Abstract 14655: Diffusion Neuroimaging of Adults With D-Transposition of the Great Arteries Reveal White Matter Alterations in the Connectomic Rich Club

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Ai Wern Chung ◽  
Borjan Gagoski ◽  
Jane W Newburger ◽  
P. Ellen Grant ◽  
Michelle GURVITZ
Keyword(s):  
White Matter ◽  
Structural Integrity ◽  
Circulatory Arrest ◽  
A Priori ◽  
Group Differences ◽  
High Angular Resolution ◽  
Central System ◽  
Rich Club ◽  
Apparent Diffusion ◽  
Cortical Regions

Introduction: The population of adults with d-transposition of the great arteries (TGA) continue to grow. As this group has underlying neurocognitive impairment and longer-term neurovascular damage, advanced neuroimaging to identify markers for treatment is required. Diffusion (d)MRI tractography quantifies the structural integrity of white matter (WM) pathways in the brain - where lower FA (fractional anisotropy) and higher ADC (apparent diffusion coefficient) typify WM damage. The brain’s structural backbone is its rich club (RC), a set of highly interconnected regions established before birth and vital for effective cognitive function. Moreover, there are Feeder and Seeder subnetworks peripheral to the RC, which are thought to form later and may be more adaptive. Hypothesis: We hypothesize that adults with TGA have alterations in both the brain’s structural RC and in peripheral connections. Methods: Subjects were TGA adults from the Boston Circulatory Arrest Study (n = 25, mean age 28.46 ± 1.14yr) and Controls (n = 13, 28.35 ± 1.70). Multi-shell, high-angular resolution dMRI data were acquired and fitted with a multi-fiber model (Fig). After tractography, a connectome of the number of tracts connecting pairwise cortical regions was computed. A priori RC regions were bilateral superior frontal and parietal frontal gyri, precuneus, posterior cingulate and insular regions. Connections were grouped into subnetworks and mean FA and ADC computed. Results: Cohorts were age-matched (p=0.801, unpaired t-test). Overall, patients had lower FA and greater ADC than controls in all subnetworks. Group differences (unpaired t-tests) were significant in the RC (ADC p=0.029), Feeder subnetwork (FA p=0.041; ADC p=0.042), with trends in Seeder subnetworks (FA p=0.061; ADC p=0.062). Conclusions: Widespread WM alterations exist in adults with TGA not only in the brain’s most central system, but also connections feeding into the RC suggesting prenatal and adaptive changes.

scholarly journals Grey matter microstructural differences in developmental stuttering

2021 ◽  
Author(s):  
Gabriel Cler ◽  
Saloni Krishnan ◽  
Daniel Papp ◽  
Charlie E E Wiltshire ◽  
Jennifer Chesters ◽  
...  
Keyword(s):  
White Matter ◽  
Brain Tissue ◽  
Grey Matter ◽  
Group Differences ◽  
Significant Group ◽  
Conventional Mri ◽  
Cortical Motor ◽  
Cortical Regions ◽  
Developmental Stuttering ◽  
New Evidence

Theoretical accounts of developmental stuttering implicate dysfunctional cortico-striatal-thalamo-cortical motor loops through the putamen, but empirical evidence of these proposed differences is currently limited. Conventional MRI data has been used in people who stutter to measure the size or volume of grey matter structures, cortical thickness, and diffusion properties of white matter fibre tracts. Quantitative mapping of brain tissue can reveal detailed maps of microstructural properties of brain tissue in both grey and white matter, but has not yet been assessed in people who stutter. Analysis of these quantitative maps in 41 people who stutter and 32 matched controls revealed significant group differences in maps of R2*, indicative of higher iron content in people who stutter than controls in left cortical regions important for speech motor control and the left putamen. Higher iron levels in brain tissue in people who stutter may be a marker of elevated dopamine levels or lysosomal dysfunction. This study represents the first use of these quantitative measures in developmental stuttering and provides new evidence of structural differences.

Individual differences in white and grey matter structure associated with verbal habits of thought

2019 ◽  
Author(s):  
Justin C. Hayes ◽  
Katherine L Alfred ◽  
Rachel Pizzie ◽  
Joshua S. Cetron ◽  
David J. M. Kraemer
Keyword(s):  
Individual Differences ◽  
White Matter ◽  
Cognitive Processing ◽  
Grey Matter ◽  
Structural Changes ◽  
Structural Integrity ◽  
Diffusion Tensor ◽  
Self Report ◽  
White Matter Tracts

Modality specific encoding habits account for a significant portion of individual differences reflected in functional activation during cognitive processing. Yet, little is known about how these habits of thought influence long-term structural changes in the brain. Traditionally, habits of thought have been assessed using self-report questionnaires such as the visualizer-verbalizer questionnaire. Here, rather than relying on subjective reports, we measured habits of thought using a novel behavioral task assessing attentional biases toward picture and word stimuli. Hypothesizing that verbal habits of thought are reflected in the structural integrity of white matter tracts and cortical regions of interest, we used diffusion tensor imaging and volumetric analyses to assess this prediction. Using a whole-brain approach, we show that word bias is associated with increased volume in several bilateral language regions, in both white and grey matter parcels. Additionally, connectivity within white matter tracts within an a priori speech production network increased as a function of word bias. These results demonstrate long-term structural and morphological differences associated with verbal habits of thought.

