1
|
Olm CA, McMillan CT, Irwin DJ, Van Deerlin VM, Cook PA, Gee JC, Grossman M. Longitudinal structural gray matter and white matter MRI changes in presymptomatic progranulin mutation carriers. Neuroimage Clin 2018; 19:497-506. [PMID: 29984158 PMCID: PMC6029561 DOI: 10.1016/j.nicl.2018.05.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Revised: 03/29/2018] [Accepted: 05/13/2018] [Indexed: 11/21/2022]
Abstract
Introduction Mutations in the progranulin (GRN) gene are a major source of inherited frontotemporal degeneration (FTD) spectrum disorders associated with TDP-43 proteinopathy. We use structural MRI to identify regions of baseline differences and longitudinal changes in gray matter (GM) and white matter (WM) in presymptomatic GRN mutation carriers (pGRN+) compared to young controls (yCTL). Methods Cognitively intact first-degree relatives of symptomatic GRN+ FTD patients with identified GRN mutations (pGRN+; N = 11, mean age = 41.4) and matched yCTL (N = 11, mean age = 53.6) were identified. They completed a MRI session with T1-weighted imaging to assess GM density (GMD) and diffusion-weighted imaging (DWI) to assess fractional anisotropy (FA). Participants completed a follow-up session with T1 and DWI imaging (pGRN+ mean interval 2.20 years; yCTL mean interval 3.27 years). Annualized changes of GMD and FA were also compared. Results Relative to yCTL, pGRN+ individuals displayed reduced GMD at baseline in bilateral orbitofrontal, insular, and anterior temporal cortices. pGRN+ also showed greater annualized GMD changes than yCTL at follow-up in right orbitofrontal and left occipital cortices. We also observed reduced FA at baseline in bilateral superior longitudinal fasciculus, left corticospinal tract, and frontal corpus callosum in pGRN+ relative to yCTL, and pGRN+ displayed greater annualized longitudinal FA change in right superior longitudinal fasciculus and frontal corpus callosum. Conclusions Longitudinal MRI provides evidence of progressive GM and WM changes in pGRN+ participants relative to yCTL. Structural MRI illustrates the natural history of presymptomatic GRN carriers, and may provide an endpoint during disease-modifying treatment trials for pGRN+ individuals at risk for FTD.
Collapse
Key Words
- AD, axial diffusivity
- BA, Brodmann area
- CST, corticospinal tract
- DWI, diffusion-weighted imaging
- FA, fractional anisotropy
- FTD, frontotemporal degeneration
- Frontotemporal lobar degeneration
- GM, gray matter
- GMD, gray matter density
- GRN+, symptomatic progranulin mutation carriers
- GRN, progranulin
- IFO, inferior fronto-occipital fasciculus
- ILF, inferior longitudinal fasciculus
- Longitudinal
- MD, mean diffusivity
- Magnetic resonance imaging
- Neuroimaging
- Presymptomatic
- Progranulin
- RD, radial diffusivity
- ROI, region of interest
- SLF, superior longitudinal fasciculus
- WM, white matter
- eCTL, elderly healthy controls
- pGRN+, presymptomatic progranulin mutation carriers
- yCTL, young healthy controls
Collapse
Affiliation(s)
- Christopher A Olm
- Penn Frontotemporal Degeneration Center, Department of Neurology, University of Pennsylvania, Philadelphia, PA, United States; Penn Image Computing and Science Laboratory, Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States
| | - Corey T McMillan
- Penn Frontotemporal Degeneration Center, Department of Neurology, University of Pennsylvania, Philadelphia, PA, United States
| | - David J Irwin
- Penn Frontotemporal Degeneration Center, Department of Neurology, University of Pennsylvania, Philadelphia, PA, United States; Center for Neurodegenerative Disease Research, Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Vivianna M Van Deerlin
- Center for Neurodegenerative Disease Research, Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Philip A Cook
- Penn Image Computing and Science Laboratory, Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States
| | - James C Gee
- Penn Image Computing and Science Laboratory, Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States
| | - Murray Grossman
- Penn Frontotemporal Degeneration Center, Department of Neurology, University of Pennsylvania, Philadelphia, PA, United States.
