Aerobic life relies on oxygen for respiration and bioenergetic metabolism. Abnormality in the concentration of oxygen in human body is strongly implicated in the pathogenesis of a variety of diseases including cancer, myocardial infarction and stroke. Despite the importance of oxygen, accurate measurement and mapping of tissue oxygenation is difficult. Although many imaging modalities provide only relative or descriptive data on tissue oxygenation, the electron paramagnetic resonance (EPR) spectroscopy has the potential of providing quantitative data of oxygen in tissues, in vivo. In addition, the EPR technique has the unique capability of measuring absolute value of oxygen concentration with resolutions far better than any other technique. This is possible using molecular or crystalline paramagnetic probes whose EPR line-width is sensitive to molecular oxygen. This capability, when combined with the ability to obtain spatially resolved information using spectral-spatial (spectroscopic) EPR imaging, can provide accurate mapping of oxygen concentration. Despite significant advances in the development of highly oxygen-sensitive spin probes and low-frequency imaging instrumentation in the past decade, the use of this important technology for biological applications is severely limited by the prohibitively long acquisition times, usually tens of min. The main objective of this proposal is to develop novel image acquisition and reconstruction strategies to enable fast and high-resolution mapping of oxygen concentration in tissues. The proposal seeks to develop: (1) High-resolution 3D/4D spectroscopic imaging software and techniques for spatial mapping of oxygen concentration in tissues; (2) Fast 3D/4D spectroscopic imaging using spinning/sweeping magnetic field gradients; (3) Direct single-stage image reconstruction algorithm for progressive visualization of images from random-mode acquisitions; (4) Sensitive-mode adaptive data (SMAD) acquisition approach for increased data acquisition efficiency and image resolution; (5) Constant-time spectral-spatial imaging (CT-SSI) methods for fast and high-resolution imaging of oxygen. Preliminary studies show that up to 30-fold increase in the speed of image acquisition can be achieved compared to the conventional methods. The availability of these innovative procedures will enhance our ability to perform fast/high-resolution image acquisition. The technology should offer exciting new opportunities in the field of biomedical imaging of free radicals and oxygen.
| Vikram, Deepti S; Rivera, Brian K; Kuppusamy, Periannan (2010) In vivo imaging of free radicals and oxygen. Methods Mol Biol 610:3-27 |
| Som, Subhojit; Potter, Lee C; Ahmad, Rizwan et al. (2008) EPR oximetry in three spatial dimensions using sparse spin distribution. J Magn Reson 193:210-7 |
| Ahmad, Rizwan; Vikram, Deepti S; Potter, Lee C et al. (2008) Estimation of mean and median pO2 values for a composite EPR spectrum. J Magn Reson 192:269-74 |
| Deng, Yuanmu; Petryakov, Sergy; He, Guanglong et al. (2007) Fast 3D spatial EPR imaging using spiral magnetic field gradient. J Magn Reson 185:283-90 |
| Ahmad, Rizwan; Vikram, Deepti S; Clymer, Bradley et al. (2007) Uniform distribution of projection data for improved reconstruction quality of 4D EPR imaging. J Magn Reson 187:277-87 |
| Som, Subhojit; Potter, Lee C; Ahmad, Rizwan et al. (2007) A parametric approach to spectral-spatial EPR imaging. J Magn Reson 186:1-10 |
| Bratasz, Anna; Pandian, Ramasamy P; Deng, Yuanmu et al. (2007) In vivo imaging of changes in tumor oxygenation during growth and after treatment. Magn Reson Med 57:950-9 |
| Vikram, Deepti S; Zweier, Jay L; Kuppusamy, Periannan (2007) Methods for noninvasive imaging of tissue hypoxia. Antioxid Redox Signal 9:1745-56 |
| Ahmad, Rizwan; Deng, Yuanmu; Vikram, Deepti S et al. (2007) Quasi Monte Carlo-based isotropic distribution of gradient directions for improved reconstruction quality of 3D EPR imaging. J Magn Reson 184:236-45 |
| Ahmad, Rizwan; Clymer, Bradley; Vikram, Deepti S et al. (2007) Enhanced resolution for EPR imaging by two-step deblurring. J Magn Reson 184:246-57 |
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