scholarly journals Impaired Cerebrovascular Hemodynamics are Associated with Cerebral White Matter Damage

2013 ◽  
Vol 34 (2) ◽  
pp. 228-234 ◽  
Author(s):  
Sushmita Purkayastha ◽  
Otite Fadar ◽  
Aujan Mehregan ◽  
David H Salat ◽  
Nicola Moscufo ◽  
...  
Keyword(s):  
White Matter ◽  
Middle Cerebral Artery ◽  
Cerebral Artery ◽  
Cerebral Autoregulation ◽  
Structural Integrity ◽  
Cerebral White Matter ◽  
Elderly Individuals ◽  
Transfer Function Analysis ◽  
Dynamic Cerebral Autoregulation ◽  
Cerebrovascular Hemodynamics

White matter hyperintensities (WMH) in elderly individuals with vascular diseases are presumed to be due to ischemic small vessel diseases; however, their etiology is unknown. We examined the cross-sectional relationship between cerebrovascular hemodynamics and white matter structural integrity in elderly individuals with vascular risk factors. White matter hyperintensity volumes, fractional anisotropy (FA), and mean diffusivity (MD) were obtained from MRI in 48 subjects (75±7years). Pulsatility index (PI) and dynamic cerebral autoregulation (dCA) was assessed using transcranial Doppler ultrasound of the middle cerebral artery. Dynamic cerebral autoregulation was calculated from transfer function analysis (phase and gain) of spontaneous blood pressure and flow velocity oscillations in the low (LF, 0.03 to 0.15 Hz) and high (HF, 0.16 to 0.5 Hz) frequency ranges. Higher PI was associated with greater WMH ( P<0.005). Higher phase across all frequency ranges was associated with greater FA and lower MD ( P<0.005). Lower gain was associated with higher FA in the LF range ( P=0.001). These relationships between phase and FA were significant in the territories limited to the middle cerebral artery as well as across the entire brain. Our results show a strong relationship between impaired cerebrovascular hemodynamics (PI and dCA) and loss of cerebral white matter structural integrity (WMH and DTI metrics) in elderly individuals.

scholarly journals MR Detection of Cortical Spreading Depression Immediately after Focal Ischemia in the Rat

1996 ◽  
Vol 16 (2) ◽  
pp. 214-220 ◽  
Author(s):  
Joachim Röther ◽  
Alexander J. de Crespigny ◽  
Helen D'Arceuil ◽  
Michael E. Moseley
Keyword(s):  
Cortical Spreading Depression ◽  
Spreading Depression ◽  
Tissue Perfusion ◽  
Artery Occlusion ◽  
Acute Ischemia ◽  
Planar Imaging ◽  
Mr Perfusion Imaging ◽  
Before And After ◽  
Apparent Diffusion ◽  
Cortical Regions

The suture model for middle cerebral artery occlusion (MCAO) was used to induce acute ischemia in rats remotely within a magnetic resonance (MRI) scanner. Serial MR diffusion weighted imaging (DWI) was performed during remote MCAO using an echo planar imaging technique. MR perfusion imaging was performed before and after occlusion using the bolus tracking technique. Transient apparent diffusion coefficient (ADC) changes were detected in six of seven rats as early as 2.7 ± 1.5 min post MCAO. ADC values declined transiently to 70.1 ± 6.0% of control and recovered to 95.5 ± 6.8% of control within 3.3 ± 2.9 min. These ADC changes propagated bidirectionally away from the ischemic core with a speed of 3.0 ± 1.1 mm/min. Transient ADC decreases only occurred in ischemic areas characterized by moderately decreased tissue perfusion. Propagation toward cortical regions with severe tissue perfusion deficits was not detected. DWI can detect the earliest dynamic, reversible ADC changes in the ischemic tissue. The speed of propagation of the decreasing ADC wave, the waveform characteristics, and the occurrence in moderately perturbated tissue are compatible with cortical spreading depression.

scholarly journals Q -ball imaging of macaque white matter architecture

2005 ◽  
Vol 360 (1457) ◽  
pp. 869-879 ◽  
Author(s):  
David S Tuch ◽  
Jonathan J Wisco ◽  
Mark H Khachaturian ◽  
Leeland B Ekstrom ◽  
Rolf Kötter ◽  
...  
Keyword(s):  
White Matter ◽  
Magnetic Resonance ◽  
Diffusion Imaging ◽  
Large Body ◽  
Macaque Monkey ◽  
High Angular Resolution ◽  
Imaging Method ◽  
Diffusion Tractography ◽  
Axonal Projections ◽  
Histological Validation

