Decreased brain iron deposition based on quantitative susceptibility mapping correlates with reduced neurodevelopmental status in children with autism spectrum disorder

To investigate potential correlations between the susceptibility values of certain brain regions and the severity of disease or neurodevelopmental status in children with autism spectrum disorder (ASD), 18 ASD children and 15 healthy controls (HCs) were recruited. The neurodevelopmental status was assessed by the Gesell Developmental Schedules (GDS) and the severity of the disease was evaluated by the Autism Behavior Checklist (ABC). Eleven brain regions were selected as regions of interest and the susceptibility values were measured by quantitative susceptibility mapping. To evaluate the diagnostic capacity of susceptibility values in distinguishing ASD and HC, the receiver operating characteristic (ROC) curve was computed. Pearson and Spearman partial correlation analysis were used to depict the correlations between the susceptibility values, the ABC scores, and the GDS scores in the ASD group. ROC curves showed that the susceptibility values of the left and right frontal white matter had a larger area under the curve in the ASD group. The susceptibility value of the right globus pallidus was positively correlated with the GDS-fine motor scale score. These findings indicated that the susceptibility value of the right globus pallidus might be a viable imaging biomarker for evaluating the neurodevelopmental status of ASD children.

Evaluation of signal intensity changes in dentate nucleus and globus pallidus on magnetic resonance imaging after intrathecal gadolinium-based contrast agent administration

PURPOSE

Gadolinium deposition has been reported in several normal anatomical structures in the brain after repeated administration of intravenous gadolinium-based contrast agents (GBCAs) used in magnetic resonance imaging (MRI). This study presents preliminary results to see if there is any gadolinium deposition in the dentate nucleus and globus pallidus after using intrathecal GBCAs.

METHODS

Between November 2018 and November 2020, 29 patients who underwent intrathecal contrast-enhanced MR cisternography with the suspicion of rhinorrhea were included in this prospective study. In contrast-enhanced MR cisternography, gadoterate meglumine was administered by intrathecal injection at a dose of 1 ml. One month later, patients had a control MRI with 3D T1 SPACE fat-saturated (FS) and susceptibility weighted images (SWI) sequences. The ratio of dentate nucleus signal intensity to middle cerebellar peduncle signal intensity (DN/MCP ratio) and the ratio of globus pallidus signal intensity to thalamus signal intensity (GP/T ratio) were calculated using region of interest (ROI) on pre-contrast and control MRI sequences.

RESULTS

There was no significant difference for DN/MCP ratio and GP/T ratio on 3D T1 SPACE FS and SWI sequences after intrathecal GBCAs administration compared to baseline MRI.

CONCLUSION

Administration of intrathecal GBCAs did not cause a measurable change in the signal intensity of the dentate nucleus and globus pallidus after a single injection.

Preventing Shift from Pneumocephalus During Deep Brain Stimulation Surgery: Don't Give Up the 'Fork in the Brain'

Clinical vignette

We present the case of a patient who developed intra-operative pneumocephalus during left globus pallidus internus deep brain stimulation (DBS) placement for Parkinson's disease (PD). Microelectrode recording (MER) revealed that we were anterior and lateral to the intended target.

Clinical dilemma

Clinically, we suspected brain shift from pneumocephalus. Removal of the guide-tube for readjustment of the brain target would have resulted in the introduction of movement resulting from brain shift and from displacement from the planned trajectory.

Clinical solution

We elected to leave the guide-tube cannula in place and to pass the final DBS lead into a channel that was located posterior-medially from the center microelectrode pass.

Gap in knowledge

Surgical techniques which can be employed to minimize brain shift in the operating room setting are critical for reduction in variation of the final DBS lead placement. Pneumocephalus after dural opening is one potential cause of brain shift. The recognition that the removal of a guide-tube cannula could worsen brain shift creates an opportunity for an intraoperative team to maintain the advantage of the 'fork' in the brain provided by the initial procedure's requirement of guide-tube placement.

Correlation of age with the size of subcortical nuclei of the brain and its implication in degenerative disease: A magnetic resonance imaging study

Background

Aging is a non-modifiable risk factor for neurodegenerative disease. It is well established that the brain undergoes physiological atrophy with age. So, this study was conducted to analyse the correlation between the age of the person and the size of the various subcortical nuclei of the brain and whether these measurements can serve as a useful indicator for physiological atrophy leading to degenerative disease in clinical practice.

Methods

A total of 600 MRI scans from healthy individuals were examined and the measurements of subcortical nuclei were taken and subsequently analysed.

Results

A statistically significant difference between the genders was observed in the sizes of the axial diameters of caudate nucleus, putamen and globus pallidus. Caudate nucleus transverse diameter showed a moderate negative correlation with age in males. Globus pallidus axial diameter with age showed weak positive correlation for males. Globus pallidus transverse diameter showed weak positive correlation with age for both males and females, but it was stronger for males compared to females.

Conclusions

These results will help neurologists and neurosurgeons in analysing various early degenerative diseases and treat them accordingly.

GPi-DBS-induced brain metabolic activation in cervical dystonia

BACKGROUND

Deep brain stimulation (DBS) of the globus pallidus interna (GPi) is a highly efficacious treatment for cervical dystonia, but its mechanism of action is not fully understood. Here, we investigate the brain metabolic effects of GPi-DBS in cervical dystonia.

METHODS

Eleven patients with GPi-DBS underwent brain 18F-fluorodeoxyglucose positron emission tomography imaging during stimulation on and off. Changes in regional brain glucose metabolism were investigated at the active contact location and across the whole brain. Changes in motor symptom severity were quantified using the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS), executive function using trail making test (TMT) and parkinsonism using Unified Parkinson's Disease Rating Scale (UPDRS).

RESULTS

The mean (SD) best therapeutic response to DBS during the treatment was 81 (22)%. The TWSTRS score was 3.2 (3.9) points lower DBS on compared with off (p=0.02). At the stimulation site, stimulation was associated with increased metabolism, which correlated with DBS stimulation amplitude (r=0.70, p=0.03) but not with changes in motor symptom severity (p>0.9). In the whole brain analysis, stimulation increased metabolism in the GPi, subthalamic nucleus, putamen, primary sensorimotor cortex (PFDR<0.05). Acute improvement in TWSTRS correlated with metabolic activation in the sensorimotor cortex and overall treatment response in the supplementary motor area. Worsening of TMT-B score was associated with activation of the anterior cingulate cortex and parkinsonism with activation in the putamen.

CONCLUSIONS

GPi-DBS increases metabolic activity at the stimulation site and sensorimotor network. The clinical benefit and adverse effects are mediated by modulation of specific networks.

Uncovering neuroanatomical correlates of impaired coordinated movement after pallidal deep brain stimulation

BACKGROUND

The loss of the ability to swim following deep brain stimulation (DBS), although rare, poses a worrisome risk of drowning. It is unclear what anatomic substrate and neural circuitry underlie this phenomenon. We report a case of cervical dystonia with lost ability to swim and dance during active stimulation of globus pallidus internus. We investigated the anatomical underpinning of this phenomenon using unique functional and structural imaging analysis.

METHODS

Tesla (3T) functional MRI (fMRI) of the patient was used during active DBS and compared with a cohort of four matched patients without this side effect. Structural connectivity mapping was used to identify brain network engagement by stimulation.

RESULTS

fMRI during stimulation revealed significant (Pbonferroni<0.0001) stimulation-evoked responses (DBS ON

CONCLUSIONS

These stimulation-induced impairments are likely a manifestation of a broader deficit in interlimb coordination mediated by stimulation effects on the SMA. This neuroanatomical underpinning can help inform future patient-specific stimulation and targeting.

