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Abstract #3093

in vivo Measurement of Axonal Diameter and Density of Human Corpus Callosum Using Bi-Gaussian Model Q-Planar MRI

Jun-Cheng Weng1, 2, Sih-Yu Lin1, Wen-Yih Isaac Tseng3, 4

1School of Medical Imaging and Radiological Sciences, Chung Shan Medical University, Taichung, Taiwan; 2Department of Medical Imaging, Chung Shan Medical University Hospital, Taichung, Taiwan; 3Center for Optoelectronic Biomedicine, National Taiwan University College of Medicine, Taipei, Taiwan; 4Department of Medical Imaging, National Taiwan University Hospital, Taipei, Taiwan

It is known that water signal decay in a MR diffusion experiment in neuronal tissues, at sufficiently high diffusion weighting, appears to be non-mono-exponential, thus complicating even further the interpretation and assignment of the different components to actual physiological compartments. Therefore, we used 2D bi-Gaussian model (i.e. slow and fast components) to fit our QPI data. After 2D Fourier transformation of the slow and fast Gaussian curved surfaces of signal decay, respectively, two Gaussian curved surfaces of displacement distribution (i.e. narrow and broad components) were obtained. Intracellular and extracellular information could then be extracted from the narrow and broad Gaussian displacement distributions, respectively. Our results demonstrated that bi-Gaussian fitting QPI produced reasonable distribution of relative axonal diameters of CC in normal human brain.