/out imaging for functional MRI with reduced susceptibility artifacts. Magn Reson Med 59(1): 221-227.
Song AW, Guo H, Truong TK (2007). Single-shot ADC imaging for fMRI. Magn Reson Med 57(2): 417-422.
Truong TK, Song AW (2006). Finding neuroelectric activity under magnetic-field oscillations (NAMO) with magnetic resonance imaging in vivo. Proc Natl Acad Sci USA 103(33): 12598-12601.
Truong TK, Wilbur JL, Song AW (2006). Synchronized detection of minute electrical currents with MRI using Lorentz effect imaging. J Magn Reson 179(1): 85-91.
Truong TK, Chakeres DW, Scharre DW, Beversdorf DQ, Schmalbrock P (2006). Blipped multi Gradient Echo Slice Excitation Profile Imaging (bmGESEPI) for fast T2* measurements with macroscopic B0 inhomogeneity compensation. Magn Reson Med 55(6): 1390-1395.
Truong TK, Chakeres DW, Beversdorf DQ, Scharre DW, Schmalbrock P (2006). Effects of static and radiofrequency magnetic field inhomogeneity in ultra-high field magnetic resonance imaging. Magn Reson Imaging 24(2): 103-112.
Truong TK, Clymer BD, Chakeres DW, Schmalbrock P (2002). Three-dimensional numerical simulations of susceptibility-induced magnetic field inhomogeneities in the human head. Magn Reson Imaging 20(10): 759-770.
Song AW, Truong TK, Woldorff M (2009). Dynamic MRI of small electrical activity. In: Hyder F, ed. Dynamic brain imaging: multi-modal methods and in vivo applications. New York, NY: Humana Press. pp. 297-315.
Truong TK, Chen NK, Song AW (2009). Application of k-space energy spectrum analysis for inherent and dynamic B0 mapping and deblurring in spiral imaging. Proc Intl Soc Mag Reson Med 17, Honolulu, HI, p. 2790.