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Key Words

• DYSTONIA
• ELECTRICAL STIMULATION
• FUNCTIONAL IMAGING
• MRI
• NEUROSURGERY

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MESH Headings

• Humans
• Globus Pallidus/diagnostic imaging
• Globus Pallidus/physiology
• Deep Brain Stimulation/adverse effects
• Deep Brain Stimulation/methods
• Treatment Outcome
• Magnetic Resonance Imaging

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Affiliation(s)

Brendan Santyr Division of Neurosurgery, University of Toronto, Toronto, Ontario, Canada
Aaron Loh Division of Neurosurgery, University of Toronto, Toronto, Ontario, Canada
Artur Vetkas Division of Neurosurgery, University of Toronto, Toronto, Ontario, Canada
Dave Gwun Division of Neurosurgery, University of Toronto, Toronto, Ontario, Canada
Wilson Kw Fung Edmond J. Safra Program in Parkinson's Disease and Morton and Gloria Shulman Movement Disorders Centre, Toronto Western Hospital, Toronto, Ontario, Canada
Shakeel Qazi Division of Neurosurgery, University of Toronto, Toronto, Ontario, Canada
Jurgen Germann Division of Neurosurgery, University of Toronto, Toronto, Ontario, Canada
Alexandre Boutet Division of Neurosurgery, University of Toronto, Toronto, Ontario, Canada Joint Department of Medical Imaging, Toronto Western Hospital, Toronto, Ontario, Canada
Can Sarica Division of Neurosurgery, University of Toronto, Toronto, Ontario, Canada
Andrew Yang Division of Neurosurgery, University of Toronto, Toronto, Ontario, Canada
Gavin Elias Division of Neurosurgery, University of Toronto, Toronto, Ontario, Canada
Suneil K Kalia Division of Neurosurgery, University of Toronto, Toronto, Ontario, Canada Krembil Brain Institute, University Health Network, Toronto, Ontario, Canada Center for Advancing Neurotechnological Innovation to Application (CRANIA), University Health Network, Toronto, Ontario, Canada
Alfonso Fasano Edmond J. Safra Program in Parkinson's Disease and Morton and Gloria Shulman Movement Disorders Centre, Toronto Western Hospital, Toronto, Ontario, Canada Krembil Brain Institute, University Health Network, Toronto, Ontario, Canada Center for Advancing Neurotechnological Innovation to Application (CRANIA), University Health Network, Toronto, Ontario, Canada Division of Neurology, University of Toronto, Toronto, Ontario, Canada
Andres M Lozano Division of Neurosurgery, University of Toronto, Toronto, Ontario, Canada Krembil Brain Institute, University Health Network, Toronto, Ontario, Canada

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A novel diagnosis method for schizophrenia based on globus pallidus data

This research aims to diagnose schizophrenia with machine learning-based algorithms. Bayesian neural network, logistic regression, decision tree, k-nearest neighbor, and gaussian kernel classification techniques are investigated to diagnose schizophrenia with data from 125 persons. This study showed that left lateral ventricles and left globus pallidus volumes and their percentages in the brain were significantly lower than HCs in FEP patients. Using brain volumes, we were able to diagnose FEP with an accuracy of 73.6 % via logistic regression and with an accuracy of 86.4 % using the SVM kernel classifier method. Therefore, brain volumes can be used to diagnose FEP with the SVM kernel classifier method.

Bradykinesia and rigidity modulated by functional connectivity between the primary motor cortex and globus pallidus in Parkinson's disease

The mechanisms underlying motor fluctuations in patients with Parkinson's disease (PD) are currently unclear. Regional brain stimulation reported the changing of motor symptoms, but the correlation with functional connectivity (FC) in the brain network is not fully understood. Hence, our study aimed to explore the relationship between motor symptom severity and FC using resting-state functional magnetic resonance imaging (rsfMRI) in the "on" and "off" states of PD. In 26 patients with sporadic PD, FC was assessed using rsfMRI, and clinical severity was analyzed using the motor part of the Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS Part III) in the on and off states. Correlations between FC values and MDS-UPDRS Part III scores were assessed using Pearson's correlation coefficient. The correlation between FC and motor symptoms differed in the on and off states. FC between the ipsilateral precentral gyrus (PreCG) and globus pallidus (GP) correlated with the total MDS-UPDRS Part III scores and those for bradykinesia/rigidity in the off state. Lateralization analysis indicated that FC between the PreCG and GP correlated with the contralateral total MDS-UPDRS Part III scores and those for bradykinesia/rigidity in the off state. Aberrant FC in cortico-striatal circuits correlated with the severity of motor symptoms in PD. Cortico-striatal hyperconnectivity, particularly in motor pathways involving PreCG and GP, is related to motor impairments in PD. These findings may facilitate our understanding of the mechanisms underlying motor symptoms in PD and aid in developing treatment strategies such as brain stimulation for motor impairment.

Aberrant resting-state functional connectivity of the globus pallidus interna in first-episode schizophrenia

BACKGROUND

The striatal-pallidal pathway plays an important role in cognitive control and modulation of behaviors. Globus pallidus interna (GPi), as a primary output structure, is crucial in modulating excitation and inhibition. Studies of GPi in psychiatric illnesses are lacking given the technical challenges of examining this small and functionally diverse subcortical structure.

METHODS

71 medication-naïve first episode schizophrenia (FES) participants and 73 healthy controls (HC) were recruited at the Shanghai Mental Health Center. Clinical symptoms and imaging data were collected at baseline and, in a subset of patients, 8 weeks after initiating treatment. Resting-state functional connectivity of sub-regions of the GP were assessed using a novel mask that combines two atlases to create 8 ROIs in the GP.

RESULTS

Baseline imaging data from 63 FES patients and 55 HC met quality standards and were analyzed. FES patients exhibited less negative connectivity and increased positive connectivity between the right anterior GPi and several cortical and subcortical areas at baseline compared to HC (PFWE < 0.05). Positive functional connectivity between the right anterior GPi and several brain areas, including the right dorsal anterior cingulate gyrus, was associated with severity of positive symptoms (PFWE < 0.05) and predicted treatment response after 8 weeks (n = 28, adjusted R2 = 0.486, p < 0.001).

CONCLUSIONS

Our results implicate striatal-pallidal-thalamic pathways in antipsychotic efficacy. If replicated, these findings may reflect failure of neurodevelopmental processes in adolescence and early adulthood that decrease functional connectivity as an index of failure of the limbic/associative GPi to appropriately inhibit irrelevant signals in psychosis.

White matter connectivity of subthalamic nucleus and globus pallidus interna targets for deep brain stimulation

OBJECTIVE

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) and globus pallidus interna (GPi) have differential therapeutic effects for Parkinson's disease (PD) that drive patient selection. For example, GPi DBS is preferred for dystonic features and dyskinesia, whereas STN DBS has shown faster tremor control and medication reduction. Connectivity studies comparing these two targets, using patient-specific data, are still lacking. The objective was to find STN and GPi structural connectivity patterns in order to better understand differences in DBS-activated brain circuits between these two stimulation targets and to guide optimal contact selection.

METHODS

The authors simulated DBS activation along the main axis of both the STN and GPi by using volume of activated tissue (VAT) modeling with known average stimulation parameters (2.8 V and 60 μsec for STN; 3.3 V and 90 μsec for GPi). The authors modeled VATs in the anterior, middle, and posterior STN and the anterior, midanterior, midposterior, and posterior GPi. The authors generated maps of the connections shared by the patients for each VAT by using probabilistic tractography of diffusion-weighted imaging data obtained in 46 PD patients who underwent DBS (26 with STN and 20 with GPi targeting), and differences between VATs for whole-brain and distal regions of interest (prefrontal cortex, supplementary motor area, primary motor cortex, primary sensory cortex, caudate, motor thalamus, and cerebellum) were generated from structural atlases. Differences between maps were quantified and compared.

RESULTS

VATs across the STN and GPi had different structural connectivity patterns. The authors found significant connectivity differences between VATs for all regions of interest. Posterior and middle STN showed stronger connectivity to the primary motor cortex and supplementary motor area (SMA) (p < 0.001). Posterior STN had the strongest connectivity to the primary sensory cortex and motor thalamus (p < 0.001). Posterior GPi showed stronger connectivity to the primary motor cortex (p < 0.001). Connectivity to the SMA was similar for the posterior and midposterior GPi (p > 0.05), which was greater than that for the anterior GPi (p < 0.001). When both nuclei were compared, posterior and middle STN had stronger connectivity to the SMA, cerebellum, and motor thalamus than GPi (all p < 0.001). Posterior GPi and STN had similar connectivity to the primary sensory cortex.

CONCLUSIONS

On patient-specific imaging, structural connectivity differences existed between GPi and STN DBS, as measured with standardized electrical field modeling of the DBS targets. These connectivity differences may correlate with the differential clinical benefits obtained by targeting each of the two nuclei with DBS for PD. Prospective work is needed to relate these differences to clinical outcomes and to inform targeting and programming.

Acute and Chronic Kernicterus: MR Imaging Evolution of Globus Pallidus Signal Change during Childhood

BACKGROUND AND PURPOSE

Despite its rarity in Western countries, kernicterus resulting from severe neonatal hyperbilirubinemia and its associated neurologic consequences still persists. Subtle MR imaging patterns may be overlooked, leading to diagnostic and prognostic uncertainties. The study systematically analyzes MR imaging pattern over time.

MATERIALS AND METHODS

A retrospective MR imaging study was conducted in Departments of Pediatric Neurology at the University Children's Hospitals in Leipzig, Germany, or Tübingen, Germany, between 2012 and 2022 in patients who presented beyond the neonatal period suspected of having chronic kernicterus.

