Code: TOB	Time Slot/Poster Number: 10:45-11:10	Session: Advances in Imaging Techniques
The Complexity of Dendritic Arbors in the Developing Cerebral Cortex Determined by Diffusion Tensor Magnetic Resonance Imaging
Lindsey Leigland1; Sune Jespersen2; Erin Taber1; Andrew Bock3; Anda Cornea1; Jaime Olavarria3; Christopher Kroenke1
1Oregon Health and Science University, Portland, OR; 2Aarhus University, Aarhus, Denmark; 3University of Washington, Seattle, WA
Abstract
Cerebral cortical neurons with abnormally low dendritic arbor complexity are commonly observed morphological characteristics of individuals affected by a wide array of neurodevelopmental disorders. Here, progress toward utilization of diffusion tensor magnetic resonance imaging (DTI) to detect abnormal differentiation of neurons in the developing cerebral cortex is described. Empirical evidence linking DTI observables to neuronal morphology is presented; a quantitative model of water diffusion within cortical tissue is derived and experimentally validated; and data from an animal model of a neurodevelopmental disorder is shown to exhibit abnormal morphological development by DTI. These data suggest a non-invasive strategy exists to monitor an aspect of brain development that has traditionally been accessible through histological investigations of post-mortem tissue.

Code: TOB	Time Slot/Poster Number: 11:10-11:25	Session: Advances in Imaging Techniques
Inflammation quantification in intact tissue samples via macrophage labeling with perfluorocarbon followed by 19F NMR: Results in model of MS
Eric Ahrens; Lisa Pusateri; Hongyan Xu; Won-Bin Young
Carnegie Mellon University, Pittsburgh, PA
Abstract
Rapid, quantitative scoring of inflammation in tissue specimens is a common need in many facets of biomedical research. We describe a high-throughput approach to rapidly and quantitatively assay macrophage infiltration in intact tissue samples. We utilize a perfluorocarbon (PFC) nanoemulsion that labels phagocytic leukocytes in vivo, and 19F NMR spectroscopy is used as a quantitative readout of tissue inflammation. We apply this to experimental allergic encephalomyelitis (EAE) rats, a model for multiple sclerosis. We used 19F NMR to calculate an ‘inflammation index’ (IFI) of spinal cord segments. The IFI correlated to mRNA levels of macrophage, and histology confirmed co-localization of the PFC within macrophage.

Code: TOB	Time Slot/Poster Number: 11:25-11:40	Session: Advances in Imaging Techniques
Optimal control excitation for discriminating between fast and slow sodium in tissues
Jae-Seung Lee1, 2; Ravinder Regatte2; Alexej Jerschow1
1New York University, New York, NY; 2New York University Langone Medical Center, New York, NY
Abstract
A variety of tissues and organs have a large amount of sodium ions. With the advent of high-field MRI scanners, high-resolution sodium images can be obtained within clinically acceptable scan times, which makes 23Na MRI a promising tool for the diagnosis of some important diseases. The sodium ions bound to tissues and organs may be subject to slow motion, and quarupolar relaxation can be their dominant relaxation mechanism, which can be used to distinguish bound sodium ions from free ones without quadrupolar relaxation. Here, we present optimal pulses suppressing the signal from free sodium ions and maximizing the signal from bound sodium ions, which are potentially useful for 23Na MRI application.

Code: TOB	Time Slot/Poster Number: 11:40-11:55	Session: Advances in Imaging Techniques
Unequal Echo Spacing Improves MRI Signals and Multiple Quantum Images
Ashley Stokes; Yesu Feng; Elizabeth Jenista; Rosa T. Branca; Warren Warren
Duke University, Durham , NC
Abstract
We present in vivo results in different tissue types showing signal enhancement from the UDD sequence (Uhrig’s Dynamical Decoupling, which has unequal pulse spacing) compared to spin echo and Carr-Purcell-Meiboom-Gill (CPMG) sequences. While CPMG sequences provide improved refocusing in tissue over spin echo sequences, the astonishing result is that the CPMG sequence is not the global optimum. Using the UDD sequence, we have shown signal improvements in numerous tissues for conventional imaging and multiple quantum applications. The UDD sequence performance seems to depend strongly on the number of the pulses used, the sequence parameters, and the tissue microstructure. Theoretical treatments that include RF inhomogeneity, effects of slice selection, and other sequence non-idealities will be presented to explain our observations.

Code: TOB	Time Slot/Poster Number: 11:55-12:20	Session: Advances in Imaging Techniques
Characterization of White Matter Structure with Diffusional Kurtosis Imaging
Jens Jensen; Mariana Lazer; Els Fieremans; Ali Tabesh; Caixia Hu; Maria Falangola; Joseph Helpern
Radiology, New York University School of Medicine, New York, NY
Abstract
Diffusional kurtosis imaging (DKI) is an extension of diffusion tensor imaging (DTI) that allows for the quantification diffusional non-Gaussianity. In particular, DKI provides an estimate for the kurtosis of the diffusion displacement probability distribution. From this diffusional kurtosis, a number of additional diffusion metrics can be calculated, which may be used to better characterize white matter structure. Examples include the application of the mean kurtosis as a measure of diffusional heterogeneity and DKI-based fiber tracking, which can improve upon conventional DTI-based fiber tracking in being able to resolve fiber crossings. A key advantage of DKI is that a whole brain dataset may be acquired using standard diffusion-weighted imaging sequences within a clinically feasible time of about 7 minutes.