Session ThOB. There are 6 abstracts in this session.

Session: Experimental MRI, time: 10:45-11:10
Population MR in metabolic diseases: focus on Asian phenotypes
Patrick Cozzone
Singapore Bioimaging Consortium, Singapore, Singapore
The rapid economic growth in Asia has generated more wealth in the population. But as affluence spreads, a pandemic has begun to surface which adversely affects the health and economic capacity of millions of people. That silent debilitating condition is "metabolic diseases". Asians have a diverse genetic make-up which generally differs from their Western counterparts. Such inherited traits predispose Asians to develop non-obese diabetes and its complications such as heart failure, as well as hepatitis-virus driven liver cancer. This lecture aims to highlight methods to help counter this rising menace through relevant human studies, advanced animal models and avant-garde metabolic MR imaging technology.

Session: Experimental MRI, time: 10:45-11:10
Measurement of Stimulated Current Distribution in the Brain with MR Electric Impedance Tomography
Thomas H. Mareci
University of Florida, Gainesville, FL
Transcranial electrical stimulation is indicated for stroke rehabilitation, treatment of epilepsy and possibly cancer, and may improve cognitive, motor or memory performance in healthy subjects. However, the distribution of current and the underlying mechanisms of action remain unclear. This presentation will discuss the use of phase-sensitive magnetic resonance electric impedance tomography to measure the distribution of stimulated currents in the brain and show current density images in human heads. Experimental design is critical, since a low applied transcranial current (~ 1.5 – 2.0 mA) induces a very low local magnetic field in the tissue (less than 2 nT). This require consideration of factors such as SNR in phase-sensitive images, magnetic field stability, and electrode lead-wire placement.

Session: Experimental MRI, time: 11:10-11:35
MRI of Human Brain Microstructure: Bridging microscopic features to millimeter voxels
Jennifer McNab
Stanford University, Stanford, CA
Relaxation and diffusion MRI provide mechanisms for interrogating properties of brain tissue structure at a much smaller scale than the image resolution (i.e. μm vs. mm). This presentation will discuss how the quest for improved biological specificity is moving diffusion MRI of human brain beyond the classic single pulsed Stejskal-Tanner style diffusion encoding to multiple pulsed diffusion encoding and more varied diffusion encoding waveforms. The presentation will also outline efforts to validate the sensitivity of diffusion MRI through direct comparisons to advanced histology and describe a recent study that employed tissue clearing to study the respective contribution of lipids and proteins to relaxation and diffusion MRI contrast.

Session: Experimental MRI, time: 11:35-12:00
Magnetic Resonance in the Human Connectome Project and the BRAIN Initiative Kamil Ugurbil, CMRR, University of Minnesota
Kamil Ugurbil
University of Minnesota, Minneapolis, MN
Bridging and spanning the multiple scales of organization is an essential, but a daunting task necessary for understanding brain function and ultimately dysfunction. Rapid developments in instrumentation for RF transmission and signal detection, a push to achieve higher magnetic fields (currently at 10.5T for human imaging) despite challenges of imaging at the correspondingly high RF frequencies, and a plethora of novel imaging acquisition techniques that increase spatiotemporal sampling has been bringing transformative changes into our ability to map human brain function and connectivity. These developments complemented by other non-MR imaging methods hold the promise that in the near future it will be feasible to integrate information from the level of a single synapse to whole brain networks that define behavior.

Session: Experimental MRI, time: 12:00-12:15
Acoustically Modulated MRI of Gas-filled Protein Nanostructures
George J. Lu1; Arash Farhadi1; Jerzy O. Szablowski1; Audrey Lee-Gosselin1; Samuel Barnes2; Anupama Lakshmanan1; Raymond W. Bourdeau1; Mikhail G. Shapiro1
1California Institute of Technology, Pasadena, CA; 2Loma Linda University, Loma Linda, CA
We introduce gas vesicles (GVs), a class of gas-filled protein-only nanostructures discovered in photosynthetic microbes. While the air-to-water magnetic susceptibility difference enables their T2/T2* contrast, their unique acoustic property allows the use of sub-millisecond ultrasound pulses to erase the contrast in situ, which enables background-free MRI. GVs can be used as reporter genes to image biological processes in living bacteria. Genetic variants of GVs, differing in their magnetic or mechanical properties, allow multiplexed imaging using parametric MRI or differential acoustic sensitivity. Finally, clustering-induced changes in MRI contrast enable the potential design of dynamic molecular sensors. These protein contrast agents, possessing dual responsiveness to MRI and ultrasound, give rise to a new modality for molecular imaging with unique capabilities and advantages.

Session: Experimental MRI, time: 12:15-12:30
Ultrafast Multi-Slice Spatiotemporally Encoded MRI with Simultaneous Echo Refocusing
Shuhui Cai; Yao Luo; Jun Zhang; Congbo Cai
Xiamen University, Xiamen, China
Single-shot spatiotemporally encoded (SPEN) ultrafast MRI is of great value to both scientific research and clinical application. Multi-slice SPEN MRI is a promising supplement to ultrafast multi-slice sampling. In this work, we propose an ultrafast multi-slice SPEN MRI method which produces multiple images within a single train of echoes and successively samples widely separated slices. The resulting images were reconstructed using de-convolution super-resolved algorithm. The robustness and efficiency of the proposed method were demonstrated by phantom, lemon and in vivo experiments. The results indicate that the new method effectively shortens the sampling time and reduces the eddy current effect while maintaining the superiority of SPEN MRI. The new method will promote the versatility of multi-slice MRI in practical applications.