Displacement imaging of spinal cord using q‐space diffusion‐weighted MRI

Abstract

Displacement MR images of water in in vitro rat spinal cord were computed from q-space analysis of high b value diffusion-weighted MRI data. It is demonstrated that q-space analysis of heavily diffusion-weighted MRI (qs-DWI) provides MR images in which physical parameters of the tissues such as the mean displacement and the probability for zero displacement of the water molecules are used as contrasts. It is shown that these MR images provide structural information surpassing the spatial resolution of conventional MRI by several orders of magnitude. This imaging methodology was used to follow spinal cord maturation in the rat. It was found that changes in the diffusion characteristics of white matter upon maturation are responsible for the emergence of gray/white matter contrast. The mean displacement of water molecules in the white and gray matter of the mature rat spinal cord was found to be 2-3, and 8-10 microns, respectively. The potential and the limitations of this new imaging methodology for early detection of white matter disorders are discussed. Magn Reson Med 44:713-722, 2000.

Effects of restricted diffusion in a biological phantom: a q-space diffusion MRI study of asparagus stems at a 3T clinical scanner

“…It is thereby possible to characterise complex systems, for example, situations where the diffusion is restricted to confinements. In nuclear magnetic resonance (NMR), q-space analysis is widely used to study porous media [13] and q-space imaging in a clinical setting was first introduced by Assaf et al [14]. The q-space technique might be valuable for studies of brain pathologies, including ischemic stroke, neurodegenerative diseases like various forms of dementia [15] and Parkinson's disease as well as white matter degeneration like in multiple sclerosis (MS) [16].…”

The effect of experimental parameters on the signal decay in double-PGSE experiments: Negative diffractions and enhancement of structural information

“…This study also showed that the structural information obtained from the diffusion-diffraction dips and from the PDF obtained by the Fourier transform (FT) of the signal decay, were the same [21]. This is important since q-space diffusion MR, which had been used to study red blood cells [22,23] has recently been used to study neuronal tissue and WM in the central nervous system, both in vitro and in vivo [24][25][26][27][28][29][30][31][32]. In these cases, diffractions were not observed, probably due to the distribution of axon sizes [18,27,33].…”

The effect of the rotational angle on MR diffusion indices in nerves: Is the rms displacement of the slow-diffusing component a good measure of fiber orientation?

“…Bar-Shir, Y. Cohen / Journal of Magnetic Resonance 190 (2008) [33][34][35][36][37][38][39][40][41][42] on the bulk ADC values obtained from low b-value diffusion NMR. Since diffraction patterns are generally not apparent in neuronal tissues [29][30][31][32][33]37], in contrast to what we found for uniform micro-cylinders [34], we focused on the rms displacement extracted from the FWHH of the displacement distribution profiles obtained. In addition, in a uniform micro-cylinders study [34], only a single Gaussian was needed to fit the data, whereas in the present study, bi-Gaussian functions were needed to fit the experimental data.…”

“…The q-space approach, originally developed by Callaghan [24] and by Cory and Garroway [25], was subsequently proposed as a means to obtain structural information from high b-value (high q) diffusion MR data in neuronal tissues [26][27][28][29][30][31]. This approach was extended to MRI and was first used to study structures and pathologies in isolated organs using strong gradient systems [29,32].…”

“…This approach was extended to MRI and was first used to study structures and pathologies in isolated organs using strong gradient systems [29,32]. Later, this approach was used on clinical MRI scanners to detect white matter associated disorders [30,33].…”