Journal of neuroimaging : official journal of the American Society of Neuroimaging
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Diffusion tensor imaging (DTI) tractography reconstruction of white matter pathways can help guide brain tumor resection. However, DTI tracts are complex mathematical objects and the validity of tractography-derived information in clinical settings has yet to be fully established. To address this issue, we initiated the DTI Challenge, an international working group of clinicians and scientists whose goal was to provide standardized evaluation of tractography methods for neurosurgery. The purpose of this empirical study was to evaluate different tractography techniques in the first DTI Challenge workshop. ⋯ The DTI Challenge provides a benchmark for the standardized evaluation of tractography methods on neurosurgical data. This study suggests that there are still limitations to the clinical use of tractography for neurosurgical decision making.
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Meta Analysis
A Meta-Analysis of fMRI Activation Differences during Episodic Memory in Alzheimer's Disease and Mild Cognitive Impairment.
Functional MRI (fMRI) has the potential to be used as a tool to detect biomarkers related to classifying Alzheimer's disease (AD) and its prodromal stage, mild cognitive impairment (MCI). Previous meta-analyses suggest that during episodic memory tasks, MCI patients exhibit hyperactivation in the medial temporal lobe (MTL) while AD patients exhibit hypoactivation, compared to healthy older adults (HOAs). However, these previous studies have methodological weaknesses that limit the generalizability of the results. ⋯ Additionally, the HOA sample showed more activation in the right hippocampus compared to the AD sample. The MCI studies showed greater activation in the cerebellum compared to the HOA sample, potentially indicating a compensatory mechanism for verbal encoding. MTL hypoactivation in the AD sample is consistent with previous studies, but more evidence of MCI hyperactivation is needed before considering MTL activation as an early biomarker for the AD disease process.
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We sought to identify MRI factors associated with BBB changes at the acute stage of ischemic stroke. ⋯ BBB changes are exceptional during the first 3 hours after stroke onset. Delayed BBB alteration was associated with FLAIR positivity mainly reflecting vasogenic edema.
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To characterize relations between configurations of the posterior part of the Circle of Willis (CoW) and the occurrence of unilateral thalamic infarction. ⋯ Assessment of CoW configuration on MRA may be helpful to understand the appearance of unilateral thalamic stroke independent from stroke etiology. A smaller diameter of the relevant CoW segment might be a risk factor for ipsilateral thalamic stroke in the corresponding thalamic vascular territory.
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Pontine tegmental cap dysplasia (PTCD) is recently recognized as a rare congenital brain stem malformation with typical neuroimaging hallmarks of ventral pontine hypoplasia and vaulted pontine tegmentum projecting into the fourth ventricle. PTCD patients also demonstrate variable cranial neuropathy with predilection for involvement of the vestibulocochlear and facial nerves. ⋯ During early infancy, the patient displayed features of multiple cranial neuropathies and bilateral hearing loss. At the age of 2, the patient underwent further MRI assessment with dedicated high resolution T2 SPACE sequence to delineate the cranial nerve deficiencies.