| |
Collapse
|
2
|
Gajamange S, Raffelt D, Dhollander T, Lui E, van der Walt A, Kilpatrick T, Fielding J, Connelly A, Kolbe S. Fibre-specific white matter changes in multiple sclerosis patients with optic neuritis. Neuroimage Clin 2017. [PMID: 29527473 PMCID: PMC5842545 DOI: 10.1016/j.nicl.2017.09.027] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Long term irreversible disability in multiple sclerosis (MS) is thought to be primarily driven by axonal degeneration. Axonal degeneration leads to degenerative atrophy, therefore early markers of axonal degeneration are required to predict clinical disability and treatment efficacy. Given that additional pathologies such as inflammation, demyelination and oedema are also present in MS, it is essential to develop axonal markers that are not confounded by these processes. The present study investigated a novel method for measuring axonal degeneration in MS based on high angular resolution diffusion magnetic resonance imaging. Unlike standard methods, this novel method involved advanced acquisition and modelling for improved axonal sensitivity and specificity. Recent work has developed analytical methods, two novel axonal markers, fibre density and cross-section, that can be estimated for each fibre direction in each voxel (termed a “fixel”). This technique, termed fixel-based analysis, thus simultaneously estimates axonal density and white matter atrophy from specific white matter tracts. Diffusion-weighted imaging datasets were acquired for 17 patients with a history of acute unilateral optic neuritis (35.3 ± 10.2 years, 11 females) and 14 healthy controls (32.7 ± 4.8 years, 8 females) on a 3 T scanner. Fibre density values were compared to standard diffusion tensor imaging parameters (fractional anisotropy and mean diffusivity) in lesions and normal appearing white matter. Group comparisons were performed for each fixel to assess putative differences in fibre density and fibre cross-section. Fibre density was observed to have a comparable sensitivity to fractional anisotropy for detecting white matter pathology in MS, but was not affected by crossing axonal fibres. Whole brain fixel-based analysis revealed significant reductions in fibre density and fibre cross-section in the inferior fronto-occipital fasciculus (including the optic radiations) of patients compared to controls. We interpret this result to indicate that this fixel-based approach is able to detect early loss of fibre density and cross-section in the optic radiations in MS patients with a history of optic neuritis. Fibre-specific markers of axonal degeneration should be investigated further for use in early stage therapeutic trials, or to monitor axonal injury in early stage MS. Fibre density is reduced in lesions and normal-appearing white matter in MS Fibre density detects white matter pathology in regions of crossing fibres Loss of fibre density and cross-section selectively evident in visual pathways of optic neuritis patients.
Collapse
Affiliation(s)
- Sanuji Gajamange
- Department of Anatomy and Neuroscience, University of Melbourne, Australia
| | - David Raffelt
- The Florey Institute of Neuroscience and Mental Health, Melbourne, Australia
| | - Thijs Dhollander
- The Florey Institute of Neuroscience and Mental Health, Melbourne, Australia
| | - Elaine Lui
- Department of Radiology, Royal Melbourne Hospital, University of Melbourne, Australia
| | | | - Trevor Kilpatrick
- Department of Anatomy and Neuroscience, University of Melbourne, Australia
| | - Joanne Fielding
- School of Psychological Sciences, Monash University, Australia
| | - Alan Connelly
- The Florey Institute of Neuroscience and Mental Health, Melbourne, Australia; The Florey Department of Neuroscience and Mental Health, University of Melbourne, Australia
| | - Scott Kolbe
- Department of Anatomy and Neuroscience, University of Melbourne, Australia; The Florey Institute of Neuroscience and Mental Health, Melbourne, Australia.