RESULTS

Eight patients with a total of 15 MR images were identified. The clinical diagnosis of kernicterus was confirmed in all cases on the basis of typical MR imaging findings: Bilateral, diffuse hyperintensity of the globus pallidus was observed in the neonatal period on T1WI (1 MR imaging, at 2 weeks), in infancy on T2WI (4 MR images, at 9-26 months). In children 2 years of age and older, bilateral hyperintensity on T2WI was limited to the borders of the globus pallidus (8 MR images, at 20 months -13 years). Notably, 2 children exhibited normal initial MR imaging findings at 2 months of age. Hence, MR imaging depiction of kernicterus pathology evolves with time, first evident on T1WI, subsequently on T2WI, with a "blind window" during early infancy. The T2WI signal change initially involves the entire globus pallidus and later is limited to the borders. Kernicterus had not been diagnosed in any except 2 patients by previous investigators.

CONCLUSIONS

All patients presented with a characteristic clinical history and signs and an evolving MR imaging pattern. Nonetheless, the diagnosis of kernicterus was frequently missed. Abnormalities on later MR images appear to be underrecognized.

Neuroimaging-based analysis of DBS outcomes in pediatric dystonia: Insights from the GEPESTIM registry

INTRODUCTION

Deep brain stimulation (DBS) is an established treatment in patients of various ages with pharmaco-resistant neurological disorders. Surgical targeting and postoperative programming of DBS depend on the spatial location of the stimulating electrodes in relation to the surrounding anatomical structures, and on electrode connectivity to a specific distribution pattern within brain networks. Such information is usually collected using group-level analysis, which relies on the availability of normative imaging resources (atlases and connectomes). Analysis of DBS data in children with debilitating neurological disorders such as dystonia would benefit from such resources, especially given the developmental differences in neuroimaging data between adults and children. We assembled pediatric normative neuroimaging resources from open-access datasets in order to comply with age-related anatomical and functional differences in pediatric DBS populations. We illustrated their utility in a cohort of children with dystonia treated with pallidal DBS. We aimed to derive a local pallidal sweetspot and explore a connectivity fingerprint associated with pallidal stimulation to exemplify the utility of the assembled imaging resources.

METHODS

An average pediatric brain template (the MNI brain template 4.5-18.5 years) was implemented and used to localize the DBS electrodes in 20 patients from the GEPESTIM registry cohort. A pediatric subcortical atlas, analogous to the DISTAL atlas known in DBS research, was also employed to highlight the anatomical structures of interest. A local pallidal sweetspot was modeled, and its degree of overlap with stimulation volumes was calculated as a correlate of individual clinical outcomes. Additionally, a pediatric functional connectome of 100 neurotypical subjects from the Consortium for Reliability and Reproducibility was built to allow network-based analyses and decipher a connectivity fingerprint responsible for the clinical improvements in our cohort.

RESULTS

We successfully implemented a pediatric neuroimaging dataset that will be made available for public use as a tool for DBS analyses. Overlap of stimulation volumes with the identified DBS-sweetspot model correlated significantly with improvement on a local spatial level (R = 0.46, permuted p = 0.019). The functional connectivity fingerprint of DBS outcomes was determined to be a network correlate of therapeutic pallidal stimulation in children with dystonia (R = 0.30, permuted p = 0.003).

CONCLUSIONS

Local sweetspot and distributed network models provide neuroanatomical substrates for DBS-associated clinical outcomes in dystonia using pediatric neuroimaging surrogate data. Implementation of this pediatric neuroimaging dataset might help to improve the practice and pave the road towards a personalized DBS-neuroimaging analyses in pediatric patients.

Parkinson's disease may disrupt overlapping subthalamic nucleus and pallidal motor networks

There is an ongoing debate about differential clinical outcome and associated adverse effects of deep brain stimulation (DBS) in Parkinson's disease (PD) targeting the subthalamic nucleus (STN) or the globus pallidus pars interna (GPi). Given that functional connectivity profiles suggest beneficial DBS effects within a common network, the empirical evidence about the underlying anatomical circuitry is still scarce. Therefore, we investigate the STN and GPi-associated structural covariance brain patterns in PD patients and healthy controls. We estimate GPi's and STN's whole-brain structural covariance from magnetic resonance imaging (MRI) in a normative mid- to old-age community-dwelling cohort (n = 1184) across maps of grey matter volume, magnetization transfer (MT) saturation, longitudinal relaxation rate (R1), effective transversal relaxation rate (R2*) and effective proton density (PD*). We compare these with the structural covariance estimates in patients with idiopathic PD (n = 32) followed by validation using a reduced size controls' cohort (n = 32). In the normative data set, we observed overlapping spatially distributed cortical and subcortical covariance patterns across maps confined to basal ganglia, thalamus, motor, and premotor cortical areas. Only the subcortical and midline motor cortical areas were confirmed in the reduced size cohort. These findings contrasted with the absence of structural covariance with cortical areas in the PD cohort. We interpret with caution the differential covariance maps of overlapping STN and GPi networks in patients with PD and healthy controls as correlates of motor network disruption. Our study provides face validity to the proposed extension of the currently existing structural covariance methods based on morphometry features to multiparameter MRI sensitive to brain tissue microstructure.

Resting-state functional connectivity disruption between the left and right pallidum as a biomarker for subthreshold depression

Although the identification of late adolescents with subthreshold depression (StD) may provide a basis for developing effective interventions that could lead to a reduction in the prevalence of StD and prevent the development of major depressive disorder, knowledge about the neural basis of StD remains limited. The purpose of this study was to develop a generalizable classifier for StD and to shed light on the underlying neural mechanisms of StD in late adolescents. Resting-state functional magnetic resonance imaging data of 91 individuals (30 StD subjects, 61 healthy controls) were included to build an StD classifier, and eight functional connections were selected by using the combination of two machine learning algorithms. We applied this biomarker to an independent cohort (n = 43) and confirmed that it showed generalization performance (area under the curve = 0.84/0.75 for the training/test datasets). Moreover, the most important functional connection was between the left and right pallidum, which may be related to clinically important dysfunctions in subjects with StD such as anhedonia and hyposensitivity to rewards. Investigation of whether modulation of the identified functional connections can be an effective treatment for StD may be an important topic of future research.

Serum biomarkers of liver fibrosis identify globus pallidus vulnerability

The CNS manifestation of chronic liver disease can include magnetic resonance (MR) signal hyperintensities in basal ganglia structures. Here, relations between liver (serum-derived fibrosis scores) and brain (regional T1-weighted signal intensities and volumes) integrity were evaluated in a sample of 457 individuals including those with alcohol use disorders (AUD), people living with human immunodeficiency virus (HIV), those comorbid for AUD and HIV, and healthy controls. Liver fibrosis was identified from cutoff scores as follows: aspartate aminotransferase to platelet ratio index (APRI) > 0.7 in 9.4% (n = 43) of the cohort; fibrosis score (FIB4) > 1.5 in 28.0% (n = 128) of the cohort; and non-alcoholic fatty liver disease fibrosis score (NFS) > -1.4 in 30.2% (n = 138) of the cohort. Presence of serum-derived liver fibrosis was associated with high signal intensities selective to basal ganglia (i.e., caudate, putamen, and pallidum) structures. High signal intensities in the pallidum, however, explained a significant portion of the variance in APRI (25.0%) and FIB4 (23.6%) cutoff scores. Further, among the regions evaluated, only the globus pallidus showed a correlation between greater signal intensity and smaller volume (r = -0.44, p <.0001). Finally, higher pallidal signal intensity correlated worse ataxia (eyes open ρ = -0.23, p =.0002; eyes closed ρ = -0.21, p =.0005). This study suggests that clinically relevant serum biomarkers of liver fibrosis such as the APRI may identify individuals vulnerable to globus pallidus pathology and contribute to problems with postural balance.

An artificial intelligence algorithm for analyzing globus pallidus necrosis after carbon monoxide intoxication

Globus pallidus necrosis (GPN) is one of typical neurological imaging features in patients with carbon monoxide (CO) poisoning. Current clinical guideline recommends neurological imaging examination for CO-intoxicated patients with conscious disturbance rather than routine screening, which may lead to undiagnosed GPN. We aimed to develop an artificial intelligence algorithm for predicting GPN in CO intoxication patients. We included CO intoxication patients with neurological images between 2000 and 2019 in Chang Gung Memorial Hospital. We collected 41 clinical and laboratory parameters on the first day of admission for algorithm development. We used fivefold cross validation and applied several machine learning algorithms. Random forest classifier (RFC) provided the best predictive performance in our cohort. Among the 261 patients with CO intoxication, 52 patients presented with GPN. The artificial intelligence algorithm using the RFC-based AI model achieved an accuracy = 79.2 ± 2.6%, sensitivity = 77.7%, precision score = 81.9 ± 3.4%, and F1 score = 73.2 ± 1.8%. The area under receiver operating characteristic was approximately 0.64. Top five weighted variables were Platelet count, carboxyhemoglobin, Glasgow Coma scale, creatinine, and hemoglobin. Our RFC-based algorithm is the first to predict GPN in patients with CO intoxication and provides fair predictive ability. Further studies are needed to validate our findings.

