Magnetic resonance imaging
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Neurite Orientation Dispersion and Density Imaging (NODDI) has been gaining prominence for estimating multiple diffusion compartments from MRI data acquired in a clinically feasible time. To establish a pathway for adoption of NODDI in clinical studies, it is important to understand the sensitivity and reproducibility of NODDI metrics on empirical data in the context of acquisition protocol and brain anatomy. Previous studies addressed reproducibility across the 3 T scanners and within session and between subject reproducibility at 1.5 T and 3 T. ⋯ On the other hand, ODI is more sensitive to the number of gradient directions compared to b-value selection. Single-shell results for ODI are more comparable to 2-shell data at lower b-values than higher b-values. Recommended settings by region of interest and acquisition time are reported for the researchers considering using NODDI in human studies and/or comparing results across acquisition protocols.
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We present three-dimensional ultrashort echo time Cones (3D-UTE-Cones) imaging as well as quantification of T2* and magnetization transfer ratio (MTR) of Achilles tendon and its enthesis of healthy volunteers and patients with psoriatic arthritis (PsA) using a 3T scanner. Quantitative T2*, T2 and magnetization transfer ratio (MTR) measurements of Achilles tendon and its enthesis were performed on healthy volunteers (n=7) and PsA patients (n=9) with 3D-UTE-Cones and clinical sequences at 3T. T2* was measured via single-component fitting of UTE images from two interleaved dual echo 3D-UTE-Cones acquisitions. ⋯ GRE-MTR values showed no significant differences between the groups. No reliable T2 measurement could be achieved with the CPMG sequence due to insufficient signal from entheses and tendons. The 3D-UTE-Cones sequences can be used for morphological and quantitative evaluation of entheses and tendons in PsA patients.
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While PRESS is often employed to measure glutamate concentrations, MEGA-PRESS enables simultaneous Glx (glutamate and glutamine) and GABA measurements. This study aimed to compare validation, repeatability, and concordance of different approaches for glutamate quantification at 3T to aid future studies in their selection of the appropriate sequence and quantification method. ⋯ Both PRESS and MEGA-PRESS can be employed to measure in vivo glutamate concentrations, although PRESS shows a better repeatability. Comparisons between in vivo glutamate measures of different sequences however need to be interpreted cautiously.
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To explore the diffusion and kurtosis features of cervical cancer (CC) and study the feasibility of diffusion kurtosis imaging (DKI) based on the non-Gaussian diffusion-weighted model to differentiate the stage and grade of CC. ⋯ The pilot study demonstrated that these diffusion and kurtosis indices from DKI based on the non-Gaussian diffusion-weighted model putatively differentiated the grade and stage of CC.
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Adequate evaluation of spinal cord parenchyma and accurate identification of injury range are considered two premises for the research and treatment of chronic spinal cord injury (SCI). Diffusion tensor imaging (DTI) provides information about water diffusion in spinal cord, and thus makes it possible to realize these premises. ⋯ DTI parameters might comprehensively reflect the post-SCI pathological status of spinal cord parenchyma at the epicenter and distal parts during the chronic stage, while showing good consistency with locomotor performance. DTI combined with tractography could intuitively display the distribution of spared fibers after SCI and accurately provide information such as cavity area. This may shed light on the research and treatment of chronic SCI.