The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform
Joanna M Wardlaw - One of the best experts on this subject based on the ideXlab platform.
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Perivascular spaces in the centrum semiovale at the beginning of the 8th decade of life: effect on cognition and associations with mineral deposition
Brain Imaging and Behavior, 2019Co-Authors: Maria Del C. Valdés Hernández, Andreas Glatz, Mark E Bastin, John M Starr, Ian J Deary, Lucia Ballerini, Susana Muñoz Maniega, Joanna M WardlawAbstract:Brain Iron Deposits (IDs) are indicative of microvessel dysfunction which may predispose to small vessel disease (SVD) brain damage and worsen cognition later in life. Visible perivascular spaces in the centrum semiovale (CSO-PVS) are SVD features linked with microvessel dysfunction. We examined possible associations of CSO-PVS volume and count with brain IDs and cognitive abilities in 700 community-dwelling individuals from the Lothian Birth Cohort 1936 who underwent detailed cognitive testing and multimodal brain MRI at mean age 72.7 years. Brain IDs were assessed automatically followed by manual editing. PVS were automatically assessed in the centrum semiovale and deep corona radiata supraventricular. General factors of overall cognitive function (g), processing speed (g-speed) and memory (g-memory) were used in the analyses. Median (IQR) volumes of IDs and CSO-PVS expressed as a percentage of intracranial volume were 0.0021 (0.011) and 0.22 (0.13)% respectively. Median count of CSO-PVS was 410 (IQR = 201). Total volumes of CSO-PVS and ID, adjusted for head size, were correlated (Spearman ρ = 0.13, p
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brain Iron Deposits and lifespan cognitive ability
Age, 2015Co-Authors: Maria Del C Valdes Hernandez, Stuart J Ritchie, Andreas Glatz, Michael Allerhand, Susana Munoz Maniega, Natalie A Royle, Mark E Bastin, John M Starr, Ian J Deary, Joanna M WardlawAbstract:Several studies have reported associations between brain Iron Deposits and cognitive status, and cardiovascular and neurodegenerative diseases in older individuals, but the mechanisms underlying these asso- ciations remain unclear. We explored the associations between regional brain Iron Deposits and different fac- tors of cognitive ability (fluid intelligence, speed and memory) in a large sample (n=662) of individuals with a meanage of73years.Brain IronDepositsinthe corpus striatum were extracted automatically. Iron Deposits in other parts of the brain (i.e., white matter, thalamus, brainstem and cortex), brain tissue volume and white matter hyperintensities (WMH) were assessed separate- ly and semi-automatically. Overall, 72.8 % of the sample had Iron Deposits. The total volume of Iron Deposits had a small but significant negative association with all three cognitive ability factors in later life (mean r=−0.165), but no relation to intelligence in childhood (r=0.043, p=0.282). Regression models showed that these Iron deposit associations were still present after control for a variety of vascular health factors, and were separable from the association of WMH with cognitive ability.IronDepositswerealsoassociatedwith cognition across the lifespan, indicating that they are relevant for cognitive ability only at older ages. Iron Deposits might be an indicator of small vessel disease that affects the neuronal networks underlying higher cognitive functioning.
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differentiation of calcified regions and Iron Deposits in the ageing brain on conventional structural mr images
Journal of Magnetic Resonance Imaging, 2014Co-Authors: Maria Del C Valdes Hernandez, Andreas Glatz, Susana Munoz Maniega, Natalie A Royle, Mark E Bastin, Ian J Deary, Alexander J. Kiker, David Alexander Dickie, Benjamin S. Aribisala, Joanna M WardlawAbstract:Purpose In the human brain, minerals such as Iron and calcium accumulate increasingly with age. They typically appear hypointense on T2*-weighted MRI sequences. This study aims to explore the differentiation and association between calcified regions and noncalcified Iron Deposits on clinical brain MRI in elderly, otherwise healthy subjects. Materials and Methods Mineral Deposits were segmented on co-registered T1- and T2*-weighted sequences from 100 1.5 Tesla MRI datasets of community-dwelling individuals in their 70s. To differentiate calcified regions from noncalcified Iron Deposits we developed a method based on their appearance on T1-weighted images, which was validated with a purpose-designed phantom. Joint T1- and T2*-weighted intensity histograms were constructed to measure the similarity between the calcified and noncalcified Iron Deposits using a Euclidean distance based metric. Results We found distinct distributions for calcified regions and noncalcified Iron Deposits in the cumulative joint T1- and T2*-weighted intensity histograms across all subjects (correlations ranging from 0.02 to 0.86; mean = 0.26 ± 0.16; t = 16.93; P < 0.001) consistent with differences in Iron and calcium signal in the phantom. The mean volumes of affected tissue per subject for calcified and noncalcified Deposits were 236.74 ± 309.70 mm3 and 283.76 ± 581.51 mm3; respectively. There was a positive association between the mineral depositions (β = 0.32, P < 0.005), consistent with existing literature reports. Conclusion Calcified mineral Deposits and noncalcified Iron Deposits can be distinguished from each other by signal intensity changes on conventional 1.5T T1-weighted MRI and are significantly associated in brains of elderly, otherwise healthy subjects. J. Magn. Reson. Imaging 2014;40:324–333 © 2013 Wiley Periodicals, Inc.