Intracranial and subcortical volumes in adolescents with early-onset psychosis: A multisite mega-analysis from the ENIGMA consortium

Early-onset psychosis disorders are serious mental disorders arising before the age of 18 years. Here, we investigate the largest neuroimaging dataset, to date, of patients with early-onset psychosis and healthy controls for differences in intracranial and subcortical brain volumes. The sample included 263 patients with early-onset psychosis (mean age: 16.4 ± 1.4 years, mean illness duration: 1.5 ± 1.4 years, 39.2% female) and 359 healthy controls (mean age: 15.9 ± 1.7 years, 45.4% female) with magnetic resonance imaging data, pooled from 11 clinical cohorts. Patients were diagnosed with early-onset schizophrenia (n = 183), affective psychosis (n = 39), or other psychotic disorders (n = 41). We used linear mixed-effects models to investigate differences in intracranial and subcortical volumes across the patient sample, diagnostic subgroup and antipsychotic medication, relative to controls. We observed significantly lower intracranial (Cohen's d = -0.39) and hippocampal (d = -0.25) volumes, and higher caudate (d = 0.25) and pallidum (d = 0.24) volumes in patients relative to controls. Intracranial volume was lower in both early-onset schizophrenia (d = -0.34) and affective psychosis (d = -0.42), and early-onset schizophrenia showed lower hippocampal (d = -0.24) and higher pallidum (d = 0.29) volumes. Patients who were currently treated with antipsychotic medication (n = 193) had significantly lower intracranial volume (d = -0.42). The findings demonstrate a similar pattern of brain alterations in early-onset psychosis as previously reported in adult psychosis, but with notably low intracranial volume. The low intracranial volume suggests disrupted neurodevelopment in adolescent early-onset psychosis.

Neurodegeneration of the Globus Pallidus Internus as a Neural Correlate to Dopa-Response in Freezing of Gait

BACKGROUND

Background: Parkinson's disease (PD) patients who develop freezing of gait (FOG) have reduced mobility and independence. While some patients experience improvement in their FOG symptoms with dopaminergic therapies, a subset of patients have little to no response. To date, it is unknown what changes in brain structure underlie dopa-response and whether this can be measured using neuroimaging approaches.

OBJECTIVE

We tested the hypothesis that structural integrity of brain regions (subthalamic nucleus and globus pallidus internus, GPi) which link basal ganglia to the mesencephalic locomotor region (MLR), a region involved in automatic gait, would be associated with FOG response to dopaminergic therapy.

METHODS

In this observational study, thirty-six participants with PD and definite FOG were recruited to undergo diffusion kurtosis imaging (DKI) and multiple assessments of dopa responsiveness (UPDRS scores, gait times ON versus OFF medication).

RESULTS

The right GPi in participants with dopa-unresponsive FOG showed reduced fractional anisotropy, mean kurtosis (MK), and increased radial diffusivity relative to those with dopa-responsive FOG. Furthermore, using probabilistic tractography, we observed reduced MK and increased mean diffusivity along the right GPi-MLR tract in dopa-unresponsive FOG. MK in the right GPi was associated with a subjective dopa-response for FOG (r = -0.360, df = 30, p = 0.043) but not overall motor dopa-response.

CONCLUSION

These results support structural integrity of the GPi as a correlate to dopa-response in FOG. Additionally, this study suggests DKI metrics may be a sensitive biomarker for clinical studies targeting dopaminergic circuitry and improvements in FOG behavior.

Paradoxical paramagnetic calcifications in the globus pallidus: An ex vivo MR investigation and histological validation study

MR images based on phase contrast images have gained clinical interest as an in vivo tool for assessing anatomical and histological findings. The globus pallidus is an area of major iron metabolism and storage in the brain tissue. Calcium, another important metal in the body, is frequently deposited in the globus pallidus as well. Recently, we observed dense paramagnetic deposition with paradoxical calcifications in the globus pallidus and putamen. In this work, we explore detailed MR findings on these structures, and the histological source of the related findings using ex vivo CT and MR images. Ex vivo MR was obtained with a maximum 100 μm³ isotropic resolution using a 15.2 T MR system. 3D gradient echo images and quantitative susceptibility mapping were used because of their good sensitivity to metallic deposition, high signal-to-noise ratio, and excellent contrast to iron and calcium. We found dense paramagnetic deposition along the perforating arteries in the globus pallidus. This paramagnetic deposition was hyperdense on ex vivo CT scans. Histological studies confirmed this finding, and simultaneous deposition of iron and calcium, although more iron dominant, was observed along the vessel walls of the globus pallidus. This was an exclusive finding for the penetrating arteries of the globus pallidus. Thus, our results suggest that several strong and paradoxical paramagnetic sources at the globus pallidus can be associated with vascular degeneration.

Deep-learning based fully automatic segmentation of the globus pallidus interna and externa using ultra-high 7 Tesla MRI

Deep brain stimulation (DBS) surgery has been shown to dramatically improve the quality of life for patients with various motor dysfunctions, such as those afflicted with Parkinson's disease (PD), dystonia, and essential tremor (ET), by relieving motor symptoms associated with such pathologies. The success of DBS procedures is directly related to the proper placement of the electrodes, which requires the ability to accurately detect and identify relevant target structures within the subcortical basal ganglia region. In particular, accurate and reliable segmentation of the globus pallidus (GP) interna is of great interest for DBS surgery for PD and dystonia. In this study, we present a deep-learning based neural network, which we term GP-net, for the automatic segmentation of both the external and internal segments of the globus pallidus. High resolution 7 Tesla images from 101 subjects were used in this study; GP-net is trained on a cohort of 58 subjects, containing patients with movement disorders as well as healthy control subjects. GP-net performs 3D inference in a patient-specific manner, alleviating the need for atlas-based segmentation. GP-net was extensively validated, both quantitatively and qualitatively over 43 test subjects including patients with movement disorders and healthy control and is shown to consistently produce improved segmentation results compared with state-of-the-art atlas-based segmentations. We also demonstrate a postoperative lead location assessment with respect to a segmented globus pallidus obtained by GP-net.

Tuber Locations Associated with Infantile Spasms Map to a Common Brain Network

OBJECTIVE

Approximately 50% of patients with tuberous sclerosis complex develop infantile spasms, a sudden onset epilepsy syndrome associated with poor neurological outcomes. An increased burden of tubers confers an elevated risk of infantile spasms, but it remains unknown whether some tuber locations confer higher risk than others. Here, we test whether tuber location and connectivity are associated with infantile spasms.

METHODS

We segmented tubers from 123 children with (n = 74) and without (n = 49) infantile spasms from a prospective observational cohort. We used voxelwise lesion symptom mapping to test for an association between spasms and tuber location. We then used lesion network mapping to test for an association between spasms and connectivity with tuber locations. Finally, we tested the discriminability of identified associations with logistic regression and cross-validation as well as statistical mediation.

RESULTS

Tuber locations associated with infantile spasms were heterogenous, and no single location was significantly associated with spasms. However, >95% of tuber locations associated with spasms were functionally connected to the globi pallidi and cerebellar vermis. These connections were specific compared to tubers in patients without spasms. Logistic regression found that globus pallidus connectivity was a stronger predictor of spasms (odds ratio [OR] = 1.96, 95% confidence interval [CI] = 1.10-3.50, p = 0.02) than tuber burden (OR = 1.65, 95% CI = 0.90-3.04, p = 0.11), with a mean receiver operating characteristic area under the curve of 0.73 (±0.1) during repeated cross-validation.

INTERPRETATION

Connectivity between tuber locations and the bilateral globi pallidi is associated with infantile spasms. Our findings lend insight into spasm pathophysiology and may identify patients at risk. ANN NEUROL 2021;89:726-739.

Allosteric Interactions between Adenosine A2A and Dopamine D2 Receptors in Heteromeric Complexes: Biochemical and Pharmacological Characteristics, and Opportunities for PET Imaging

Adenosine and dopamine interact antagonistically in living mammals. These interactions are mediated via adenosine A_2A and dopamine D₂ receptors (R). Stimulation of A_2AR inhibits and blockade of A_2AR enhances D₂R-mediated locomotor activation and goal-directed behavior in rodents. In striatal membrane preparations, adenosine decreases both the affinity and the signal transduction of D₂R via its interaction with A_2AR. Reciprocal A_2AR/D₂R interactions occur mainly in striatopallidal GABAergic medium spiny neurons (MSNs) of the indirect pathway that are involved in motor control, and in striatal astrocytes. In the nucleus accumbens, they also take place in MSNs involved in reward-related behavior. A_2AR and D₂R co-aggregate, co-internalize, and co-desensitize. They are at very close distance in biomembranes and form heteromers. Antagonistic interactions between adenosine and dopamine are (at least partially) caused by allosteric receptor–receptor interactions within A_2AR/D₂R heteromeric complexes. Such interactions may be exploited in novel strategies for the treatment of Parkinson’s disease, schizophrenia, substance abuse, and perhaps also attention deficit-hyperactivity disorder. Little is known about shifting A_2AR/D₂R heteromer/homodimer equilibria in the brain. Positron emission tomography with suitable ligands may provide in vivo information about receptor crosstalk in the living organism. Some experimental approaches, and strategies for the design of novel imaging agents (e.g., heterobivalent ligands) are proposed in this review.