| |
Collapse
|
3
|
Canu E, Agosta F, Mandic-Stojmenovic G, Stojković T, Stefanova E, Inuggi A, Imperiale F, Copetti M, Kostic VS, Filippi M. Multiparametric MRI to distinguish early onset Alzheimer's disease and behavioural variant of frontotemporal dementia. Neuroimage Clin 2017; 15:428-438. [PMID: 28616383 PMCID: PMC5458769 DOI: 10.1016/j.nicl.2017.05.018] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Revised: 05/12/2017] [Accepted: 05/25/2017] [Indexed: 12/11/2022]
Abstract
This prospective study explored whether an approach combining structural [cortical thickness and white matter (WM) microstructure] and resting state functional MRI can aid differentiation between 62 early onset Alzheimer's disease (EOAD) and 27 behavioural variant of frontotemporal dementia (bvFTD) patients. Random forest and receiver operator characteristic curve analyses assessed the ability of MRI in classifying the two clinical syndromes. All patients showed a distributed pattern of brain alterations relative to controls. Compared to bvFTD, EOAD patients showed bilateral inferior parietal cortical thinning and decreased default mode network functional connectivity. Compared to EOAD, bvFTD patients showed bilateral orbitofrontal and temporal cortical thinning, and WM damage of the corpus callosum, bilateral uncinate fasciculus, and left superior longitudinal fasciculus. Random forest analysis revealed that left inferior parietal cortical thickness (accuracy 0.78, specificity 0.76, sensitivity 0.83) and WM integrity of the right uncinate fasciculus (accuracy 0.81, specificity 0.96, sensitivity 0.43) were the best predictors of clinical diagnosis. The combination of cortical thickness and DT MRI measures was able to distinguish patients with EOAD and bvFTD with accuracy 0.82, specificity 0.76, and sensitivity 0.96. The diagnostic ability of MRI models was confirmed in a subsample of patients with biomarker-based clinical diagnosis. Multiparametric MRI is useful to identify brain alterations which are specific to EOAD and bvFTD. A severe cortical involvement is suggestive of EOAD, while a prominent WM damage is indicative of bvFTD. Multimodal MRI distinguishes in vivo EOAD and bvFTD patients EOAD and bvFTD show a distributed pattern of structural brain alterations A severe cortical involvement is suggestive of EOAD relative to bvFTD A prominent WM damage is indicative of bvFTD relative to EOAD
Collapse
Key Words
- ACE-R, Addenbrooke's Cognitive Examination-revised
- Behavioural variant of frontotemporal dementia
- CC, corpus callosum
- CSF, cerebrospinal fluid
- Cortical thickness
- DMN, default mode network
- DT, diffusion tensor
- Diagnosis
- EOAD, early onset Alzheimer's disease
- Early onset Alzheimer's disease
- GM, grey matter
- IC, independent component
- ILF, inferior longitudinal fasciculus
- LOAD, late onset Alzheimer's disease
- MNI, Montreal Neurological Institute
- NVI, Normalized Variable Importance
- RS fMRI, resting state functional MRI
- RSN, resting state network
- Resting state functional MRI
- SLF, superior longitudinal fasciculus
- TFCE, threshold-free cluster enhancement
- WM, white matter
- White matter (WM) damage
- bvFTD, behavioural variant frontotemporal dementia
Collapse
Affiliation(s)
- Elisa Canu
- Neuroimaging Research Unit, Institute of Experimental Neurology, Division of Neuroscience, San Raffaele Scientific Institute, via Olgettina 60, 20132 Milan, Italy
| | - Federica Agosta
- Neuroimaging Research Unit, Institute of Experimental Neurology, Division of Neuroscience, San Raffaele Scientific Institute, via Olgettina 60, 20132 Milan, Italy
