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Inhaled hyperpolarized 129 Xe MRI is a non-invasive and radiation risk free lung imaging method, which can directly measure the business unit of the lung where gas exchange occurs: the alveoli and acinar ducts (lung function). Currently, three imaging approaches have been demonstrated to be useful for hyperpolarized 129 Xe MR in lungs: Fast Gradient Recalled Echo (FGRE), Radial Projection Reconstruction (PR), and spiral/cones. Typically, non-Cartesian acquisitions such as PR and spiral/cones require specific data post-processing, such as interpolating, regridding, and density-weighting procedures for image reconstruction, which often leads to smoothing effects and resolution degradation. On the other hand, Cartesian methods such as FGRE are not short-echo time (TE) methods; they suffer from imaging gradient-induced diffusion-weighting of the k-space center, and employ a significant number of radio-frequency (RF) pulses. Due to the non-renewable magnetization of the hyperpolarized media, the use of a large number of RF pulses (FGRE/PR) required for full k-space coverage is a significant limitation, especially for low field (<0.5 T) hyperpolarized gas MRI. We demonstrate an ultra-fast, purely frequency-encoded, Cartesian pulse sequence called Frequency-Encoding Sectoral (FES), which takes advantage of the long T 2 * of hyperpolarized 129 Xe gas at low field strength (0.074 T). In contrast to PR/FGRE, it uses a much smaller number of RF pulses, and consequently maximizes image Signal-to-Noise Ratio (SNR) while shortening acquisition time. Additionally, FES does not suffer from non-uniform T 2 * decay leading to image blurring; a common issue with interleaved spirals/cones. The Cartesian k-space coverage of the proposed FES method does not require specific k-space data post-processing, unlike PR/FGRE and spiral/cones methods. Proton scans were used to compare the FES sequence to both FGRE and Phase Encoding Sectoral, in terms of their SNR values and imaging efficiency estimates. Using FES, proton and hyperpolarized 129 Xe images were acquired from a custom hollow acrylic phantom (0.04L) and two normal rats ( 129 Xe only), utilizing both single-breath and multiple-breath schemes. For the 129 Xe phantom images, the apparent diffusion coefficient, T 1 , and T 2 * relaxation maps were acquired and generated. Blurring due to the T 2 * decay and B 0 field variation were simulated to estimate dependence of the image resolution on the duration of the data acquisition windows (i.e. sector length), and temperature-induced resonance frequency shift from the low field magnet hardware., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Crown Copyright © 2022. Published by Elsevier Inc. All rights reserved.)

Objectives: Composition of saliva reflects the condition of the oral cavity., The Aim of the Study: Investigation of the concentrations of MMP-1 (Matrix metalloproteinase-1), MMP-2 (Matrix metalloproteinase-2) and fibronectin in the saliva of patients planned for endodontic treatment or surgical extraction., Material and Methods: Seventy-five patients with caries and 14 healthy subjects were included in the study. Subjects were divided into group 1, in which 50 patients were planned for endodontic treatment, and group 2, in which 25 patients were planned for surgical extraction. For the measurements, we used a surface plasmon resonance imaging biosensor., Results: We found higher levels of MMP-1, MMP-2 and fibronectin in the saliva of patients planned for dental treatment than in healthy donors. We found lower concentrations of MMP-2 in subjects planned for surgical extraction, than in patients planned for endodontic treatment; however, there were no such differences in salivary concentrations of MMP-1 and fibronectin. There were no statistically significant differences in MMP-1 concentrations in the saliva before and after any type of dental treatment, but contrary to that, we found a statistically significant decrease in MMP-2 concentrations after endodontic treatment and after surgical extraction. We found a significant rise in the concentrations of fibronectin after surgical extraction but not after endodontic treatment., Conclusions: The concentrations of MMP-1 and MMP-2 in the saliva of our patients with caries were increased in comparison to healthy individuals, but after the treatment-so sanation of the oral cavity-we noted a decrease in matrix metalloproteinases (MMPs) levels. MMPs can be found in gingival crevicular fluid and saliva, carious dentin and plaque. According to our observations, the main source of MMPs in patients with caries is probably carious dentin. Increase in the salivary levels of fibronectin (FN) after surgical extraction may be connected with soft tissue injury caused by surgical extraction. Our results are another example of the fact that higher salivary concentrations of MMP-1, MMP-2 and FN can reflect the health status of the oral cavity in patients with caries.

Transcranial direct current stimulation (tDCS) is a form of non-invasive brain stimulation that may modulate cortical excitability, metabolite concentration, and human behaviour. The supplementary motor area (SMA) has been largely ignored as a potential target for tDCS neurorehabilitation but is an important region in motor compensation after brain injury with strong efferent connections to the primary motor cortex (M1). The objective of this work was to measure tissue metabolite changes in the human motor cortex immediately following tDCS. We hypothesized that bihemispheric tDCS would change levels of metabolites involved in neuromodulation including N-acetylaspartate (NAA), glutamate (Glu), and creatine (tCr). In this single-blind, randomized, cross-over study, fifteen healthy adults aged 21-60 participated in two 7T MRI sessions, to identify changes in metabolite concentrations by magnetic resonance spectroscopy. Immediately after 20 minutes of tDCS, there were no significant changes in metabolite levels or metabolite ratios comparing tDCS to sham. However there was a trend toward increased NAA/tCr concentration (p = 0.08) in M1 under the stimulating cathode. There was a strong, positive correlation between the change in the absolute concentration of NAA and the change in the absolute concentration of tCr (p<0.001) suggesting an effect of tDCS. Both NAA and creatine are important markers of neurometabolism. Our findings provide novel insight into the modulation of neural metabolites in the motor cortex immediately following application of bihemispheric tDCS., Competing Interests: The authors have declared that no competing interests exist.