3 versus 7 Tesla magnetic resonance imaging for parcellations of subcortical brain structures in clinical settings

7 Tesla (7T) magnetic resonance imaging holds great promise for improved visualization of the human brain for clinical purposes. To assess whether 7T is superior regarding localization procedures of small brain structures, we compared manual parcellations of the red nucleus, subthalamic nucleus, substantia nigra, globus pallidus interna and externa. These parcellations were created on a commonly used clinical anisotropic clinical 3T with an optimized isotropic (o)3T and standard 7T scan. The clinical 3T MRI scans did not allow delineation of an anatomically plausible structure due to its limited spatial resolution. o3T and 7T parcellations were directly compared. We found that 7T outperformed the o3T MRI as reflected by higher Dice scores, which were used as a measurement of interrater agreement for manual parcellations on quantitative susceptibility maps. This increase in agreement was associated with higher contrast to noise ratios for smaller structures, but not for the larger globus pallidus segments. Additionally, control-analyses were performed to account for potential biases in manual parcellations by assessing semi-automatic parcellations. These results showed a higher consistency for structure volumes for 7T compared to optimized 3T which illustrates the importance of the use of isotropic voxels for 3D visualization of the surgical target area. Together these results indicate that 7T outperforms c3T as well as o3T given the constraints of a clinical setting.

Improved depiction of subthalamic nucleus and globus pallidus internus with optimized high-resolution quantitative susceptibility mapping at 7 T

The subthalamic nucleus (STN) and globus pallidus internus (GPi) are commonly used targets in deep-brain stimulation (DBS) surgery for the treatment of movement disorders. The success of DBS critically depends on the spatial precision of stimulation. By taking advantage of good contrast between iron-rich deep-brain nuclei and surrounding tissues, quantitative susceptibility mapping (QSM) has shown promise in differentiating the STN and GPi from the adjacent substantia nigra and globus pallidus externus, respectively. Nonlinear morphology-enabled dipole inversion (NMEDI) is a widely used QSM algorithm, but the image quality of reconstructed susceptibility maps relies on the regularization parameter selection. To date, few studies have systematically optimized the regularization parameter at the ultra-high field of 7 T. In this study, we optimized the regularization parameter in NMEDI to improve the depiction of STN and GPi at different spatial resolutions at both 3 T and 7 T. The optimized QSM images were further compared with other susceptibility-based images, including T2*-weighted (T2*w), R2*, susceptibility-weighted, and phase images. QSM showed better depiction of deep-brain nuclei with clearer boundaries compared with the other methods, and 7 T QSM at 0.35 × 0.35 × 1.0 mm³ demonstrated superior performance to the others. Our findings suggest that optimized high-resolution QSM at 7 T allows for improved delineation of deep-brain nuclei with clear and sharp borders between nuclei, which may become a promising tool for DBS nucleus preoperative localization.

Associations of quantitative susceptibility mapping with Alzheimer's disease clinical and imaging markers

Altered iron metabolism has been hypothesized to be associated with Alzheimer’s disease pathology, and prior work has shown associations between iron load and beta amyloid plaques. Quantitative susceptibility mapping (QSM) is a recently popularized MR technique to infer local tissue susceptibility secondary to the presence of iron as well as other minerals. Greater QSM values imply greater iron concentration in tissue. QSM has been used to study relationships between cerebral iron load and established markers of Alzheimer’s disease, however relationships remain unclear. In this work we study QSM signal characteristics and associations between susceptibility measured on QSM and established clinical and imaging markers of Alzheimer’s disease. The study included 421 participants (234 male, median age 70 years, range 34–97 years) from the Mayo Clinic Study of Aging and Alzheimer’s Disease Research Center; 296 (70%) had a diagnosis of cognitively unimpaired, 69 (16%) mild cognitive impairment, and 56 (13%) amnestic dementia. All participants had multi-echo gradient recalled echo imaging, PiB amyloid PET, and Tauvid tau PET. Variance components analysis showed that variation in cortical susceptibility across participants was low. Linear regression models were fit to assess associations with regional susceptibility. Expected increases in susceptibility were found with older age and cognitive impairment in the deep and inferior gray nuclei (pallidum, putamen, substantia nigra, subthalamic nucleus) (betas: 0.0017 to 0.0053 ppm for a 10 year increase in age, p = 0.03 to < 0.001; betas: 0.0021 to 0.0058 ppm for a 5 point decrease in Short Test of Mental Status, p = 0.003 to p < 0.001). Effect sizes in cortical regions were smaller, and the age associations were generally negative. Higher susceptibility was significantly associated with higher amyloid PET SUVR in the pallidum and putamen (betas: 0.0029 and 0.0012 ppm for a 20% increase in amyloid PET, p = 0.05 and 0.02, respectively), higher tau PET in the basal ganglia with the largest effect size in the pallidum (0.0082 ppm for a 20% increase in tau PET, p < 0.001), and with lower cortical gray matter volume in the medial temporal lobe (0.0006 ppm for a 20% decrease in volume, p = 0.03). Overall, these findings suggest that susceptibility in the deep and inferior gray nuclei, particularly the pallidum and putamen, may be a marker of cognitive decline, amyloid deposition, and off-target binding of the tau ligand. Although iron has been demonstrated in amyloid plaques and in association with neurodegeneration, it is of insufficient quantity to be reliably detected in the cortex using this implementation of QSM.

Anatomical Characterization of the Human Structural Connectivity between the Pedunculopontine Nucleus and Globus Pallidus via Multi-Shell Multi-Tissue Tractography

Background and objectives: The internal (GPi) and external segments (GPe) of the globus pallidus represent key nodes in the basal ganglia system. Connections to and from pallidal segments are topographically organized, delineating limbic, associative and sensorimotor territories. The topography of pallidal afferent and efferent connections with brainstem structures has been poorly investigated. In this study we sought to characterize in-vivo connections between the globus pallidus and the pedunculopontine nucleus (PPN) via diffusion tractography. Materials and Methods: We employed structural and diffusion data of 100 subjects from the Human Connectome Project repository in order to reconstruct the connections between the PPN and the globus pallidus, employing higher order tractography techniques. We assessed streamline count of the reconstructed bundles and investigated spatial relations between pallidal voxels connected to the PPN and pallidal limbic, associative and sensorimotor functional territories. Results: We successfully reconstructed pallidotegmental tracts for the GPi and GPe in all subjects. The number of streamlines connecting the PPN with the GPi was greater than the number of those joining it with the GPe. PPN maps within pallidal segments exhibited a distinctive spatial organization, being localized in the ventromedial portion of the GPi and in the ventral-anterior portion in the GPe. Regarding their spatial relations with tractography-derived maps of pallidal functional territories, the highest value of percentage overlap was noticed between PPN maps and the associative territory. Conclusions: We successfully reconstructed the anatomical course of the pallidotegmental pathways and comprehensively characterized their topographical arrangement within both pallidal segments. PPM maps were localized in the ventromedial aspect of the GPi, while they occupied the anterior pole and the most ventral portion of the GPe. A better understanding of the spatial and topographical arrangement of the pallidotegmental pathways may have pathophysiological and therapeutic implications in movement disorders.

Genetic and environmental influences on corticostriatal circuits in twins with autism

BACKGROUND

Corticostriatal circuits (CSC) have been implicated in the presentation of some restricted and repetitive behaviours (RRBs) in children with autism-spectrum disorder (ASD), and preliminary evidence suggests that disruptions in these pathways may be associated with differences in genetic and environmental influences on brain development. The objective of this investigation was to examine the impact of genetic and environmental factors on CSC regions in twins with and without ASD and to evaluate their relationship with the severity of RRBs.

METHODS

We obtained T1-weighted MRIs from same-sex monozygotic and dizygotic twin pairs, aged 6–15 years. Good-quality data were available from 48 ASD pairs (n = 96 twins; 30 pairs concordant for ASD, 15 monozygotic and 15 dizygotic; 18 pairs discordant for ASD, 4 monozygotic and 14 dizygotic) and 34 typically developing control pairs (n = 68 twins; 20 monozygotic and 14 dizygotic pairs). We generated structural measures of the orbitofrontal cortex (OFC), anterior cingulate cortex (ACC), caudate, putamen, pallidum and thalamus using FreeSurfer. Twin pair comparisons included intraclass correlation analyses and ACE modelling (a2 = additive genetics; c2 = common or shared environment; e2 = unique or nonshared environment). We also assessed correlations with RRB severity.

