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Sökning: WFRF:(Looi JCL)

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1.
  • Lindberg, Olof, et al. (författare)
  • Cortical morphometric subclassification of frontotemporal lobar degeneration
  • 2009
  • Ingår i: American Journal of Neuroradiology. - 0195-6108 .- 1936-959X. ; 30:6, s. 1233-1239
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND AND PURPOSE: Frontotemporal lobar degeneration (FTLD) is a primary neurodegenerative disease comprising 3 clinical subtypes: frontotemporal dementia (FTD), semantic dementia (SD), and progressive nonfluent aphasia (PNFA). The subdivision is primarily based on the characteristic clinical symptoms displayed by each subtype. We hypothesized that these symptoms would be correlated to characteristic patterns of brain atrophy, which could be indentified and used for subclassification of subjects with FTLD. MATERIALS AND METHODS: Volumes of 9 cortical regions were manually parcellated and measured on both hemispheres on 27 controls, 12 patients with FTD, 9 patients with PNFA, and 13 patients with SD. The volumetric data were analyzed by traditional t tests and by a multivariate discriminant analysis (partial least squares discriminant analysis). RESULTS: The ensemble or pattern of atrophy was a good discriminator in pair-wise comparison between the subtypes: FTD compared with SD (sensitivity 100% [12/12], specificity 100% [13/13]); FTD compared with PNFA (sensitivity 92% [11/12], specificity 89% [8/9]); and SD compared with PNFA (sensitivity 86% [11/13], specificity 100% [9/9]). Temporal-versus-frontal atrophy was the most important pattern for discriminating SD from the other 2 subtypes. Right-sided versus left-sided atrophy was the most important pattern for discriminating between subjects with FTD and PNFA. CONCLUSIONS: FTLD subtypes generally display a characteristic pattern of atrophy, which may be considered in diagnosing patients with FTLD.
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2.
  • Lindberg, Olof, et al. (författare)
  • Hippocampal Shape Analysis in Alzheimer's Disease and Frontotemporal Lobar Degeneration Subtypes
  • 2012
  • Ingår i: Journal of Alzheimer's Disease. - 1387-2877 .- 1875-8908. ; 30:2, s. 355-365
  • Tidskriftsartikel (refereegranskat)abstract
    • Hippocampal pathology is central to Alzheimer's disease (AD) and other forms of dementia such as frontotemporal lobar degeneration (FTLD). Autopsy studies have shown that certain hippocampal subfields are more vulnerable than others to AD and FTLD pathology, in particular the subiculum and cornu ammonis 1 (CA1). We conducted shape analysis of hippocampi segmented from structural T1 MRI images on clinically diagnosed dementia patients and controls. The subjects included 19 AD and 35 FTLD patients [13 frontotemporal dementia (FTD), 13 semantic dementia (SD), and 9 progressive nonfluent aphasia (PNFA)] and 21 controls. Compared to controls, SD displayed severe atrophy of the whole left hippocampus. PNFA and FTD also displayed atrophy on the left side, restricted to the hippocampal head in FTD. Finally, AD displayed most atrophy in left hippocampal body with relative sparing of the hippocampal head. Consistent with neuropathological studies, most atrophic deformation was found in CA1 and subiculum areas in FTLD and AD.
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3.
  • Looi Chee Leong, Jeffrey, et al. (författare)
  • Caudate nucleus volumes in frontotemporal lobar degeneration : differential atrophy in subtypes
  • 2008
  • Ingår i: American Journal of Neuroradiology. - 0195-6108 .- 1936-959X. ; 29:8, s. 1537-1543
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND AND PURPOSE: Frontostriatal circuits involving the caudate nucleus have been implicated in frontotemporal lobar degeneration (FTLD). We assessed caudate nucleus volumetrics in FTLD and subtypes: frontotemporal dementia (FTD, n = 12), semantic dementia (SD, n = 13), and progressive nonfluent aphasia (PNFA, n = 9) in comparison with healthy controls (n = 27) and subjects with Alzheimer disease (AD, n = 19). MATERIALS AND METHODS: Diagnoses were based on accepted clinical criteria. Manual volume measurement of the head and body of the caudate, excluding the tail, was conducted on T1-weighted brain MR imaging scans, using a published protocol, by a single analyst blinded to the diagnosis. RESULTS: Paired t tests (P < .05) showed that the right caudate nucleus volume was significantly larger than the left in controls and PNFA. No hemispheric asymmetry was found in AD, ETD, and SD. Across the groups, there was a positive partial correlation between the left caudate nucleus volume and Mini-Mental State Examination (MMSE) scores (r = 0.393, n = 76, P = .001) with higher left caudate volumes associated with higher MMSE scores. Multivariate analysis of covariance was used to assess the statistical significance between the subject groups (AD, ETD, SD, PNFA, and controls) as independent variables and raw right/left caudate volumes at the within-subject level (covariates: age and intracranial volume; P < .05). Control volume was largest, followed by AD (93% of control volume), SD (92%), PNFA (79%), and ETD (75%). CONCLUSIONS: Volume of the head and body of the caudate nucleus differs in subtypes of FTLD, due to differential frontostriatal dysfunction in subtypes being reflected in structural change in the caudate, and is correlated with cognition
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4.
