Magnetic resonance imaging
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The osteochondral junction (OCJ) of the knee joint is comprised of multiple tissue components, including a portion of the deep layer cartilage, calcified cartilage, and subchondral bone. The OCJ is of increasing radiological interest as it may be relevant in the early pathogenesis of osteoarthritis (OA). Due to its short transverse relaxation, the OCJ is invisible to clinical MR sequences. ⋯ Representative T1-weighted FS-UTE-Cones images of the whole knee of a healthy volunteer showed high signal intensity bands in the OCJ regions of the patella, femur, and tibia. On the other hand, T1-weighted FS-UTE-Cones imaging of the knee joints of OA patients revealed regions with reduction or loss of these high signal intensity bands in the OCJ regions, indicating abnormal OCJ tissue composition. The proposed 3D T1-weighted FS-UTE-Cones sequence with a 3-min scan time may be very useful for demonstrating the involvement of the OCJ regions in early OA.
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Arterial spin labeling MRI can quantify the cerebral blood flow (CBF) without exogenous tracer. However, the variation of arterial transit time across different brain regions introduces bias for measuring local CBF, especially for those subjects with long arterial transit time (ATT). Long post-labeling delay (PLD) or multi-PLD methods could mitigate the problem of heterogenous ATT at the expense of the signal-to-noise ratio (SNR). Long-label ASL might address the low SNR problem by increasing the amount of labeled arterial blood. Thus, we hypothesized that with the same relatively long PLD, long-label pCASL may be more robust and reproducible than standard-label pCASL in population with potentially prolonged ATT. The purpose of the study was to investigate the reliability and reproducibility of long-label pCASL in the whole brain and vascular regions of interest in an elderly population, compared with standard-label pCASL. ⋯ The study demonstrated good reliability and reproducibility of long-label pCASL in anterior brain regions in the elderly population. To further improve CBF quantification in a long-ATT population while proper PLD is already used, increasing the label duration may help.
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To develop a fast and accurate convolutional neural network based method for segmentation of thalamic nuclei. ⋯ The proposed segmentation method is fast, accurate, performs well across disease types and field strengths, and shows great potential for improving our understanding of thalamic nuclei involvement in neurological diseases.
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Robust voxelwise analysis using tract-based spatial statistics (TBSS) together with permutation statistical method is standardly used in analyzing diffusion tensor imaging (DTI) of brain. A similar analytical method could be useful when studying DTI of cervical spinal cord. Based on anatomical data of sixty-four healthy volunteers, white (WM) and gray matter (GM) masks were created and subsequently registered into DTI space. ⋯ Furthermore, using voxelwise analysis such WM voxels were identified where fraction anisotropy values differ depending on age (p < .05) and in these voxels linear dependence of fraction anisotropy and age (r = -0.57, p < .001) was confirmed by regression analysis. This dependence was not proven when using WM anatomical masks (r = -0.21, p = .10). The analytical approach presented shown to be useful for group analysis of DTI data for cervical spinal cord.