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Differentiation of Calcified Regions and Iron Deposits in the Ageing Brain on Conventional
2013Co-Authors: Andreas Glatz, Natalie A Royle, Mark E Bastin, Ian J Deary, Alexander J. Kiker, David Alexander Dickie, Benjamin S. Aribisala, Joanna M WardlawAbstract:Purpose: In the human brain, minerals such as Iron and calcium accumulate increasingly with age. They typically appear hypointense on T2*-weighted MRI sequences. This study aims to explore the differentiation and association between calcified regions and noncalcified Iron Deposits on clinical brain MRI in elderly, otherwise healthy subjects. Materials and Methods: Mineral Deposits were segmented on co-registered T1- and T2*-weighted sequences from 100 1.5 Tesla MRI datasets of community-dwelling individuals in their 70s. To differentiate calcified regions from noncalcified Iron Deposits we developed a method based on their appearance on T1-weighted images, which was validated with a purpose-designed phantom. Joint T1- and T2*-weighted intensity histograms were constructed to measure the similarity between the calcified and noncalcified Iron Deposits using a Euclidean distance based metric. Results: We found distinct distributions for calcified regions and noncalcified Iron Deposits in the cumulative joint T1- and T2*-weighted intensity histograms across all subjects (correlations ranging from 0.02 to 0.86; mean ¼ 0.26 6 0.16; t ¼ 16.93; P < 0.001) consistent with differences in Iron and calcium signal in the phantom. The mean volumes of affected tissue per subject for calcified and noncalcified Deposits were 236.74 6 309.70 mm 3 and 283.76 6 581.51 mm 3 ; respectively. There was a positive association between the mineral depositions (b ¼ 0.32, P < 0.005), consistent with existing literature reports. Conclusion: Calcified mineral Deposits and noncalcified Iron Deposits can be distinguished from each other by signal intensity changes on conventional 1.5T T1-weighted MRI and are significantly associated in brains of elderly, otherwise healthy subjects.
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brain Iron Deposits are associated with general cognitive ability and cognitive aging
Neurobiology of Aging, 2012Co-Authors: Lars Penke, Susana Munoz Maniega, Mark E Bastin, John M Starr, Ian J Deary, Maria Valdes C Hernandez, Catherine Murray, Joanna M WardlawAbstract:Abstract A novel analysis of magnetic resonance imaging (MRI) scans based on multispectral image fusion was used to quantify Iron Deposits in basal ganglia and microbleeds in 143 nondemented subjects of the generally healthy Lothian Birth Cohort, who were tested for general cognitive ability (intelligence) at mean ages of 11, 70, and 72 years. Possessing more Iron Deposits at age 72 was significantly associated with lower general cognitive ability at age 11, 70, and 72, explaining 4% to 9% of the variance. The relationships with old age general cognitive ability remained significant after controlling for childhood cognition, suggesting that Iron Deposits are related to lifetime cognitive decline. Most Iron Deposits were in the basal ganglia, with few microbleeds. While Iron Deposits in the general population have so far been dismissed in the literature, our results show substantial associations with cognitive functioning. The pattern of results suggests that Iron Deposits are not only a biomarker of general cognitive ability in old age and age-related cognitive decline, but that they are also related to the lifelong-stable trait of intelligence.
Maria Del C Valdes Hernandez - One of the best experts on this subject based on the ideXlab platform.