  • Looi, Jefferey Chee Leong, et al. (författare)
  • Shape analysis of the neostriatum in frontotemporal lobar degeneration, Alzheimer's disease, and controls
  • 2010
  • Ingår i: NeuroImage. - 1053-8119 .- 1095-9572. ; 51:3, s. 970-986
  • Tidskriftsartikel (refereegranskat)abstract
    • Background and purpose: Frontostriatal circuit mediated cognitive dysfunction has been implicated in frontotemporal lobar degeneration (FTLD), but not Alzheimer's disease, or healthy aging. We measured the neostriatum (caudate nucleus and putamen) volume in FTLD (n=34), in comparison with controls (n=27) and Alzheimer's disease (AD, n=19) subjects. Methods: Diagnoses were based on international consensus criteria. Manual bilateral segmentation of the caudate nucleus and putamen was conducted blind to diagnosis by a single analyst, on MRI scans using a standardized protocol. Intra-cranial volume was calculated via a stereological point counting technique and was used for scaling the shape analysis. The manual segmentation binaries were analyzed using UNC Shape Analysis tools (University of North Carolina) to perform comparisons among FTLD, AD, and controls for global shape, local p-value significance maps, and mean magnitude of shape displacement. Results: Shape analysis revealed that there was significant shape difference between FTLD, AD, and controls, consistent with the predicted frontostriatal dysfunction and of significant magnitude, as measured by displacement maps. There was a lateralized difference in shape for the left caudate for FTLD compared to AD; non-specific global atrophy in AD compared to controls; while FTLD showed a more specific pattern in regions relaying fronto- and corticostriatal circuits. Conclusions: Shape analysis shows regional specificity of atrophy, manifest as shape deflation, with implications for frontostriatal and corticostriatal motoric circuits, in FTLD, AD, and controls.
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5.
  • Looi, Jeffrey Chee Leong, et al. (författare)
  • Shape analysis of the neostriatum in subtypes of frontotemporal lobar degeneration : neuroanatomically significant regional morphologic change
  • 2011
  • Ingår i: Psychiatry Research. - 0925-4927 .- 1872-7506. ; 191:2, s. 98-111
  • Tidskriftsartikel (refereegranskat)abstract
    • Frontostriatal circuit mediated cognitive dysfunction has been implicated in frontotemporal lobar degeneration (FTLD) and may differ across subtypes of FTLD. We manually segmented the neostriatum (caudate nucleus and putamen) in FTLD subtypes: behavioral variant frontotemporal dementia, FTD, n=12; semantic dementia, SD, n=13; and progressive non-fluent aphasia, PNFA, n=9); in comparison with controls (n=27). Diagnoses were based on international consensus criteria. Manual bilateral segmentation of the caudate nucleus and putamen was conducted blind to diagnosis by a single analyst, on MRI scans using a standardized protocol. Intracranial volume was calculated via a stereological point counting technique and was used for normalizing the shape analysis. Segmented binaries were analyzed using the Spherical Harmonic (SPHARM) Shape Analysis tools (University of North Carolina) to perform comparisons between FTLD subtypes and controls for global shape difference, local significance maps and mean magnitude maps of shape displacement. Shape analysis revealed that there was significant shape difference between FTLD subtypes and controls, consistent with the predicted frontostriatal dysfunction and of significant magnitude, as measured by displacement maps. These differences were not significant for SD compared to controls; lesser for PNFA compared to controls; whilst FTD showed a more specific pattern in regions relaying fronto- and corticostriatal circuits. Shape analysis shows regional specificity of atrophy, manifest as shape deflation, with a differential between FTLD subtypes, compared to controls.
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6.