RESULTS

Structural variation in CSC regions was predominantly genetically mediated in typically developing twins (a2 = 0.56 to 0.87), except for ACC white matter volume (a2 = 0.42, 95% confidence interval [CI] 0.08 to 0.77). We also observed similar magnitudes of genetic influence in twins with ASD (a2 = 0.65 to 0.97), but the cortical thickness of the ACC (c2 = 0.44, 95% CI 0.22 to 0.66) and OFC (c2 = 0.60, 95% CI 0.25 to 0.95) was primarily associated with environmental factors in only twins with ASD. Twin pair differences in OFC grey matter volume were also correlated with RRB severity and were predominantly environmentally mediated.

LIMITATIONS

We obtained MRIs on 2 scanners, and analytical approaches could not identify specific genetic and environmental factors.

CONCLUSION

Genetic factors primarily contribute to structural variation in subcortical CSC regions, regardless of ASD, but environmental factors may exert a greater influence on the development of grey matter thickness in the OFC and ACC in children with ASD. The increased vulnerability of OFC grey matter to environmental influences may also mediate some heterogeneity in RRB severity in children with ASD.

Alcohol effects on globus pallidus connectivity: Role of impulsivity and binge drinking

Despite the harm caused by binge drinking, the neural mechanisms leading to risky and disinhibited intoxication-related behaviors are not well understood. Evidence suggests that the globus pallidus externus (GPe), a substructure within the basal ganglia, participates in inhibitory control processes, as examined in stop-signaling tasks. In fact, studies in rodents have revealed that alcohol can change GPe activity by decreasing neuronal firing rates, suggesting that the GPe may have a central role in explaining impulsive behaviors and failures of inhibition that occur during binge drinking. In this study, twenty-five healthy volunteers underwent intravenous alcohol infusion to achieve a blood alcohol level of 0.08 g/dl, which is equivalent to a binge drinking episode. A resting state functional magnetic resonance imaging scan was collected prior to the infusion and at binge-level exposure. Functional connectivity analysis was used to investigate the association between alcohol-induced changes in GPe connectivity, drinking behaviors, and impulsivity traits. We found that individuals with greater number of drinks or heavy drinking days in the recent past had greater alcohol-induced deficits in GPe connectivity, particularly to the striatum. Our data also indicated an association between impulsivity and alcohol-induced deficits in GPe-frontal/precentral connectivity. Moreover, alcohol induced changes in GPe-amygdala circuitry suggested greater vulnerabilities to stress-related drinking in some individuals. Taken together, these findings suggest that alcohol may interact with impulsive personality traits and drinking patterns to drive alterations in GPe circuitry associated with behavioral inhibition, possibly indicating a neural mechanism by which binge drinking could lead to impulsive behaviors.

Independent support for corticopallidal contributions to schizophrenia-related functional impairment

BACKGROUND

Abnormalities between the prefrontal cortex and basal ganglia have been described by numerous studies of schizophrenia (SZ). We recently reported that individuals with first episode SZ who develop greater vocational and social impairments show lower baseline functional connectivity between the globus pallidus (GP) and regions of the intrinsic salience network. Here we extend these findings to probe the integrity of this system in individuals with chronic illness.

METHODS

All data were obtained from a publicly available Center of Biomedical Research Excellence dataset (http://fcon_1000.

PROJECTS

nitric.org/indi/retro/cobre.html) that included resting-state fMRI and structural scans, and an array of clinical and neuropsychological measures. Participants with SZ were divided into high- or low-functioning groups based on scores across measures of psychopathology and cognitive functioning. Corticopallidal functional connectivity was examined between low- and high-functioning individuals with SZ and matched healthy control participants. We focused on connectivity between GP structures and a priori regions of the salience network that were significant in our previous study. Exploratory voxel-wise analyses were also conducted.

RESULTS

Lower functioning individuals with SZ demonstrated less connectivity between bilateral GP externa and nodes within the salience network, relative to healthy controls. No connectivity differences were observed between low- and high-functioning individuals with SZ. Exploratory voxel-wise analyses highlighted additional large-scale corticopallidal abnormalities in lower-functioning participants with SZ.

CONCLUSIONS

These results confirm our previous work in a more chronic cohort of individuals with SZ. Our findings further advance corticopallidal connectivity as a biomarker of functional impairments in SZ and lay the groundwork for treatment-based studies.

Adolescent Psychopathic Traits Negatively Relate to Hemodynamic Activity within the Basal Ganglia during Error-Related Processing

Youth with elevated psychopathic traits exhibit a number of comparable neurocognitive deficits as adult psychopathic offenders, including error-related processing deficits. Subregions of the basal ganglia play an important, though indirect, role in error-related processing through connections with cortical areas including the anterior cingulate cortex. A number of recent structural and functional magnetic resonance imaging (s/fMRI) studies have associated basal ganglia dysfunction in youth with elevated psychopathic traits, but these studies have not examined whether dysfunction occurring within subregions of the basal ganglia help contribute to error-related processing deficits previously observed in such at-risk youth. Here, we investigated error-related processing using a response inhibition Go/NoGo fMRI experimental paradigm in a large sample of incarcerated male adolescent offenders (n = 182). In the current report, psychopathy scores (measured via the Psychopathy Checklist: Youth Version (PCL:YV)) were negatively related to hemodynamic activity within input nuclei of the basal ganglia (i.e., the caudate and nucleus accumbens), as well as intrinsic/output nuclei (i.e., the globus pallidus and substantia nigra) and related nuclei (i.e., the subthalamic nucleus) during error-related processing. This is the first evidence to suggest that error-related dysfunction previously observed in youth with elevated psychopathic traits may be related to underlying abnormalities occurring within subregions of the basal ganglia.

Gadoterate Meglumine Administration in Multiple Sclerosis has no Effect on the Dentate Nucleus and the Globus Pallidus Signal Intensities

RATIONALE AND OBJECTIVES

Previous studies on possible accumulation of gadolinium-based contrast agents (GBCA) in the brain suggest that macrocyclic GBCA are less likely to accumulate than linear GBCA. However, conflicting results have been reported, especially in MS. The aim of this study is to investigate retrospectively the correlation between gadoterate-meglumine (macrocyclic GBCA) use and T1 signal intensity changes (SI) in the dentate nucleus and the GP on unenhanced T1-weighted images in a large cohort of MS patients.

MATERIALS AND METHODS

Unenhanced T1-weighted images of 232 MS patients who previously received multiple intravenous administrations of 0.1 mmol/kg of gadoterate-meglumine were reviewed. The change in T1 SI ratios of dentate nucleus/central pons (DN/CP) and globus pallidus/centrum semiovale (GP/CSO) was calculated between the first and last MRIs and correlated with age, number of injections, time interval between MRIs, disease duration, activity, and therapy.

RESULTS

DN/CP ratio showed no significant changes whereas the GP/CSO ratio showed a significant decrease (p < 0.0001) between the first and last MRIs. Multivariable analyses of both ratios, controlling for age, disease duration, and time interval between MRIs, showed no significant correlation between the number of gadolinium injections and the differences in DN/CP (standardized beta = -0.018, p = 0.811) or GP/CSO SI ratios (standardized beta = -0.049, p = 0.499).

CONCLUSION

Repeated administration of gadoterate-meglumine in MS patients did not result in increased T1 SI in the DN or the GP. The significant decrease of GP/CSO ratio between the first and last MRIs is not due to gadolinium accumulation but rather to varying MR parameters.

Multi-modal imaging with specialized sequences improves accuracy of the automated subcortical grey matter segmentation

The basal ganglia and limbic system, particularly the thalamus, putamen, internal and external globus pallidus, substantia nigra, and sub-thalamic nucleus, comprise a clinically relevant signal network for Parkinson's disease. In order to manually trace these structures, a combination of high-resolution and specialized sequences at 7 T are used, but it is not feasible to routinely scan clinical patients in those scanners. Targeted imaging sequences at 3 T have been presented to enhance contrast in a select group of these structures. In this work, we show that a series of atlases generated at 7 T can be used to accurately segment these structures at 3 T using a combination of standard and optimized imaging sequences, though no one approach provided the best result across all structures. In the thalamus and putamen, a median Dice Similarity Coefficient (DSC) over 0.88 and a mean surface distance <1.0 mm were achieved using a combination of T1 and an optimized inversion recovery imaging sequences. In the internal and external globus pallidus a DSC over 0.75 and a mean surface distance <1.2 mm were achieved using a combination of T1 and inversion recovery imaging sequences. In the substantia nigra and sub-thalamic nucleus a DSC of over 0.6 and a mean surface distance of <1.0 mm were achieved using the inversion recovery imaging sequence. On average, using T1 and optimized inversion recovery together significantly improved segmentation results than over individual modality (p < 0.05 Wilcoxon sign-rank test).