| | - Gorana Mandic-Stojmenovic
- Neuroimaging Research Unit, Institute of Experimental Neurology, Division of Neuroscience, San Raffaele Scientific Institute, via Olgettina 60, 20132 Milan, Italy; Clinic of Neurology, Faculty of Medicine, University of Belgrade, Dr Subotića 6, PO Box 12, 11129 Belgrade 102, Serbia
| | - Tanja Stojković
- Clinic of Neurology, Faculty of Medicine, University of Belgrade, Dr Subotića 6, PO Box 12, 11129 Belgrade 102, Serbia
| | - Elka Stefanova
- Clinic of Neurology, Faculty of Medicine, University of Belgrade, Dr Subotića 6, PO Box 12, 11129 Belgrade 102, Serbia
| | - Alberto Inuggi
- Unit of Robotics, Brain and Cognitive Sciences, Istituto Italiano di Tecnologia, Via Morego, 30, 16163 Genoa, Italy
| | - Francesca Imperiale
- Neuroimaging Research Unit, Institute of Experimental Neurology, Division of Neuroscience, San Raffaele Scientific Institute, via Olgettina 60, 20132 Milan, Italy
| | - Massimiliano Copetti
- Biostatistics Unit, IRCCS-Ospedale Casa Sollievo della Sofferenza, Viale Cappuccini, San Giovanni Rotondo, 71013 Foggia, Italy
| | - Vladimir S Kostic
- Clinic of Neurology, Faculty of Medicine, University of Belgrade, Dr Subotića 6, PO Box 12, 11129 Belgrade 102, Serbia
| | - Massimo Filippi
- Neuroimaging Research Unit, Institute of Experimental Neurology, Division of Neuroscience, San Raffaele Scientific Institute, via Olgettina 60, 20132 Milan, Italy; Department of Neurology, Institute of Experimental Neurology, Division of Neuroscience, San Raffaele Scientific Institute, via Olgettina 60, 20132 Milan, Italy.
| |
Collapse
|
4
|
Waller R, Dotterer HL, Murray L, Maxwell AM, Hyde LW. White-matter tract abnormalities and antisocial behavior: A systematic review of diffusion tensor imaging studies across development. Neuroimage Clin 2017; 14:201-15. [PMID: 28180079 DOI: 10.1016/j.nicl.2017.01.014] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 12/20/2016] [Accepted: 01/15/2017] [Indexed: 01/09/2023]
Abstract
Antisocial behavior (AB), including aggression, violence, and theft, is thought be underpinned by abnormal functioning in networks of the brain critical to emotion processing, behavioral control, and reward-related learning. To better understand the abnormal functioning of these networks, research has begun to investigate the structural connections between brain regions implicated in AB using diffusion tensor imaging (DTI), which assesses white-matter tract microstructure. This systematic review integrates findings from 22 studies that examined the relationship between white-matter microstructure and AB across development. In contrast to a prior hypothesis that AB is associated with greater diffusivity specifically in the uncinate fasciculus, findings suggest that adult AB is associated with greater diffusivity across a range of white-matter tracts, including the uncinate fasciculus, inferior fronto-occipital fasciculus, cingulum, corticospinal tract, thalamic radiations, and corpus callosum. The pattern of findings among youth studies was inconclusive with both higher and lower diffusivity found across association, commissural, and projection and thalamic tracts. Antisocial behavior (AB) is characterized by impaired emotion and reward processing. These behaviors may develop from microstructural abnormalities of white-matter tracts. We provide a systematic review of 22 diffusion tensor imaging studies of AB. Adult AB was linked to greater diffusivity (“poorer integrity”) across a range of white-matter tracts. For youth AB, there were mixed findings.
