Publications by authors named "Remi Chaix"

Methods for the automated segmentation of brain structures are a major subject of medical research. The small structures of the deep brain have received scant attention, notably for lack of manual delineations by medical experts. In this study, we assessed an automated segmentation of a novel clinical dataset containing White Matter Attenuated Inversion-Recovery (WAIR) MRI images and five manually segmented structures (substantia nigra (SN), subthalamic nucleus (STN), red nucleus (RN), mammillary body (MB) and mammillothalamic fascicle (MT-fa)) in 53 patients with severe Parkinson's disease.

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Article Synopsis
  • Understanding the deep brain's architecture is difficult due to its complex structure, which controls movement and behavior, and lacks dedicated exploration tools.
  • A new deep-brain MRI architecture atlas was created using advanced MRI-based mapping techniques, featuring a young male adult template and various MRI datasets.
  • This open-source tool includes high-resolution images of 118 labeled deep brain structures, enhancing existing 3D atlases and clinical resources for better analysis.
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Background And Objective: The common structural interpretation of diffusion color-encoded (DCE) maps assumes that the brain is aligned with the gradients of the MRI machine. This is seldom achieved in the field, leading to incorrect red (R), green (G) and blue (B) DCE values for the expected orientation of fiber bundles. We studied the virtual reorientation of gradients according to the anterior commissure - posterior commissure (ACPC) system on the RGB derivatives.

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Article Synopsis
  • Subthalamic nucleus deep brain stimulation can improve motor symptoms in Parkinson's disease but may lead to speech and gait issues due to contact balance in electrode positioning.
  • A study involving 92 patients analyzed the effects of symmetric versus asymmetric electrode contact balance on speech and axial signs after one year of treatment.
  • Results indicate that symmetric settings significantly worsen speech and gait, suggesting a need to avoid such configurations to enhance patient outcomes.
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(1) Background: Glioblastoma multiforme (GBM) shows complex mechanisms of spreading of the tumor cells, up to remote areas, and little is still known of these mechanisms, thus we focused on MRI abnormalities observable in the tumor and the brain adjacent to the lesion, up to the contralateral hemisphere, with a special interest on tensor diffusion imaging informing on white matter architecture; (2) Material and Methods: volumes, macroscopic volume (MV), brain-adjacent-tumor (BAT) volume and abnormal color-coded DTI volume (aCCV), and region-of-interest samples (probe volumes, ipsi, and contra lateral to the lesion), with their MRI characteristics, apparent diffusion coefficient (ADC), fractional anisotropy (FA) values, and number of fibers (DTI fiber tracking) were analyzed in patients suffering GBM ( = 15) and metastasis ( = 9), and healthy subjects ( = 15), using ad hoc statistical methods (type I error = 5%) (3) Results: GBM volumes were larger than metastasis volumes, aCCV being larger in GBM and BAT ADC was higher in metastasis, ADC decreased centripetally in metastasis, FA increased centripetally either in GBM or metastasis, MV and BAT FA values were higher in GBM, ipsi FA values of GBM ROIs were higher than those of metastasis, and the GBM ipsi number of fibers was higher than the GBM contra number of fibers; (4) Conclusions: The MV, BAT and especially the aCCV, as well as their related water diffusion characteristics, could be useful biomarkers in oncology and functional oncology.

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Risk-taking behaviors of adult bedridden patients in neurosurgery are frequent, however little analyzed. We aimed to estimate from the literature and our clinical experience the incidence of the different clinical pictures. Risk-taking behaviors seem to be more frequent than reported.

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Mastering detailed anatomy of the human deep brain in clinical neurosciences is challenging. Although numerous pioneering works have gathered a large dataset of structural and topographic information, it is still difficult to transfer this knowledge into practice, even with advanced magnetic resonance imaging techniques. Thus, classical histological atlases continue to be used to identify structures for stereotactic targeting in functional neurosurgery.

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Flow-diverting stents (FD) are admitted therapeutic devices for challenging aneurysms. Delayed migrations of FD remain exceptional, particularly with brainstem compression. We report a case of delayed migration of pipeline embolization device (PED) responsible of medulla oblongata compression due to expansion of posterior inferior cerebellar artery (PICA) aneurysm.

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Syringomyelia is an abnormal cystic dilatation of the spinal cord caused by excessive accumulation of CSF (cerebrospinal fluid). The pathophysiology remains complex and unelucidated. We report a rare case of resolution of cervico-thoracic syringomyelia after thoracic disc excision in a 3 months follow-up time.

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