No abstract

White matter bundle segmentation using diffusion MRI fiber tractography has become the method of choice to identify white matter fiber pathways in vivo in human brains. However, like other analyses of complex data, there is considerable variability in segmentation protocols and techniques. This can result in different reconstructions of the same intended white matter pathways, which directly affects tractography results, quantification, and interpretation. In this study, we aim to evaluate and quantify the variability that arises from different protocols for bundle segmentation. Through an open call to users of fiber tractography, including anatomists, clinicians, and algorithm developers, 42 independent teams were given processed sets of human wholebrain streamlines and asked to segment 14 white matter fascicles on six subjects. In total, we received 57 different bundle segmentation protocols, which enabled detailed volume-based and streamline-based analyses of agreement and disagreement among protocols for each fiber pathway. Results show that even when given the exact same sets of underlying streamlines, the variability across protocols for bundle segmentation is greater than all other sources of variability in the virtual dissection process, including variability within protocols and variability across subjects. In order to foster the use of tractography bundle dissection in routine clinical settings, and as a fundamental analytical tool, future endeavors must aim to resolve and reduce this heterogeneity. Although external validation is needed to verify the anatomical accuracy of bundle dissections, reducing heterogeneity is a step towards reproducible research and may be achieved through the use of standard nomenclature and definitions of white matter bundles and well-chosen constraints and decisions in the dissection process.

Background During the COVID-19 pandemic, telehealth technologies were used in the primary health care setting in New Brunswick as a means to continue providing care to patients while following public health guidelines. This study aimed to measure these changes and examine if they improved timely access to primary care. A secondary goal was to identify which telehealth technologies were deemed sustainable by primary care providers. Methods This was a comparative study on the use of telehealth technology before and during the COVID-19 pandemic. Between April 2020 and November 2020, 114 active primary care providers (family physicians or nurse practitioners) responded to the online survey. Results The findings illustrated an increase in the use of telehealth technologies. The use of phone consultations increased by 122%, from 43.9% pre-pandemic to 97.6% during the pandemic (p < 0.001). The use of virtual consultation (19.3% pre-pandemic vs. 41.2% during the pandemic, p < 0.001), emails and texts also increased during the pandemic. Whereas the more structural organizational tools (electronic medical charts and reservation systems) remained stable. However, those changes did not coincide with a significant improvement to timely access to care during the pandemic. Many participants (40.1%) wanted to keep phone consultations, and 21.9% of participants wanted to keep virtual consultations as part of their long-term practice. Interpretation The observed increase in the use of telehealth technologies may be sustainable, but it has not significantly improved timely access to primary care in New Brunswick.

Structural and functional magnetic resonance imaging (MRI) studies have suggested a neuroanatomical basis that may underly attention-deficit–hyperactivity disorder (ADHD), but the anatomical ground truth remains unknown. In addition, the role of the white matter (WM) microstructure related to attention and impulsivity in a general pediatric population is still not well understood. Using a state-of-the-art structural connectivity pipeline based on the Brainnetome atlas extracting WM connections and its subsections, we applied dimensionality reduction techniques to obtain biologically interpretable WM measures. We selected the top 10 connections-of-interests (located in frontal, parietal, occipital, and basal ganglia regions) with robust anatomical and statistical criteria. We correlated WM measures with psychometric test metrics (Conner’s Continuous Performance Test 3) in 171 children (27 Dx ADHD, 3Dx ASD, 9–13 years old) from the population-based GESTation and Environment cohort. We found that children with lower microstructural complexity and lower axonal density show a higher impulsive behavior on these connections. When segmenting each connection in subsections, we report WM alterations localized in one or both endpoints reflecting a specific localization of WM alterations along each connection. These results provide new insight in understanding the neurophysiology of attention and impulsivity in a general population.

The segmentation of brain structures is a key component of many neuroimaging studies. Consistent anatomical definitions are crucial to ensure consensus on the position and shape of brain structures, but segmentations are prone to variation in their interpretation and execution. White-matter (WM) pathways are global structures of the brain defined by local landmarks, which leads to anatomical definitions being difficult