MR susceptibility contrast imaging using a 2D simultaneous multi-slice gradient-echo sequence at 7T

Purpose

To develop a 7T simultaneous multi-slice (SMS) 2D gradient-echo sequence for susceptibility contrast imaging, and to compare its quality to 3D imaging.

Methods

A frequency modulated and phase cycled RF pulse was designed to simultaneously excite multiple slices in multi-echo 2D gradient-echo imaging. The imaging parameters were chosen to generate images with susceptibility contrast, including T₂*-weighted magnitude/phase images, susceptibility-weighted images and quantitative susceptibility/R₂* maps. To compare their image quality with 3D gradient-echo imaging, both 2D and 3D imaging were performed on 11 healthy volunteers and 4 patients with multiple sclerosis (MS). The signal to noise ratio (SNR) in gray and white matter and their contrast to noise ratio (CNR) was simulated for the 2D and 3D magnitude images using parameters from the imaging. The experimental SNRs and CNRs were measured in gray/white matter and deep gray matter structures on magnitude, phase, R₂* and QSM images from volunteers and the visibility of MS lesions on these images from patients was visually rated. All SNRs and CNRs were compared between the 2D and 3D imaging using a paired t-test.

Results

Although the 3D magnitude images still had significantly higher SNRs (by 13.0~17.6%), the 2D magnitude and QSM images generated significantly higher gray/white matter or globus pallidus/putamen contrast (by 13.3~87.5%) and significantly higher MS lesion contrast (by 5.9~17.3%).

Conclusion

2D SMS gradient-echo imaging can serve as an alternative to often used 3D imaging to obtain susceptibility-contrast-weighted images, with an advantage of providing better image contrast and MS lesion sensitivity.

Axonal degeneration in Parkinson's disease - Basal ganglia circuitry and D2 receptor availability

Basal ganglia (BG) circuitry plays a crucial role in the control of movement. Degeneration of its pathways and imbalance of dopaminergic signalling goes along with movement disorders such as Parkinson's disease. In this study, we explore the interaction of degeneration in two BG pathways (the nigro-striatal and dentato-pallidal pathway) with D2 receptor signalling to elucidate an association to motor impairment and medication response. Included in the study were 24 parkinsonian patients [male, 62 years (± 9.3 SD)] compared to 24 healthy controls [male, 63 years (± 10.2 SD)]; each participant passed through three phases of the study (i) acquisition of metadata/clinical testing, (ii) genotyping and (iii) anatomical/diffusion MRI. We report a decline in nigro-striatal (p < .003) and dentato-pallidal (p < .0001) connectivity in the patients compared to controls, which is associated with increasing motor impairment (relating to nigro-striatal, r = -0.48; p < .001 and dentato-pallidal connectivity, r = -0.36; p = .035). Given, that variations of the ANKK1 Taq1 (rs 1,800,497) allele alters dopamine D2-dependent responses, all participants were genotyped respectively. By grouping patients (and controls) according to their ANKK1 genotype, we demonstrate a link between D2 receptor signalling and decline in connectivity in both investigated pathways for the A1- variant (nigro-striatal pathway: r = -0.53; p = .012, dentato-pallidal pathway: r = -0.62; p = .0012). In patients with the A1+ variant, we only found increased brain connectivity in the dentato-pallidal pathway (r = 0.71; p = .001) correlating with increasing motor impairment, suggesting a potentially compensatory function of the cerebellum. Related to medication response carriers of the A1+ variant had a better drug effect associated with stronger brain connectivity in the nigro-striatal pathway (r = 0.54; p < .02); the A1- group had a good medication response although nigro-striatal connectivity was diminished (r = -0.38; p < .05); these results underscore differences in receptor availability between both groups in the nigro-striatal pathway. No effect onto medication response was found in the dentato-pallidal pathway (p > .05). Interplay between basal ganglia connectivity and D2 receptor availability influence the clinical presentation and medication response of parkinsonian patients. Furthermore, while current models of basal-ganglia function emphasize that balanced activity in the direct and indirect pathways is required for normal movement, our data highlight a role of the cerebellum in compensating for physiological imbalances in this respect.

Trait anxiety and neural efficiency of abstract reasoning: An fMRI investigation

Worries preoccupy the working memory capacity in anxious individuals, thereby affecting their performance during tasks that require efficient attention regulation. According to the attentional control theory (ACT), trait anxiety affects the processing efficiency, i.e. the effort required for task performance, more than the accuracy of task performance. We investigated the relation between trait anxiety and neural response for a reasoning task in healthy subjects. Functional magnetic resonance imaging (fMRI) was carried out on 22 healthy participants and blood oxygenation level dependent (BOLD) contrast estimates were extracted from a priori regions of interest (ROIs) that were earlier implicated in reasoning (i.e., bilaterally caudate head, globus pallidus, thalamus, prefrontal cortex [[ostral, dorsal and ventral regions]] inferior parietal lobule and middle occipital gyrus). Controlling for the effects of age, gender, state anxiety and depressive symptoms, for equivalent levels of task performance, trait anxiety of the participants was found to be associated with an increase in task related BOLD activation in right globus pallidus, left thalamus and left middle occipital gyrus. Our results suggest a reduced processing efficiency for reasoning in high trait anxiety subjects and provides important brain-behaviour relationships with respect to sub-clinical anxiety.

Altered resting-state functional connectivity of the putamen and internal globus pallidus is related to speech impairment in Parkinson's disease

INTRODUCTION

Speech impairment in Parkinson's disease (PD) is pervasive, with life-impacting consequences. Yet, little is known about how functional connections between the basal ganglia and cortex relate to PD speech impairment (PDSI). Whole-brain resting-state connectivity analyses of basal ganglia nuclei can expand the understanding of PDSI pathophysiology.

METHODS

Resting-state data from 89 right-handed subjects were downloaded from the Parkinson's Progression Markers Initiative database. Subjects included 12 older healthy controls ("OHC"), 42 PD patients without speech impairment ("PDN"), and 35 PD subjects with speech impairment ("PDSI"). Subjects were assigned to PDN and PDSI groups based on the Movement Disorders Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS) Part III speech item scores ("0" vs. "1-4"). Whole-brain functional connectivity was calculated for four basal ganglia seeds in each hemisphere: putamen, caudate, external globus pallidus (GPe), and internal globus pallidus (GPi). For each seed region, group-averaged connectivity maps were compared among OHC, PDN, and PDSI groups using a multivariate ANCOVA controlling for the effects of age and sex. Subsequent planned pairwise t-tests were performed to determine differences between the three groups using a voxel-wise threshold of p < 0.001 and cluster-extent threshold of 272 mm3 (FWE<0.05).

RESULTS

In comparison with OHCs, both PDN and PDSI groups demonstrated significant differences in cortical connectivity with bilateral putamen, bilateral GPe, and right caudate. Compared to the PDN group, the PDSI subjects demonstrated significant differences in cortical connectivity with left putamen and left GPi. PDSI subjects had lower connectivity between the left putamen and left superior temporal gyrus compared to PDN. In addition, PDSI subjects had greater connectivity between left GPi and three cortical regions: left dorsal premotor/laryngeal motor cortex, left angular gyrus, and right angular gyrus.

CONCLUSIONS

The present findings suggest that speech impairment in PD is associated with altered cortical connectivity with left putamen and left GPi.

Individualized tractography-based parcellation of the globus pallidus pars interna using 7T MRI in movement disorder patients prior to DBS surgery

The success of deep brain stimulation (DBS) surgeries for the treatment of movement disorders relies on the accurate placement of an electrode within the motor portion of subcortical brain targets. However, the high number of electrodes requiring relocation indicates that today's methods do not ensure sufficient accuracy for all patients. Here, with the goal of aiding DBS targeting, we use 7 Tesla (T) MRI data to identify the functional territories and parcellate the globus pallidus pars interna (GPi) into motor, associative and limbic regions in individual subjects. 7 T MRI scans were performed in seventeen patients (prior to DBS surgery) and one healthy control. Tractography-based parcellation of each patient's GPi was performed. The cortex was divided into four masks representing motor, limbic, associative and "other" regions. Given that no direct connections between the GPi and the cortex have been shown to exist, the parcellation was carried out in two steps: 1) The thalamus was parcellated based on the cortical targets, 2) The GPi was parcellated using the thalamus parcels derived from step 1. Reproducibility, via repeated scans of a healthy subject, and validity of the findings, using different anatomical pathways for parcellation, were assessed. Lastly, post-operative imaging data was used to validate and determine the clinical relevance of the parcellation. The organization of the functional territories of the GPi observed in our individual patient population agrees with that previously reported in the literature: the motor territory was located posterolaterally, followed anteriorly by the associative region, and further antero-ventrally by the limbic territory. While this organizational pattern was observed across patients, there was considerable variability among patients. The organization of the functional territories of the GPi was remarkably reproducible in intra-subject scans. Furthermore, the organizational pattern was observed consistently by performing the parcellation of the GPi via the thalamus and via a different pathway, going through the striatum. Finally, the active therapeutic contact of the DBS electrode, identified with a combination of post-operative imaging and post-surgery DBS programming, overlapped with the high-probability "motor" region of the GPi as defined by imaging-based methods. The consistency, validity, and clinical relevance of our findings have the potential for improving DBS targeting, by increasing patient-specific knowledge of subregions of the GPi to be targeted or avoided, at the stage of surgical planning, and later, at the stage when stimulation is adjusted.

