Limb Preference Changes after Focused-Ultrasound Thalamotomy for Tremor.

Background: Magnetic resonance-guided focused-ultrasound (MRgFUS) thalamotomy is an effective treatment for essential and other tremors. It targets the ventrointermedius (Vim) nucleus, which is the thalamic relay in a proprioceptive pathway, and contains kinesthetic cells. Although MRgFUS thalamotomy reduces some risks associated with more invasive surgeries, it still has side effects, such as balance and gait disturbances; these may be caused by the lesion impacting proprioception.

Microstructural Abnormalities of the Dentatorubrothalamic Tract in Cervical Dystonia.

Background: The dentatorubrothalamic tract (DRTT) remains understudied in idiopathic cervical dystonia (CD), despite evidence that the pathway is relevant in the pathophysiology of the disorder.

Objective: The aim of this study was to examine the DRTT in patients with CD using diffusion tensor imaging (DTI)-based tractography.

Methods: Magnetic resonance imaging scans from 67 participants were collected to calculate diffusion tractography metrics using a binary tractography-based DRTT template.

Development of short-range white matter in healthy children and adolescents.

Neural communication is facilitated by intricate networks of white matter (WM) comprised of both long and short range connections. The maturation of long range WM connections has been extensively characterized, with projection, commissural, and association tracts showing unique trajectories with age. There, however, remains a limited understanding of age-related changes occurring within short range WM connections, or U-fibers.

Dynamic DTI (dDTI) shows differing temporal activation patterns in post-exercise skeletal muscles.

Object: To assess post-exercise recovery of human calf muscles using dynamic diffusion tensor imaging (dDTI).

Materials And Methods: DTI data (6 directions, b = 0 and 400 s/mm) were acquired every 35 s from seven healthy men using a 3T MRI, prior to (4 volumes) and immediately following exercise (13 volumes, ~7.5 min).

Safe MRI-Compatible electrical muscle stimulation (EMS) system.

Purpose: To develop an inexpensive magnetic resonance imaging (MRI)-compatible electrical muscle stimulation (EMS) unit and test it for safety and efficacy.

Materials And Methods: A simple MRI-compatible EMS device was developed using radiofrequency (RF) translucent electrodes at 3T. RF heating concerns were assessed using optical temperature measurements at electrode sites, during scanning of a phantom.

An exploration of diffusion tensor eigenvector variability within human calf muscles.

Purpose: To explore the effect of diffusion tensor imaging (DTI) acquisition parameters on principal and minor eigenvector stability within human lower leg skeletal muscles.

Materials And Methods: Lower leg muscles were evaluated in seven healthy subjects at 3T using an 8-channel transmit/receive coil. Diffusion-encoding was performed with nine signal averages (NSA) using 6, 15, and 25 directions (NDD).

Tumor volumetric measurements in surgically inaccessible pediatric low-grade glioma.

Tumor measurement is important in unresectable pediatric low-grade gliomas (pLGGs) to determine either the need for treatment or assess response. Standard methods measure the product of the largest 2 lengths from transverse, anterior-posterior, and cranio-caudal dimensions (SM, cm). This single-institution study evaluated tumor volume measurements (VM, cm) in such pLGGs.

Altered cingulum bundle microstructure in autism spectrum disorder.

Objective: Here, we examined the cingulum bundle, a long-range white matter tract mediating dorsal limbic connectivity, using diffusion tensor imaging (DTI) tractography, in children and adolescents with autism spectrum disorder (ASD) versus controls. We hypothesised that cingulum bundle microstructure would be altered in ASD, based on evidence implicating abnormal white matter connectivity in this disorder.

Methods: DTI data were acquired for 19 ASD participants (IQ ⩾ 70; 7-18 years; mean = 12.

Functional reorganization of the corticospinal tract in a pediatric patient with an arteriovenous malformation.

Presurgical mapping in a pediatric patient diagnosed with arteriovenous malformation in the left hemisphere revealed a case of apparent functional reorganization of a white matter tract. Magnetoencephalography (MEG) was used to identify the motor fields following hand movement. As expected, motor field activity for the left hand was detected in the right hemisphere.

Relations between white matter maturation and reaction time in childhood.

White matter matures with age and is important for the efficient transmission of neuronal signals. Consequently, white matter growth may underlie the development of cognitive processes important for learning, including the speed of information processing. To dissect the relationship between white matter structure and information processing speed, we administered a reaction time task (finger abduction in response to visual cue) to 27 typically developing, right-handed children aged 4 to 13.

Impaired structural connectivity of socio-emotional circuits in autism spectrum disorders: a diffusion tensor imaging study.

