Citations

With their unique therapeutic properties and amenability to engineering modifications, exosomes are considered a promising tool for treating peripheral nerve injuries. Through genetic engineering or physicochemical modifications, the targeting ability and functionality of exosomes can be further enhanced, enabling efficient delivery of therapeutic molecules and significantly boosting their therapeutic potential. This review aims to explore exosome-based therapies in peripheral nerve repair and their mechanisms and summarizes recent advances in the roles of exosomes in neuroprotection, axonal regeneration, vascular regeneration, and inflammatory modulation. Exosomes act as natural messengers between cells, carrying genetic materials, cytokines, and growth factors that can modulate the local microenvironment and foster peripheral nerve regeneration. Studies have shown that exosomes derived from Schwann cells, macrophages, neurons, and mesenchymal stem cells can all promote axonal regeneration and modulate inflammatory responses through various mechanisms. Compared with cell therapy, exosome therapy offers greater stability and safety, with the ability to traverse biological barriers, presenting new possibilities for regenerative medicine and precision therapy. However, challenges such as the heterogeneity and complexity of exosomes, uncertainty of in vivo distribution and metabolic pathways, and the limitations of targeting remain to be addressed. Future research will focus on the engineering modifications of exosomes to enhance their therapeutic efficiency and targeting precision.

Hippocampal segmentation is essential in neuroimaging for evaluating conditions like Alzheimer’s dementia and mesial temporal sclerosis, where small volume changes can significantly impact normative percentiles. However, inaccurate segmentation is common due to the inclusion of non-hippocampal structures such as choroid plexus and cerebrospinal fluid (CSF), leading to volumetric overestimation and confounding of functional analyses. Current methods of assessment largely rely on virtual or manual ground truth labels, which can fail to capture these inaccuracies. To address this shortcoming, this study introduces a more direct voxel intensity-based method of segmentation assessment. Using paired precontrast and postcontrast T1-weighted MRIs, hippocampal segmentations were refined by adding marginal gray matter and removing marginal CSF and enhancement to determine a total required correction volume. Six segmentation algorithms—e2dhipseg, HippMapp3r, hippodeep, AssemblyNet, FastSurfer, and QuickNat—were implemented and compared. HippMapp3r and e2dhipseg, followed closely by hippodeep, exhibited the least total correction volumes, indicating superior accuracy. Dedicated hippocampal segmentation algorithms outperformed whole-brain methods.

The Quantitative Imaging Biomarkers Alliance Profile for dynamic susceptibility contrast (DSC) MRI and its longitudinal claims for the precision of a DSC MRI–derived quantitative imaging biomarker to assess the relative cerebral blood volume changes in gliomas are summarized.

The implementation of clinical 7T MRI presents both opportunities and challenges for advanced medical imaging. This tutorial provides practical considerations and experiences with 7T MRI in clinical settings. We first explore the history and evolution of MRI technology, highlighting the benefits of increased signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and susceptibility at 7T. Technical challenges such as increased susceptibility artifacts and RF inhomogeneity are also discussed, along with innovative adaptations. This review also discusses hardware and software considerations, including new parallel transmission head coils and advanced image processing techniques to optimize image quality. Safety considerations, such as managing tissue heating and susceptibility to artifacts, are also discussed. Additionally, clinical applications of 7T MRI are examined, focusing on neurological conditions such as epilepsy, multiple sclerosis, and vascular imaging. Emerging trends in the use of 7T MRI for spectroscopy, perfusion imaging, and multinuclear imaging are explored, with insights into the future of ultra-high-field MRI in clinical practice. This review aims to provide clinicians, technologists, and researchers with a roadmap for successfully implementing 7T MRI in both research and clinical environments.