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brain Iron Deposits and lifespan cognitive ability
Age, 2015Co-Authors: Maria Del C Valdes Hernandez, Stuart J Ritchie, Andreas Glatz, Michael Allerhand, Susana Munoz Maniega, Natalie A Royle, Mark E Bastin, John M Starr, Ian J Deary, Joanna M WardlawAbstract:Several studies have reported associations between brain Iron Deposits and cognitive status, and cardiovascular and neurodegenerative diseases in older individuals, but the mechanisms underlying these asso- ciations remain unclear. We explored the associations between regional brain Iron Deposits and different fac- tors of cognitive ability (fluid intelligence, speed and memory) in a large sample (n=662) of individuals with a meanage of73years.Brain IronDepositsinthe corpus striatum were extracted automatically. Iron Deposits in other parts of the brain (i.e., white matter, thalamus, brainstem and cortex), brain tissue volume and white matter hyperintensities (WMH) were assessed separate- ly and semi-automatically. Overall, 72.8 % of the sample had Iron Deposits. The total volume of Iron Deposits had a small but significant negative association with all three cognitive ability factors in later life (mean r=−0.165), but no relation to intelligence in childhood (r=0.043, p=0.282). Regression models showed that these Iron deposit associations were still present after control for a variety of vascular health factors, and were separable from the association of WMH with cognitive ability.IronDepositswerealsoassociatedwith cognition across the lifespan, indicating that they are relevant for cognitive ability only at older ages. Iron Deposits might be an indicator of small vessel disease that affects the neuronal networks underlying higher cognitive functioning.
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differentiation of calcified regions and Iron Deposits in the ageing brain on conventional structural mr images
Journal of Magnetic Resonance Imaging, 2014Co-Authors: Maria Del C Valdes Hernandez, Andreas Glatz, Susana Munoz Maniega, Natalie A Royle, Mark E Bastin, Ian J Deary, Alexander J. Kiker, David Alexander Dickie, Benjamin S. Aribisala, Joanna M WardlawAbstract:Purpose In the human brain, minerals such as Iron and calcium accumulate increasingly with age. They typically appear hypointense on T2*-weighted MRI sequences. This study aims to explore the differentiation and association between calcified regions and noncalcified Iron Deposits on clinical brain MRI in elderly, otherwise healthy subjects. Materials and Methods Mineral Deposits were segmented on co-registered T1- and T2*-weighted sequences from 100 1.5 Tesla MRI datasets of community-dwelling individuals in their 70s. To differentiate calcified regions from noncalcified Iron Deposits we developed a method based on their appearance on T1-weighted images, which was validated with a purpose-designed phantom. Joint T1- and T2*-weighted intensity histograms were constructed to measure the similarity between the calcified and noncalcified Iron Deposits using a Euclidean distance based metric. Results We found distinct distributions for calcified regions and noncalcified Iron Deposits in the cumulative joint T1- and T2*-weighted intensity histograms across all subjects (correlations ranging from 0.02 to 0.86; mean = 0.26 ± 0.16; t = 16.93; P < 0.001) consistent with differences in Iron and calcium signal in the phantom. The mean volumes of affected tissue per subject for calcified and noncalcified Deposits were 236.74 ± 309.70 mm3 and 283.76 ± 581.51 mm3; respectively. There was a positive association between the mineral depositions (β = 0.32, P < 0.005), consistent with existing literature reports. Conclusion Calcified mineral Deposits and noncalcified Iron Deposits can be distinguished from each other by signal intensity changes on conventional 1.5T T1-weighted MRI and are significantly associated in brains of elderly, otherwise healthy subjects. J. Magn. Reson. Imaging 2014;40:324–333 © 2013 Wiley Periodicals, Inc.
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MIUA - Automatic segmentation of basal ganglia Iron Deposits from structural MRI.
2011Co-Authors: Andreas Glatz, Maria Del C Valdes Hernandez, Susana Munoz Maniega, Natalie A Royle, Mark E Bastin, Ian J Deary, Alexander J. Kiker, Joanna M WardlawAbstract:Brain Iron Deposits have recently been suggested as biomarkers for small brain vessel diseases. Here, we present a novel, automated method for segmenting brain Iron Deposits in the basal ganglia from structural MRI data. It is based on minimum-variance clustering of intensities from T1and T2∗-weighted volumes, and a supervised cluster selection algorithm. This method was evaluated with MR data from 24 subjects and compared with Iron deposit masks segmented manually by an experienced rater. A median Jaccard similarity index of 0.64 between manual and automatically generated segmentation masks is promising and encourages further investigations to improve the computing speed and accuracy of the method.