Background: Abnormal white matter development may disrupt integration within neural circuits, causing particular impairments in higher-order behaviours. In autism spectrum disorders (ASDs), white matter alterations may contribute to characteristic deficits in complex socio-emotional and communication domains. Here, we used diffusion tensor imaging (DTI) and tract based spatial statistics (TBSS) to evaluate white matter microstructure in ASD.

Cerebello-thalamo-cerebral connections in pediatric brain tumor patients: impact on working memory.

Brain tumors are the leading cause of death and disability from childhood disease in developed countries. Pediatric posterior fossa tumors are often effectively controlled with a combination of surgery, radiation, and chemotherapy, depending on tumor type. White matter injury following resection of tumor and radiation treatment is associated with cognitive declines, including working memory deficits.

White matter maturation in visual and motor areas predicts the latency of visual activation in children.

In humans, white matter maturation is important for the improvement of cognitive function and performance with age. Across studies the variables of white matter maturity and age are highly correlated; however, the unique contributions of white matter to information processing speed remain relatively unknown. We investigated the relations between the speed of the visually-evoked P100m response and the biophysical properties of white matter in 11 healthy children performing a simple, visually-cued finger movement.

White matter integrity and core cognitive function in children diagnosed with sickle cell disease.

Children diagnosed with sickle cell disease (SCD) have an increased risk of stroke, often associated with white matter damage and neurocognitive morbidity. Growing evidence suggests that subtle changes in white matter integrity, which do not pass the threshold to be visible on a clinical magnetic resonance image and classified as stroke, may contribute to decreased cognitive performance. We used archived diffusion-weighted imaging and neurocognitive assessment data to identify associations between microstructural changes in normal-appearing white matter and cognitive performance in children with SCD.

Mapping of the cortical spinal tracts using magnetoencephalography and diffusion tensor tractography in pediatric brain tumor patients.

Prior to resection of a cerebral brain tumor, mapping of the functional and structural anatomy of the adjacent tissue is essential to reduce the risk of damage to descending and ascending pathways. We investigated the effectiveness of concurrent magnetoencephalography (MEG) and diffusion tensor imaging (DTI) tractography to delineate the motor cortex and associated corticospinal tract (CST) in a case series of children with brain tumors seen for pre-surgical evaluation. Using activation points generated from MEG to launch tractography, we delineated the CST of four patients and eight control subjects.

The relations between white matter and declarative memory in older children and adolescents.

Neural communication between the temporal and frontal cortex underlies mature declarative memory skills. The integrity of white matter pathways connecting these regions is likely critical in supporting this communication. Little is known about the relationship between white matter and declarative memory in older children and adolescents, an age period when advanced function in this domain is established.

White matter growth as a mechanism of cognitive development in children.

We examined the functional role of white matter growth in cognitive development. Specifically, we used hierarchical regression analyses to test the unique contributions of age versus white matter integrity in accounting for the development of information processing speed. Diffusion tensor imaging was acquired for 17 children and adolescents (age range 6-17 years), with apparent diffusion coefficient (ADC) and fractional anisotropy (FA) calculated for 10 anatomically defined fiber pathways and 12 regions of hemispheric white matter.

Diffusion tensor imaging of white matter after cranial radiation in children for medulloblastoma: correlation with IQ.

Treatment of children with cranial-spinal radiation (CSR) for brain tumors is associated with adverse intellectual outcome and white matter damage. However, the correlation between IQ and measures of white matter integrity has received little attention. We examined apparent diffusion coefficient (ADC), fractional anisotropy (FA), and intelligence in pediatric patients treated with CSR for medulloblastoma relative to control subjects.

Topographical patterns of lobar atrophy in frontotemporal dementia and Alzheimer's disease.

Background/aims: Fronto-temporal dementia (FTD) designates a group of relatively common neurodegenerative disorders. The aim of this study was to characterize the patterns of brain atrophy in FTD compared to Alzheimer's disease (AD).

Methods: A novel semiautomatic volumetric MRI analysis method was applied to measure regional brain volumes in FTD (n = 15; behavioural variant n = 9, language variant n = 6) in contrast with AD patients (n = 15) and age-matched controls (NC) (n = 15).

Utility of simultaneous brain, CSF and hyperintensity quantification in dementia.

Improved methods of quantifying MRI are needed to study brain-behavior relationships in dementia. Rating scales are variable; lesion-tracing approaches can be subjective and ignore atrophy; segmentation of MRI hyperintensities is complicated by partial volume effects; and hyperintense lesions in different anatomical areas may have different effects. The goal of this study was to extend existing segmentation approaches to include hyperintensities and to demonstrate the utility of simultaneously assessing atrophy and lesion compartments in dementia.