Changes in Signal Intensity of the Dentate Nucleus and Globus Pallidus in Pediatric Patients: Impact of Brain Irradiation and Presence of Primary Brain Tumors Independent of Linear Gadolinium-based Contrast Agent Administration

Purpose To determine whether whole-brain irradiation, chemotherapy, and primary brain pathologic conditions affect magnetic resonance (MR) imaging signal changes in pediatric patients independent of the administration of gadolinium-based contrast agents (GBCAs). Materials and Methods This institutional review board-approved, HIPAA-compliant study included 144 pediatric patients who underwent intravenous GBCA-enhanced MR imaging examinations (55 patients with primary brain tumors and whole-brain irradiation, 19 with primary brain tumors and chemotherapy only, 52 with primary brain tumors without any treatment, and 18 with neuroblastoma without brain metastatic disease). The signal intensities (SIs) in the globus pallidus (GP), thalamus (T), dentate nucleus (DN), and pons (P) were measured on unenhanced T1-weighted images. GP:T and DN:P SI ratios were compared between groups by using the analysis of variance and were analyzed relative to group, total cumulative number of doses of GBCA, age, and sex by using multivariable linear models. Results DN:P ratio for the radiation therapy group was greater than that for the other groups except for the group of brain tumors treated with chemotherapy (P < .05). The number of GBCA doses was correlated with the DN:P ratio for the nontreated brain tumor group (P < .0001). The radiation therapy-treated brain tumor group demonstrated higher DN:P ratios than the nontreated brain tumor group for number of doses less than or equal to 10 (P < .0001), whereas ratios in the nontreated brain tumor group were higher than those in the radiation therapy-treated brain tumor group for doses greater than 20 (P = .05). The GP:T ratios for the brain tumor groups were greater than that for the neuroblastoma group (P = .01). Conclusion Changes in SI of the DN and GP that are independent of the administration of GBCA occur in patients with brain tumors undergoing brain irradiation, as well as in patients with untreated primary brain tumors. © RSNA, 2017.

Does renal function affect gadolinium deposition in the brain?

OBJECTIVE

Was to compare T1 signal intensity ratios of dentate nucleus to cerebellar white matter (DN/cerebellum), dentate nucleus to pons (DN/pons) and globus pallidus to thalamus (GP/thalamus) in patients with normal renal function and in patients on chronic hemodialysis. To find out if renal function affects the deposition of gadolinium in brain after administration of linear gadolinium based contrast agents (GBCA).

METHODS

Seventy eight contrast enhanced brain MRIs (Magnetic Resonance Imaging) with linear GBCA of 13 patients on chronic hemodialysis and 13 patients with normal renal function retrospectively evaluated. The DN/pons, DN/cerebellum and GP/thalamus signal intensity ratios were measured from each brain MRI on unenhanced axial T1 weighted images.

RESULTS

In hemodialysis group statistically significant increase in the signal intensity ratios of DN/pons, DN/cerebellum and GP/thalamus were found between the first and the last brain MRIs (p = .001). The increase in the signal intensity ratios of DN/pons, DN/cerebellum and GP/thalamus between the first and the last brain MRIs in control group were not significant (p > 0.05). The signal intensity increase in DN and globus pallidus were significantly higher in hemodialysis group than control group (p < 0.05).

CONCLUSIONS

Patients on hemodialysis had significantly higher DN and GP signal intensity increase compared to the patients with normal renal function. Renal function affects the rate of gadolinium deposition in the brain after administration of linear GBCA.

Kernicterus with abnormal high-signal changes bilaterally in the globus pallidus: A case report

Kernicterus is a relatively rare consequence of hyperbilirubinemia. There is an important role for MRI imaging for this entity in the appropriate clinical context as there are distinct signal changes in the globus pallidus. A case report and image findings are presented

Reduced subcortical volumes among preschool-age girls and boys with ADHD

Anomalous brain structure and function are implicated in children with attention-deficit/hyperactivity disorder (ADHD). Most neuroimaging research, however, has examined school-aged children, despite the typical onset of symptoms in early childhood. This study compared the volumes of subcortical structures (caudate nucleus, putamen, globus pallidus, and thalamus) among preschoolers with ADHD and typically developing (TD) children. High resolution T1-weighted 3D MPRAGE images covering the whole brain were acquired on a 3T scanner and subcortical volumes were automatically extracted. Analyses were conducted in a total of 87 medication-naïve preschoolers, ages 4-5 years (47 with ADHD, 40 controls; 63% boys). ADHD was diagnosed using modified DSM-IV criteria based on review of developmental history, structured psychiatric interview and caregiver ratings. Compared to typically developing children, subcortical volumes were reduced among preschoolers with ADHD, with largest reductions in the caudate, globus pallidus, and thalamus. Among girls (but not boys) with ADHD, putamen and thalamus volumes were associated with ADHD symptom severity. The observed patterns of subcortical differences in preschoolers with ADHD (larger reductions in girls), contrasted with differences observed among school-aged children, (larger reductions in boys) suggests that children with ADHD show sexual dimorphism in neuroanatomical development that parallels early trajectory of symptom onset and attenuation.

"Eye of the Tiger" in a Non-Responsive Neuropsychiatric Patient: A Case Report

Hallervorden-Spatz syndrome is a rare neurodegenerative disorder with hereditary properties. It usually occurs in young adolescents with extrapyramidal symptoms besides disturbed mental function. In this study, we present a 23-year-old neuropsychiatric patient who primarily misdiagnosed to have conversion disorder. She had 5-year history of progressive dysarthria and generalized abnormal movements. After detecting the pathognomonic sign of "eye of the tiger" diagnosis was confirmed. The patient was discharged. She had satisfactory condition in her follow-up. Such a rare syndrome should be considered in patients with similar presentation, and upon the diagnosis, PKAN2 gene study should be done to detect possible new mutations.

Up to 52 administrations of macrocyclic ionic MR contrast agent are not associated with intracranial gadolinium deposition: Multifactorial analysis in 385 patients

PURPOSE

To determine whether multiple repeated administrations of gadolinium-based macrocyclic ionic MR contrast agent (MICA) are associated with intracranial gadolinium deposition and identify the predisposing factors for deposition in various clinical situations.

MATERIALS AND METHODS

In this institutional review board-approved retrospective study, 385 consecutive patients who underwent MICA-enhanced MR imaging were enrolled. The dentate nucleus-to-pons (DN/P) and globus pallidus-to-thalamus (GP/Th) signal intensity (SI) ratios on unenhanced T1-weighted images were recorded by 2 independent readers and averaged. The mean DN/P and GP/Th SI ratio difference between the last and the first examinations were tested using the one-sample t-test. Student's t-test and stepwise regression analysis were used to identify the predisposing factors for deposition based on the number of administrations, time interval, hepatic and renal function, magnetic field strength, and chemo- or radiation therapy.

RESULTS

The mean DN/P SI ratio difference was not different from zero (P = .697), even in patients with ≥20 administrations (n = 33). Only patients with abnormal renal function showed an increase in the mean DN/P SI ratio difference (P = .019). The mean DN/P SI ratio difference was not associated with any predisposing factors. However, the mean GP/Th SI ratio difference showed decrease (P < .001), which was associated with age (P = .007), number of administrations (P = .01) and number of radiation therapy sessions (P = .022) on multivariate analysis.

CONCLUSION

Multiple repeated administrations of MICA were not associated with increased T1 signal intensity in deep brain nuclei suggestive of Gd deposition in patients with normal renal function.

Intractable Blepharospasm Treated with Bilateral Pallidal Deep Brain Stimulation

BACKGROUND

Blepharospasm can be present as an isolated dystonia or in conjunction with other forms of cranial dystonia, causing significant disability.

CASE REPORT

We report a case of a 69-year-old male with craniocervical dystonia, manifesting primarily as incapacitating blepharospasm refractory to medical treatments. He underwent bilateral globus pallidus (GP) deep brain stimulation (DBS) with complete resolution of his blepharospasm and sustained benefit at 12 months postoperatively.

DISCUSSION

This case illustrates successful treatment of blepharospasm with pallidal stimulation. GP-DBS should be considered a reasonable therapeutic option for intractable blepharospasm.