32 research outputs found

    MRI evaluation of tissue iron burden in patients with β-thalassaemia major

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    β-Thalassaemia major is a hereditary haemolytic anaemia that is treated with multiple blood transfusions. A major complication of this treatment is iron overload, which leads to cell death and organ dysfunction. Chelation therapy, used for iron elimination, requires effective monitoring of the body burden of iron, for which serum ferritin levels and liver iron content measured in liver biopsies are used as markers, but are not reliable. MRI based on iron-induced T2 relaxation enhancement can be used for the evaluation of tissue siderosis. Various MR protocols using signal intensity ratio and mainstream relaxometry methods have been used, sometimes with discrepant results. Relaxometry methods using multiple echoes achieve better sampling of the time domain in which relaxation mechanisms take place and lead to more precise results. In several studies the MRI parameters of liver siderosis have failed to correlate with those of other affected organs, underlining the necessity for MRI iron evaluation in individual organs. Most studies have included children in the evaluated population, but MRI data on very young children are lacking. Wider application of relaxometry methods is indicated, with the establishment of universally accepted MRI protocols, and further studies, including young children, are needed

    The role of ventral tegmental area in chronic stroke rehabilitation: an exploratory study

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    Introduction: The acknowledged role of external rewards in chronic stroke rehabilitation, offering positive reinforcement and motivation, has significantly contributed to patient engagement and perseverance. However, the exploration of self-reward’s importance in this context remains limited. This study aims to investigate the functional connectivity of the ventral tegmental area (VTA), a key node in the brain’s reward circuitry, during motor task-based rehabilitation and its correlation with the recovery process. Methods: Twelve right-handed healthy volunteers (4 men, 8 women, aged 57.4 ± 11.3 years) and twelve chronic stroke patients (5 men, 7 women, aged 48.1 ± 11.1 years) with clinically significant right-sided motor impairment (mean FM-UE score of 27.6 ± 8.7) participated. The analysis employed the CONN toolbox to assess the association between motor tasks and VTA connectivity using psychophysiological interaction (PPI). Results: PPI analysis revealed motor-dependent changes in VTA connectivity, particularly with regions within the motor circuitry, cerebellum, and prefrontal cortex. Notably, stronger connectivity between the ipsilesional VTA and cerebellum was observed in healthy controls compared to chronic stroke patients, highlighting the importance of VTA-cerebellum interactions in motor function. Stroke patients’ motor performance was associated with VTA modulation in areas related to both motor tasks and reward processing, emphasizing the role of self-reward processes in rehabilitation. Changes in VTA influence on motor circuitry were linked to improvements in motor performance resulting from rehabilitation. Discussion: Our findings underscore the potential of neuroimaging techniques in quantifying and predicting rehabilitation outcomes by examining self-reward processes. The observed associations between VTA connectivity and motor performance in both healthy and stroke-affected individuals emphasize the role of psychological factors, particularly self-reward, in the rehabilitation process. This study contributes valuable insights into the intricate interplay between reward circuits and motor function, highlighting the importance of addressing psychological dimensions in neurorehabilitation strategies

    Functional MRI of Rehabilitation in Chronic Stroke Patients Using Novel MR-Compatible Hand Robots

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    We monitored brain activation after chronic stroke by combining functional magnetic resonance imaging (fMRI) with a novel MR-compatible, hand-induced, robotic device (MR_CHIROD). We evaluated 60 fMRI datasets on a 3 T MR system from five right-handed patients with left-sided stroke ≥6 months prior and mild to moderate hemiparesis. Patients trained the paretic right hand at approximately 75% of maximum strength with an exercise ball for 1 hour/day, 3 days/week for 4 weeks. Multi-level fMRI data were acquired before, during training, upon completion of training, and after a non-training period using parallel imaging employing GeneRalized Autocalibrating Partially Parallel Acquisitions (GRAPPA) while the participant used the MR_CHIROD. Training increased the number of activated sensorimotor cortical voxels, indicating functional cortical plasticity in chronic stroke patients. The effect persisted four weeks after training completion, indicating the potential of rehabilitation in inducing cortical plasticity in chronic stroke patients
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