Microscope-based augmented reality with diffusion tensor imaging and fluorescein in insular glioma resection

Maximal safe resection is the goal of insular glioma surgery. The combination of intraoperative augmented reality (AR) diffusion tensor imaging (DTI) fiber tracking with fluorescein dye (F) helps achieve this goal throughout a microscope-based visualization of the tumor and white matter fiber tracts. The aim of the present video article was to show the technical key aspects of DTI-F microscope-based AR-assisted surgery during the gross-total resection of an insular Berger-Sanai type I+IV high-grade glioma in a 63-year-old patient, performed through a pterional transsylvian approach. The video can be found here: https://stream.cadmore.media/r10.3171/2021.10.FOCVID2157

Mapping covariance in brain FDG uptake to structural connectivity

Purpose Inter-subject covariance of regional 18F-fluorodeoxyglucose (FDG) PET measures (FDGcov) as proxy of brain connectivity has been gaining an increasing acceptance in the community. Yet, it is still unclear to what extent FDGcov is underlied by actual structural connectivity via white matter fiber tracts. In this study, we quantified the degree of spatial overlap between FDGcov and structural connectivity networks. Methods We retrospectively analyzed neuroimaging data from 303 subjects, both patients with suspected neurodegenerative disorders and healthy individuals. For each subject, structural magnetic resonance, diffusion tensor imaging, and FDG-PET data were available. The images were spatially normalized to a standard space and segmented into 62 anatomical regions using a probabilistic atlas. Sparse inverse covariance estimation was employed to estimate FDGcov. Structural connectivity was measured by streamline tractography through fiber assignment by continuous tracking. Results For the whole brain, 55% of detected connections were found to be convergent, i.e., present in both FDGcov and structural networks. This metric for random networks was significantly lower, i.e., 12%. Convergent were 80% of intralobe connections and only 30% of interhemispheric interlobe connections. Conclusion Structural connectivity via white matter fiber tracts is a relevant substrate of FDGcov, underlying around a half of connections at the whole brain level. Short-range white matter tracts appear to be a major substrate of intralobe FDGcov connections.

Micro structural abnormalities of the Cingulum in children with focal epilepsy: DTI study

Aim of the work The aim of this study is to evaluate the microstructural alteration implicating the Cingulum (CG) as one of the major limbic system white matter fiber tracts; in children with focal epilepsy. Patients and methods Our study was carried out on twenty-one children with the clinical and EEG diagnosis of focal epilepsy and 22 control subjects who were age and sex matched to patient group in the study. All patients underwent an epilepsy specific MRI protocol. DTI and fiber tractography was performed to all subjects as well. Fractional anisotropy (FA), axial diffusivity, radial diffusivity (RD) and trace were calculated for CG. DTI metrics were compared between both hemispheres as well as between both groups patient group and control group. A p-value less than .05 was considered significant. Results Asymmetry in FA, RD, trace and AD values of the CG was demonstrated in patients with focal epilepsy between both hemispheres with significantly lower FA and higher diffusivity values reaching p < 0.001in CG in both hemispheres in patients with focal epilepsy when compared together regardless the seizure focus. Compared with controls, patients with left focal epilepsy demonstrated significant lower FA and higher diffusivity indices in both ipsilateral and contralateral fiber tracts as well p < 0.05. Patients with right focal epilepsy showed no significant asymmetry in different DTI metrics when compared to controls. Conclusion Reduction in FA values along with increased diffusivity measures in the CG reflects the microstructural changes taking place in children with focal epilepsy.

Listeria Monocytogenes Brain Abscesses in a Patient with Disseminated Non-Small Cellular Lung Cancer: MRI Findings

Brain abscesses caused by Listeria monocytogenes (LM) are very rare and carry a high mortality risk. We present a patient with disseminated non-small cellular lung cancer (NSCLC) and multiple unusual LM brain abscesses. These abscesses have multiple elongated peripherally enhancing lesions in a characteristic formation that is “worm or tramtrack-like” following the white matter fiber tracts.

Relevant Biophysical Parameters Discrimination along Corticospinal Tract in Patients with Stroke Using Convolutional Neural Networks

Stroke remains the leading source of long-term disability. As the only direct descending motor pathway, the corticospinal tract (CST) is the primary pathway to innervate spinal motor neurons and one of the most well studied tracts in human neuroanatomy. Its clinical significance can be demonstrated in many distinguished traumatic situations and diseases such as stroke. Along‐tract statistics analysis enables the extraction of quantitative diffusion metrics along specific white matter fiber tracts. Besides quantitative metrics derived from classical diffusion tensor imaging (DTI), such as fractional anisotropy and diffusivities. In this study, we extracted DTI derived quantitative microstructural diffusion metrics along the CST tract in patients with moderate to severe subacute stroke. Respectively DTI metric of individual patient's fiber tract was then plotted. This approach may be useful for future studies that may compare in two different time (acute and chronic). The contribution of this work presents a totally computerized method of DTI image recognition based on conventional neural network (CNN) in order to supply quantitative appraisal of clinical characteristics. The obtained results have achieved an important classification (Accuracy=94.12%) when applying the CNN. The proposed methodology enables us to assess the classification of the used DTI images database within a reduced processing time. Experimental results prove the success of the proposed rating system for a suitable analysis of microstructural diffusion when compared to previous work.

Enhanced White Matter Fiber Tracts in Advanced Jazz Improvisers

Human cognition and behavior arise from neuronal interactions over brain structural networks. These neuronal interactions cause changes in structural networks over time. How a creative activity such as musical improvisation performance changes the brain structure is largely unknown. In this diffusion magnetic resonance imaging study, we examined the brain’s white matter fiber properties in previously identified functional networks and compared the findings between advanced jazz improvisers and non-musicians. We found that, for advanced improvisers compared with non-musicians, the normalized quantitative anisotropy (NQA) is elevated in the lateral prefrontal areas and supplementary motor area, and the underlying white matter fiber tracts connecting these areas. This enhancement of the diffusion anisotropy along the fiber pathway connecting the lateral prefrontal and supplementary motor is consistent with the functional networks during musical improvisation tasks performed by expert jazz improvisers. These findings together suggest that experts’ creative skill is associated with the task-relevant, long-timescale brain structural network changes, in support of related cognitive underpinnings.