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reliability of two techniques for assessing cerebral Iron Deposits with structural magnetic resonance imaging
Journal of Magnetic Resonance Imaging, 2011Co-Authors: Maria Del C Valdes Hernandez, Mark E Bastin, Ian J Deary, Catherine Murray, Tina H Jeong, Francesca M Chappell, Joanna M WardlawAbstract:Purpose To test the reliability of two computational methods for segmenting cerebral Iron Deposits (IDs) in the aging brain, given that its measurement in magnetic resonance imaging (MRI) is challenging due to the similar effect produced by other minerals, especially calcium, on T2*-weighted sequences. Materials and Methods T1-, T2*-weighted, and fluid-attenuated inversion recovery (FLAIR) MR brain images obtained at 1.5T from 70 subjects in their early 70s who displayed a wide range of brain IDs were analyzed. The first segmentation method used a multispectral approach based on the fusion of two or more structural sequences registered and mapped in the red/green color space followed by Minimum Variance Quantization. The second method employed a combined thresholding, size and shape analysis using T2*-weighted images augmented with visual information from T1-weighted data. Results Both segmentation techniques had high intra- and interobserver agreement (95% confidence interval [CI] = ± 57 voxels in a range from 0 to 1800), which decreased in subjects with significant microbleeds and/or IDs. However, the thresholding method was more observer dependent in identifying microbleeds and IDs boundaries than the multispectral approach. Conclusion Both techniques proved to be in agreement and have good intra- and interobserver reliability. However, they have limitations, specifically with regard to automation and observer independence, so further work is required to develop fully user-independent methods of identifying cerebral IDs. J. Magn. Reson. Imaging 2011;33:54–61. © 2010 Wiley-Liss, Inc.
Ian J Deary - One of the best experts on this subject based on the ideXlab platform.
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Perivascular spaces in the centrum semiovale at the beginning of the 8th decade of life: effect on cognition and associations with mineral deposition
Brain Imaging and Behavior, 2019Co-Authors: Maria Del C. Valdés Hernández, Andreas Glatz, Mark E Bastin, John M Starr, Ian J Deary, Lucia Ballerini, Susana Muñoz Maniega, Joanna M WardlawAbstract:Brain Iron Deposits (IDs) are indicative of microvessel dysfunction which may predispose to small vessel disease (SVD) brain damage and worsen cognition later in life. Visible perivascular spaces in the centrum semiovale (CSO-PVS) are SVD features linked with microvessel dysfunction. We examined possible associations of CSO-PVS volume and count with brain IDs and cognitive abilities in 700 community-dwelling individuals from the Lothian Birth Cohort 1936 who underwent detailed cognitive testing and multimodal brain MRI at mean age 72.7 years. Brain IDs were assessed automatically followed by manual editing. PVS were automatically assessed in the centrum semiovale and deep corona radiata supraventricular. General factors of overall cognitive function (g), processing speed (g-speed) and memory (g-memory) were used in the analyses. Median (IQR) volumes of IDs and CSO-PVS expressed as a percentage of intracranial volume were 0.0021 (0.011) and 0.22 (0.13)% respectively. Median count of CSO-PVS was 410 (IQR = 201). Total volumes of CSO-PVS and ID, adjusted for head size, were correlated (Spearman ρ = 0.13, p
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brain Iron Deposits and lifespan cognitive ability
Age, 2015Co-Authors: Maria Del C Valdes Hernandez, Stuart J Ritchie, Andreas Glatz, Michael Allerhand, Susana Munoz Maniega, Natalie A Royle, Mark E Bastin, John M Starr, Ian J Deary, Joanna M WardlawAbstract:Several studies have reported associations between brain Iron Deposits and cognitive status, and cardiovascular and neurodegenerative diseases in older individuals, but the mechanisms underlying these asso- ciations remain unclear. We explored the associations between regional brain Iron Deposits and different fac- tors of cognitive ability (fluid intelligence, speed and memory) in a large sample (n=662) of individuals with a meanage of73years.Brain IronDepositsinthe corpus striatum were extracted automatically. Iron Deposits in other parts of the brain (i.e., white matter, thalamus, brainstem and cortex), brain tissue volume and white matter hyperintensities (WMH) were assessed separate- ly and semi-automatically. Overall, 72.8 % of the sample had Iron Deposits. The total volume of Iron Deposits had a small but significant negative association with all three cognitive ability factors in later life (mean r=−0.165), but no relation to intelligence in childhood (r=0.043, p=0.282). Regression models showed that these Iron deposit associations were still present after control for a variety of vascular health factors, and were separable from the association of WMH with cognitive ability.IronDepositswerealsoassociatedwith cognition across the lifespan, indicating that they are relevant for cognitive ability only at older ages. Iron Deposits might be an indicator of small vessel disease that affects the neuronal networks underlying higher cognitive functioning.
