MRI evaluation of regional and longitudinal changes in Z‐spectra of injured spinal cord of monkeys

Abstract

Characterization of multiple proton pools from Z-spectra permitted noninvasive, regional, quantitative assessments of changes in tissue composition of injured spinal cord over time. Magn Reson Med 79:1070-1082, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Differentiation of Myositis-Induced Models of Bacterial Infection and Inflammation with T2-Weighted, CEST, and DCE-MRI

“…The T 2 -weighted MRI signals of the ROIs (Figure 1C) were higher for both the infected and inflamed tissues (tissue classes 0 and 2 in Figures 1 and 2) than for the normal tissues that appeared almost identical (tissue classes 1 and 3 in Figures 1 and 2). The CEST spectra of the tissue ROIs showed a significant decrease in water signal between −1.5 and −4 ppm owing to the relayed nuclear overhauser effect of aliphatic protons on proteins and lipids (Figure 1B; 38, 39). The DCE-MRI %SNR (signal-to-noise ratio) evolutions showed a clear difference between the infected and inflamed tissues from normal tissue (Figure 1D).…”

Longitudinal changes in DTI parameters of specific spinal white matter tracts correlate with behavior following spinal cord injury in monkeys

“…We also examined white matter changes at the injury site and surrounding spinal segments. We have shown previously that spinal tissues at the center of injury undergo dynamic changes in cell density and accumulations of liquid if a cyst is formed 29 . Again, here we showed that FA, MD, and RD values are also sensitive measures for evaluating the degree and spatial extent of the damaged spinal cord tissue at the injury center (Fig.…”

Spatiotemporal trajectories of quantitative magnetization transfer measurements in injured spinal cord using simplified acquisitions

“…1C). Only regions with homogeneous B 0 and B 1 (|ΔB 0 | < 100 Hz, and |ΔB 1ratio | < 0.05) were selected and included in the ROI analysis (<1.5 cm in length) (Wang et al, 2018a, Wang et al, 2018b). To minimize partial volume effects, small ROIs were selected and voxels residing along the SC – CSF border were excluded.…”

“…Injury may induce cell death, and lead to demyelination (Guest et al, 2005; Totoiu and Keirstead, 2005), edema and formation of cysts (Thuret et al, 2006) in the cord tissues over time. Non-invasive quantitative magnetic resonance imaging (MRI) methods are well suited for monitoring the damage to, and recovery of, injured spinal cord tissues, and can provide comprehensive information on structural, functional and molecular changes (Stroman et al, 2014; Wheeler-Kingshott et al, 2014; Chen et al, 2015; Wang et al, 2015; Yang et al, 2015; Wang et al, 2016; Wang et al, 2018a, Wang et al, 2018b). To fully characterize the underlying spontaneous recovery of damaged cords, it is possible to monitor changes in multiple MRI parameters at and around spinal cord lesion sites and ultimately relate these non-invasive MRI measures to the behavioral recovery in monkeys with SCI (Chen et al, 2015; Wang et al, 2015; Wang et al, 2016; Wang et al, 2018a, Wang et al, 2018b).…”

“…Measurements of the magnetization transfer ratio (MTR) (Wolff and Balaban, 1989) have been used to assess changes in macromolecular composition in neurological disorders (Catalaa et al, 2000; Odrobina et al, 2005), renal disease (Wang et al, 2014), cancer (Quesson et al, 1997), and SCI (Ng et al, 2009; Wang et al, 2015). However, the sensitivity, specificity and reproducibility of MTR measures can be influenced by various experimental parameters such as MT saturation power and RF offset (McGowan 3rd et al, 1994; Ramani et al, 2002; Wang et al, 2018a, Wang et al, 2018b). Moreover, MTR measures tend to reflect a complex combination of exchange and relaxation parameters (Eng et al, 1991; McGowan 3rd et al, 1994), so the interpretation of MTR changes is not always clear.…”