Research

The Biomedical Magnetic Resonance Laboratory (BMRL) and its collaborators are focused on the development and application of magnetic resonance spectroscopy (MRS) and imaging (MRI) for study of intact biological systems. A major area of BMRL research is the development of MR techniques that will provide a more complete understanding of the complex microstructure and governing biophysical and physiologic determinants of mammalian tissues in the intact, functioning state.

One primary focus is the use of water diffusion sensitive MR methods to probe tissue architecture and microstructure at the micron length scale, far less than the actual voxel resolution of the image itself. Tissue microstructure at the micron scale is extraordinarily sensitive to physiologic change and challenge, either normal or pathologic. We seek to elucidate the biophysical phenomena behind the striking changes of water diffusion associated with a variety of normal and pathologic states, with specific focus on cancer, neurodegenerative diseases, and developmental neurobiology. Experiments exploit carefully-chosen model systems ranging from single cells (Xenopus oocytes), to populations of cultured cells (HeLa cells), to small animals (mice, rats), to non-human primates, to humans. In addition, a concerted effort is underway to develop the theoretical means by which to quantitatively describe the effect on the MR diffusion signal of various structural barriers that hinder/restrict the incoherent displacement motion of water.

A second focus exploits biologically compatible agents that affect the MR relaxation properties of tissue water. Relaxation agents can be employed to monitor water exchange between compartments, to probe tissue vascular properties (architecture, permeability, blood flow), and to target and identify cell and tissue types. An emphasis is on cancer, neurodegenerative and cardiovascular disease, and quantitative compartmental modeling of the MR signal in terms tissue-specific water properties.
“Diffusion tensor magnetic resonance imaging of primate brain shows addition of myelin to neural tracks during fetal development.”

Selected Publications

• Jespersen, S.N.; Kroenke, C.D.; Ostergaard, L.; Ackerman, J.J.H.; Yablonskiy, D.A.; "Modeling dendrite density from magnetic resonance diffusion measurements," NeuroImage (2006) in press.
• Zhao, L.; Kroenke, C.D.; Song, J.; Piwnica-Worms, D.; Ackerman, J.J.H.; Neil, J.J.; "Intracellular water specific MR of microbead-adherent cells: the HeLa cell intracellular water exchange lifetime." NMR Biomed. (2006) in press.
• Zhu, M.; Ackerman, J.J.H.; Sukstanskii, A.L.; Yablonskiy, D.A.; "How the body controls brain temperature: the temperature shielding effect of cerebral blood flow," J. App. Physiol. (2006) 101 1481-1488.
• Goodman, J.; Ackerman, J.J.H.; Neil, J.J.; "The sodium ion apparent diffusion coefficient in living rat brain," Magn. Reson. Med. (2005) 53 1040-1045.
• Kroenke, C.D.; Ackerman, J.J.H.; Yablonskiy, D.A.; "On the nature of the NAA diffusion attenuated MR Signal in the central nervous system," Magn. Reson. Med. (2004) 52 1052-1059.