Collapse
Key Words
- AB, antisocial behavior
- AD, axial diffusivity
- APD, antisocial personality disorder
- Antisocial behavior
- CD, conduct disorder
- CU, callous-unemotional
- Callous-unemotional traits
- DMN, default mode network
- DTI, diffusion tensor imaging
- Diffusion tensor imaging
- FA, fractional anisotropy
- IFOF, inferior fronto-occipital fasciculus
- ILF, inferior longitudinal fasciculus
- MD, mean diffusivity
- Neuroimaging
- Psychopathy
- RD, radial diffusivity
- SLF, superior longitudinal fasciculus
- Systematic review
- UF, uncinate fasciculus
Collapse
|
5
|
Asaf A, Evan S, Anat A. Injury to white matter tracts in relapsing-remitting multiple sclerosis: A possible therapeutic window within the first 5 years from onset using diffusion-tensor imaging tract-based spatial statistics. Neuroimage Clin 2015; 8:261-6. [PMID: 26106550 PMCID: PMC4474176 DOI: 10.1016/j.nicl.2015.04.020] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/22/2015] [Revised: 04/15/2015] [Accepted: 04/28/2015] [Indexed: 11/23/2022]
Abstract
DTI studies in multiple sclerosis (MS) reveal white matter (WM) injury that occurs with disease progression. In the present study we aimed to elucidate the relationship of microstructural WM damage in patients with varying periods of disease duration. DTI scans were acquired from 90 MS patients and 25 healthy controls. Patients were grouped to short (<1 year), moderate (1 up to 6 years) and long (6–10 years) disease duration periods. Statistical analyses of the fractional anisotropy (FA) data were performed using tract-based spatial statistics (TBSS). Whole-brain skeletal FA measurements showed a significant decrease between healthy controls and the short MS disease duration group, as well as between moderate disease duration and long disease duration groups, but failed to show a significant difference between short and moderate disease duration groups. Voxelwise analysis revealed clusters of diffuse FA reductions in 40 WM tracts when comparing healthy controls and MS short disease duration group, with the point of maximal significant difference located in the left inferior longitudinal fasciculus. Comparing short with long disease duration groups, progressive FA reduction was demonstrated across 30 WM tracts, with the point of maximal significant difference migrating to the body of the corpus callosum. A non-linear pattern of WM microstructure disruption occurs in RRMS. Alterations are seen early in the disease course within 1 year from onset, reach a plateau within the next 5 years, and only later additional WM changes are detected. An important period of a possible therapeutic window therefore exists within the early disease stage. A non-linear pattern of WM microstructure disruption occurs in patients with RRMS. WM disruption is identified within 1 year from disease onset. FA reduction is similar in patients with early and moderate disease duration periods. Different patterns of WM disruption occur in patients with longer disease duration.
Collapse
Affiliation(s)
- Achiron Asaf
- Multiple Sclerosis Center, Sheba Medical Center, Tel-Hashomer, Ramat-Gan, Israel
| | - Stone Evan
- Multiple Sclerosis Center, Sheba Medical Center, Tel-Hashomer, Ramat-Gan, Israel
| | - Achiron Anat
- Multiple Sclerosis Center, Sheba Medical Center, Tel-Hashomer, Ramat-Gan, Israel
| |
Collapse
|
6
|
Paldino MJ, Hedges K, Zhang W. Independent contribution of individual white matter pathways to language function in pediatric epilepsy patients. Neuroimage Clin 2014; 6:327-32. [PMID: 25379446 PMCID: PMC4215459 DOI: 10.1016/j.nicl.2014.09.017] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Revised: 09/22/2014] [Accepted: 09/26/2014] [Indexed: 10/29/2022]
Abstract
BACKGROUND AND PURPOSE Patients with epilepsy and malformations of cortical development (MCDs) are at high risk for language and other cognitive impairment. Specific impairments, however, are not well correlated with the extent and locale of dysplastic cortex; such findings highlight the relevance of aberrant cortico-cortical interactions, or connectivity, to the clinical phenotype. The goal of this study was to determine the independent contribution of well-described white matter pathways to language function in a cohort of pediatric patients with epilepsy. MATERIALS AND METHODS Patients were retrospectively identified from an existing database of pediatric epilepsy patients with the following inclusion criteria: 1. diagnosis of MCDs, 2. DTI performed at 3 T, and 3. language characterized by a pediatric neurologist. Diffusion Toolkit and Trackvis (http://www.trackvis.org) were used for segmentation and analysis of the following tracts: corpus callosum, corticospinal tracts, inferior longitudinal fasciculi (ILFs), inferior fronto-occipital fasciculi (IFOFs), uncinate fasciculi (UFs), and arcuate fasciculi (AFs). Mean diffusivity (MD) and fractional anisotropy (FA) were calculated for each tract. Wilcoxon rank sum test (corrected for multiple comparisons) was used to assess potential differences in tract parameters between language-impaired and language-intact patients. In a separate analysis, a machine learning algorithm (random forest approach) was applied to measure the independent contribution of the measured diffusion parameters for each tract to the clinical phenotype (language impairment). In other words, the importance of each tract parameter was measured after adjusting for the contribution of all other tracts. RESULTS Thirty-three MCD patients were included (age range: 3-18 years). Twenty-one patients had intact language, twelve had language impairment. All tracts were identified bilaterally in all patients except for the AF, which was not identified on the right in 10 subjects and not identified on the left in 11 subjects. MD and/or FA within the left AF, UF, ILF, and IFOF differed between language-intact and language-impaired groups. However, only parameters related to the left uncinate, inferior fronto-occipital, and arcuate fasciculi were independently associated with the clinical phenotype. CONCLUSIONS Scalar metrics derived from the left uncinate, inferior fronto-occipital, and arcuate fasciculi were independently associated with language function. These results support the importance of these pathways in human language function in patients with MCDs.