Diffusion-weighted magnetic resonance imaging holds substantial promise as a technique for non-invasive imaging of white matter (WM) axonal projections. For diffusion imaging to be capable of providing new insight into the connectional neuroanatomy of the human brain, it will be necessary to histologically validate the technique against established tracer methods such as horseradish peroxidase and biocytin histochemistry. The macaque monkey provides an ideal model for histological validation of the diffusion imaging method due to the phylogenetic proximity between humans and macaques, the gyrencephalic structure of the macaque cortex, the large body of knowledge on the neuroanatomic connectivity of the macaque brain and the ability to use comparable magnetic resonance acquisition protocols in both species. Recently, it has been shown that high angular resolution diffusion imaging (HARDI) can resolve multiple axon orientations within an individual imaging voxel in human WM. This capability promises to boost the accuracy of tract reconstructions from diffusion imaging. If the macaque is to serve as a model for histological validation of the diffusion tractography method, it will be necessary to show that HARDI can also resolve intravoxel architecture in macaque WM. The present study therefore sought to test whether the technique can resolve intravoxel structure in macaque WM. Using a HARDI method called q -ball imaging (QBI) it was possible to resolve composite intravoxel architecture in a number of anatomic regions. QBI resolved intravoxel structure in, for example, the dorsolateral convexity, the pontine decussation, the pulvinar and temporal subcortical WM. The paper concludes by reviewing remaining challenges for the diffusion tractography project.

scholarly journals Organization of cortico-cortical pathways supporting memory retrieval across subregions of the left ventrolateral prefrontal cortex

2016 ◽  
Vol 116 (3) ◽  
pp. 920-937 ◽  
Author(s):  
Jennifer Barredo ◽  
Timothy D. Verstynen ◽  
David Badre
Keyword(s):  
Prefrontal Cortex ◽  
White Matter ◽  
Functional Connectivity ◽  
Memory Retrieval ◽  
Temporal Cortex ◽  
Functional Network ◽  
High Angular Resolution ◽  
Connectivity Analysis ◽  
Ventrolateral Prefrontal Cortex ◽  
Functional Connectivity Analysis

Functional magnetic resonance imaging (fMRI) evidence indicates that different subregions of ventrolateral prefrontal cortex (VLPFC) participate in distinct cortical networks. These networks have been shown to support separable cognitive functions: anterior VLPFC [inferior frontal gyrus (IFG) pars orbitalis] functionally correlates with a ventral fronto-temporal network associated with top-down influences on memory retrieval, while mid-VLPFC (IFG pars triangularis) functionally correlates with a dorsal fronto-parietal network associated with postretrieval control processes. However, it is not known to what extent subregional differences in network affiliation and function are driven by differences in the organization of underlying white matter pathways. We used high-angular-resolution diffusion spectrum imaging and functional connectivity analysis in unanesthetized humans to address whether the organization of white matter connectivity differs between subregions of VLPFC. Our results demonstrate a ventral-dorsal division within IFG. Ventral IFG as a whole connects broadly to lateral temporal cortex. Although several different individual white matter tracts form connections between ventral IFG and lateral temporal cortex, functional connectivity analysis of fMRI data indicates that these are part of the same ventral functional network. By contrast, across subdivisions, dorsal IFG was connected with the midfrontal gyrus and correlated as a separate dorsal functional network. These qualitative differences in white matter organization within larger macroanatomical subregions of VLPFC support prior functional distinctions among these regions observed in task-based and functional connectivity fMRI studies. These results are consistent with the proposal that anatomical connectivity is a crucial determinant of systems-level functional organization of frontal cortex and the brain in general.

scholarly journals Structural disconnectivity in schizophrenia: a diffusion tensor magnetic resonance imaging study

2003 ◽  
Vol 182 (5) ◽  
pp. 439-443 ◽  
Author(s):  
J. Burns ◽  
D. Job ◽  
M. E. Bastin ◽  
H. Whalley ◽  
T. Macgillivray ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
White Matter ◽  
Magnetic Resonance ◽  
Fractional Anisotropy ◽  
Structural Integrity ◽  
Diffusion Tensor ◽  
Uncinate Fasciculus ◽  
Arcuate Fasciculus ◽  
Resonance Imaging ◽  
White Matter Tracts

BackgroundThere is growing evidence that schizophrenia is a disorder of cortical connectivity Specifically, frontotemporal and frontoparietal connections are thought to be functionally impaired. Diffusion tensor magnetic resonance imaging (DT–MRI) is a technique that has the potential to demonstrate structural disconnectivity in schizophrenia.AimsTo investigate the structural integrity of frontotemporal and frontoparietal white matter tracts in schizophrenia.MethodThirty patients with DSM–IV schizophrenia and thirty matched control subjects underwent DT–MRI and structural MRI. Fractional anisotropy – an index of the integrity of white matter tracts – was determined in the uncinate fasciculus, the anterior cingulum and the arcuate fasciculus and analysed using voxel-based morphometry.ResultsThere was reduced fractional anisotropy in the left uncinate fasciculus and left arcuate fasciculus in patients with schizophrenia compared with controls.ConclusionsThe findings of reduced white matter tract integrity in the left uncinate fasciculus and left arcuate fasciculus suggest that there is frontotemporal and frontoparietal structural disconnectivity in schizophrenia.

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