Imaging Microstructure and Dynamics with MR: From Macro to Nano
Recent developments in MRI hardware, magnetic field gradient and radio frequency (RF) pulse sequences, coupled with image processing and imaging sciences advances, have enabled us “drill down” into the imaging voxel to characterize key features of brain microstructure, and increasingly, cell and tissue water dynamics in vivo. Diffusion MRI methods provide an eloquent and elegant way to explore tissue microstructure, architecture, and organization ranging from molecular to macroscopic or whole-body length scales. Complementary multi-dimensional spectroscopic MRI methods are also enabling us to study water exchange and relaxation processes. Collectively, these approaches provide new ways to probe cell and tissue-level processes non-invasively and in vivo. One goal of this research is to develop new quantitative imaging biomarkers for a wide range of neuroscience and clinical applications.
Peter Basser received his A.B., S.M., and Ph.D. degrees in Engineering Sciences from Harvard University, and received his post-doctoral research training within the NIH Intramural Research Program in what is now the National Institute of Biomedical Imaging and Bioengineering (NIBIB). He later became a Senior Investigator at the NIH, and was appointed Head, Section on Tissue Biophysics and Biomimetics (’97), and Director, Program on Pediatric Imaging and Tissue Sciences (’10) within the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD). In 2015, Dr. Basser became Associate Scientific Director (ASD) of the Division of Imaging, Behavior and Genomic Integrity (DIBGI) within NICHD.
Dr. Basser played a principal role in inventing several widely used MRI technologies, including diffusion tensor MRI (DTI) (’91), DTI “streamline tractography” (’91, ’94, ’98), and AxCaliber (’03)—an in vivo MRI method to measure the axon diameter distribution within white matter fascicles and peripheral nerves. His more recent work helped lay the foundation for the field of “in vivo MRI histology” or “microstructure imaging”—developing and translating novel quantitative imaging biomarkers (primarily based upon single and multiple pulsed-field gradient (PFG) MRI methods) to measure and map key histological features in vivo, which pathologists would otherwise laboriously obtain ex vivo. In neuroengineering, Dr. Basser published the first paper on what was later named “convection-enhanced delivery” (CED) (’92). He also helped explain the biophysical basis of “magnetic stimulation” (’90), which led to the first application of transcranial magnetic stimulation (TMS) to treat clinical depression (’93, ’95).