Collapse
Key Words
- AF, arcuate fasciculus
- Arcuate fasciculus
- BA, Broca's area
- Connectivity
- DTI, diffusion tensor imaging
- DWI, diffusion-weighted imaging
- Epilepsy
- FA, fractional anisotropy
- IFOF, inferior fronto-occipital fasciculus
- ILF, inferior longitudinal fasciculus
- Inferior fronto-occipital fasciculus
- Language
- MCDs, malformations of cortical development
- MD, mean diffusivity
- Malformations of cortical development
- Tractography
- UF, uncinate fasciculus
- Uncinate fasciculus
- WA, Wernicke's area
Collapse
Affiliation(s)
- Michael J Paldino
- Department of Radiology, Children's Hospital Boston and Harvard Medical School, Boston, MA 02115, USA
| | - Kara Hedges
- Department of Radiology, Children's Hospital Boston and Harvard Medical School, Boston, MA 02115, USA
| | - Wei Zhang
- Outcomes and Impact Service, Texas Children's Hospital, Houston, TX 77030, USA
| |
Collapse
|
7
|
Benitez A, Fieremans E, Jensen JH, Falangola MF, Tabesh A, Ferris SH, Helpern JA. White matter tract integrity metrics reflect the vulnerability of late-myelinating tracts in Alzheimer's disease. Neuroimage Clin 2013; 4:64-71. [PMID: 24319654 PMCID: PMC3853114 DOI: 10.1016/j.nicl.2013.11.001] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Revised: 11/01/2013] [Accepted: 11/03/2013] [Indexed: 12/21/2022]
Abstract
Post-mortem and imaging studies have observed that white matter (WM) degenerates in a pattern inverse to myelin development, suggesting preferential regional vulnerabilities influencing cognitive decline in AD. This study applied novel WM tract integrity (WMTI) metrics derived from diffusional kurtosis imaging (DKI) to examine WM tissue properties in AD within this framework. Using data from amnestic mild cognitive impairment (aMCI, n = 12), AD (n = 14), and normal control (NC; n = 15) subjects, mixed models revealed interaction effects: specific WMTI metrics of axonal density and myelin integrity (i.e. axonal water fraction, radial extra-axonal diffusivity) in late-myelinating tracts (i.e. superior and inferior longitudinal fasciculi) changed in the course of disease, but were stable in the initial stages for early-myelinating tracts (i.e. posterior limb of the internal capsule, cerebral peduncles). WMTI metrics in late-myelinating tracts correlated with semantic verbal fluency, a cognitive function known to decline in AD. These findings corroborate the preferential vulnerability of late-myelinating tracts, and illustrate an application of WMTI metrics to characterizing the regional course of WM changes in AD. We investigated the vulnerability of late-myelinating tracts in AD using WMTI metrics. WMTI metrics are derived from the biophysical modeling of the DKI signal. These metrics indicate pathological features like axonal density and myelin integrity. WMTI metrics were largely stable in early-myelinating tracts through the course of AD. Axonal density loss & myelin breakdown were observed in late-myelinating tracts.