  • Looi, Jeffrey C. L., et al. (författare)
  • The Australian, US, Scandinavian Imaging Exchange (AUSSIE): an innovative, virtually-integrated health research network embedded in health care
  • 2014
  • Ingår i: Australasian Psychiatry. - : SAGE Publications. - 1039-8562. ; 22:3, s. 260-265
  • Tidskriftsartikel (refereegranskat)abstract
    • Objective: To describe the development, design and function of an innovative international clinical research network for neuroimaging research, based in Australia, within a joint state health service/medical school. This Australian, US, Scandinavian Imaging Exchange (AUSSIE) network focuses upon identifying neuroimaging biomarkers for neuropsychiatric and neurodegenerative disease. Methods: We describe a case study of the iterative development of the network, identifying characteristic features and methods which may serve as potential models for virtual clinical research networks. This network was established to analyse clinically-derived neuroimaging data relevant to neuropsychiatric and neurodegenerative disease, specifically in relation to subcortical brain structures. Results: The AUSSIE network has harnessed synergies from the individual expertise of the component groups, primarily clinical neuroscience researchers, to analyse a variety of clinical data. Conclusion: AUSSIE is an active virtual clinical research network, analogous to a connectome, which is embedded in health care and has produced significant research, advancing our understanding of neuropsychiatric and neurodegenerative disease through the lens of neuroimaging.
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9.
  • Looi, JC, et al. (författare)
  • Putaminal volume in frontotemporal lobar degeneration and Alzheimer disease: differential volumes in dementia subtypes and controls
  • 2009
  • Ingår i: American Journal of Neuroradiology. - 0195-6108 .- 1936-959X. ; 30:8, s. 1552-1560
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND AND PURPOSE: Frontostriatal (including the putamen) circuit-mediated cognitive dysfunction has been implicated in frontotemporal lobar degeneration (FTLD), but not in Alzheimer disease (AD) or healthy aging. We sought to assess putaminal volume as a measure of the structural basis of relative frontostriatal dysfunction in these groups. MATERIALS AND METHODS: We measured putaminal volume in FTLD subtypes: frontotemporal dementia (FTD, n = 12), semantic dementia (SD, n = 13), and progressive nonfluent aphasia (PNFA, n = 9) in comparison with healthy controls (n = 25) and patients with AD (n = 18). Diagnoses were based on accepted clinical criteria. We conducted manual volume measurement of the putamen blinded to the diagnosis on T1 brain MR imaging by using a standardized protocol. RESULTS: Paired t tests (P < .05) showed that the left putaminal volume was significantly larger than the right in all groups combined. Multivariate analysis of covariance with a Bonferroni correction was used to assess statistical significance among the subject groups (AD, FTD, SD, PNFA, and controls) as independent variables and right/left putaminal volumes as dependent variables (covariates, age and intracranial volume; P < .05). The right putamen in FTD was significantly smaller than in AD and controls; whereas in SD, it was smaller compared with controls with a trend toward being smaller than in AD. There was also a trend toward the putamen in the PNFA being smaller than that in controls and in patients with AD. Across the groups, there was a positive partial correlation between putaminal volume and Mini-Mental State Examination (MMSE). CONCLUSIONS: Right putaminal volume was significantly smaller in FTD, the FTLD subtype with the greatest expected frontostriatal dysfunction; whereas in SD and PNFA, it showed a trend towards being smaller, consistent with expectation, compared to controls and AD; and in SD, compared with AD and controls. Putaminal volume weakly correlated with MMSE.
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10.
  • Macfarlane, M. D., et al. (författare)
  • Shape abnormalities of the caudate nucleus correlate with poorer gait and balance: Results from a subset of the ladis study
  • 2015
  • Ingår i: The American journal of geriatric psychiatry. - 1064-7481. ; 23:1, s. 59-U90
  • Tidskriftsartikel (refereegranskat)abstract
    • Objective Functional deficits seen in several neurodegenerative disorders have been linked with dysfunction in frontostriatal circuits and with associated shape alterations in striatal structures. The severity of visible white matter hyperintensities (WMHs) on magnetic resonance imaging has been found to correlate with poorer performance on measures of gait and balance. This study aimed to determine whether striatal volume and shape changes were correlated with gait dysfunction. Methods Magnetic resonance imaging scans and clinical gait/balance data (scores from the Short Physical Performance Battery [SPPB]) were sourced from 66 subjects in the previously published LADIS trial, performed in nondisabled individuals older than age 65 years with WMHs at study entry. Data were obtained at study entry and at 3-year follow-up. Caudate nuclei and putamina were manually traced using a previously published method and volumes calculated. The relationships between volume and physical performance on the SPPB were investigated with shape analysis using the spherical harmonic shape description toolkit. Results There was no correlation between the severity of WMHs and striatal volumes. Caudate nuclei volume correlated with performance on the SPPB at baseline but not at follow-up, with subsequent shape analysis showing left caudate changes occurred in areas corresponding to inputs of the dorsolateral prefrontal, premotor, and motor cortex. There was no correlation between putamen volumes and performance on the SPPB. Conclusion Disruption in frontostriatal circuits may play a role in mediating poorer physical performance in individuals with WMHs. Striatal volume and shape changes may be suitable biomarkers for functional changes in this population. © 2015 American Association for Geriatric Psychiatry.
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