Collapse
Key Words
- AD, Alzheimer's disease
- AWF, axonal water fraction
- Alzheimer's disease
- CP, cerebral peduncle
- DKI, diffusional kurtosis imaging
- DTI, diffusion tensor imaging
- Daxon, intrinsic axonal diffusivity
- De,∥, axial extra-axonal diffusivity
- De,⊥, radial extra-axonal diffusivity
- Diffusion MRI
- Diffusional kurtosis imaging
- FA, fractional anisotropy
- ILF, inferior longitudinal fasciculus
- NC, normal control
- PLIC, posterior limb of the internal capsule
- SLF, superior longitudinal fasciculus
- Verbal fluency
- WM, white matter
- WMTI, white matter tract integrity
- White matter
- aMCI, amnestic mild cognitive impairment
Collapse
Affiliation(s)
- Andreana Benitez
- Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC 29425, USA ; Center for Biomedical Imaging, Medical University of South Carolina, Charleston, SC 29425, USA
| | | | | | | | | | | | | |
Collapse
|
8
|
Bakhtiari R, Zürcher NR, Rogier O, Russo B, Hippolyte L, Granziera C, Araabi BN, Nili Ahmadabadi M, Hadjikhani N. Differences in white matter reflect atypical developmental trajectory in autism: A Tract-based Spatial Statistics study. Neuroimage Clin 2012; 1:48-56. [PMID: 24179736 PMCID: PMC3757732 DOI: 10.1016/j.nicl.2012.09.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/09/2012] [Revised: 08/20/2012] [Accepted: 09/03/2012] [Indexed: 12/03/2022]
Abstract
Autism is a neurodevelopmental disorder in which white matter (WM) maturation is affected. We assessed WM integrity in 16 adolescents and 14 adults with high-functioning autism spectrum disorder (ASD) and in matched neurotypical controls (NT) using diffusion weighted imaging and Tract-based Spatial Statistics. Decreased fractional anisotropy (FA) was observed in adolescents with ASD in tracts involved in emotional face processing, language, and executive functioning, including the inferior fronto-occipital fasciculus and the inferior and superior longitudinal fasciculi. Remarkably, no differences in FA were observed between ASD and NT adults. We evaluated the effect of age on WM development across the entire age range. Positive correlations between FA values and age were observed in the right inferior fronto-occipital fasciculus, the left superior longitudinal fasciculus, the corpus callosum, and the cortical spinal tract of ASD participants, but not in NT participants. Our data underscore the dynamic nature of brain development in ASD, showing the presence of an atypical process of WM maturation, that appears to normalize over time and could be at the basis of behavioral improvements often observed in high-functioning autism.
Collapse
Key Words
- ADI-R, Autism Diagnostic Interview-Revised
- ADOS, Autism Diagnostic Observation Schedule
- AQ, Autism Quotient
- ASD, Autism Spectrum Disorders
- ATR, anterior thalamic radiations
- Autism spectrum disorder
- Brain connectivity
- Brain development
- Brain maturation
- CC, corpus callosum
- CT, corticospinal tract
- DTI, Diffusion Tensor Imaging
- DTT, Diffusion Tensor Tractography
- Diffusion Tensor Imaging
- EF, executive functions
- FA, fractional anisotropy
- Fractional anisotropy
- IFOF, inferior froto-occipital fasciculus
- ILF, inferior longitudinal fasciculus
- NT, neurotypical
- PIQ, Performance Intelligence Quotient
- SLF, superior longitudinal fasciculus
- TBSS, Tract-based Spatial Statistics
- TE, echo time
- TFCE, Threshold-free Cluster Enhancement
- TR, repetition time
- UNC, uncinate fasciculus
- VBM, Voxel-Based Morphometry
- VBS, Voxel based Statistics of FA Images (VBM-like)
- WM, white matter
Collapse
Affiliation(s)
- Reyhaneh Bakhtiari
- Control and Intelligent Processing Center of Excellence, School of Electrical and Computer Engineering, College of Engineering, University of Tehran, Tehran, Iran ; Department of Cognitive Sciences, Institute for Research in Fundamental Sciences (IPM), Tehran, Iran ; Brain Mind Institute, Ecole Polytechnique Fédérale, Lausanne, Switzerland
| | | | | | | | | | | | | | | | | |
Collapse
|