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differentiation of calcified regions and Iron Deposits in the ageing brain on conventional structural mr images
Journal of Magnetic Resonance Imaging, 2014Co-Authors: Maria Del C Valdes Hernandez, Andreas Glatz, Susana Munoz Maniega, Natalie A Royle, Mark E Bastin, Ian J Deary, Alexander J. Kiker, David Alexander Dickie, Benjamin S. Aribisala, Joanna M WardlawAbstract:Purpose In the human brain, minerals such as Iron and calcium accumulate increasingly with age. They typically appear hypointense on T2*-weighted MRI sequences. This study aims to explore the differentiation and association between calcified regions and noncalcified Iron Deposits on clinical brain MRI in elderly, otherwise healthy subjects. Materials and Methods Mineral Deposits were segmented on co-registered T1- and T2*-weighted sequences from 100 1.5 Tesla MRI datasets of community-dwelling individuals in their 70s. To differentiate calcified regions from noncalcified Iron Deposits we developed a method based on their appearance on T1-weighted images, which was validated with a purpose-designed phantom. Joint T1- and T2*-weighted intensity histograms were constructed to measure the similarity between the calcified and noncalcified Iron Deposits using a Euclidean distance based metric. Results We found distinct distributions for calcified regions and noncalcified Iron Deposits in the cumulative joint T1- and T2*-weighted intensity histograms across all subjects (correlations ranging from 0.02 to 0.86; mean = 0.26 ± 0.16; t = 16.93; P < 0.001) consistent with differences in Iron and calcium signal in the phantom. The mean volumes of affected tissue per subject for calcified and noncalcified Deposits were 236.74 ± 309.70 mm3 and 283.76 ± 581.51 mm3; respectively. There was a positive association between the mineral depositions (β = 0.32, P < 0.005), consistent with existing literature reports. Conclusion Calcified mineral Deposits and noncalcified Iron Deposits can be distinguished from each other by signal intensity changes on conventional 1.5T T1-weighted MRI and are significantly associated in brains of elderly, otherwise healthy subjects. J. Magn. Reson. Imaging 2014;40:324–333 © 2013 Wiley Periodicals, Inc.
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Differentiation of Calcified Regions and Iron Deposits in the Ageing Brain on Conventional
2013Co-Authors: Andreas Glatz, Natalie A Royle, Mark E Bastin, Ian J Deary, Alexander J. Kiker, David Alexander Dickie, Benjamin S. Aribisala, Joanna M WardlawAbstract:Purpose: In the human brain, minerals such as Iron and calcium accumulate increasingly with age. They typically appear hypointense on T2*-weighted MRI sequences. This study aims to explore the differentiation and association between calcified regions and noncalcified Iron Deposits on clinical brain MRI in elderly, otherwise healthy subjects. Materials and Methods: Mineral Deposits were segmented on co-registered T1- and T2*-weighted sequences from 100 1.5 Tesla MRI datasets of community-dwelling individuals in their 70s. To differentiate calcified regions from noncalcified Iron Deposits we developed a method based on their appearance on T1-weighted images, which was validated with a purpose-designed phantom. Joint T1- and T2*-weighted intensity histograms were constructed to measure the similarity between the calcified and noncalcified Iron Deposits using a Euclidean distance based metric. Results: We found distinct distributions for calcified regions and noncalcified Iron Deposits in the cumulative joint T1- and T2*-weighted intensity histograms across all subjects (correlations ranging from 0.02 to 0.86; mean ¼ 0.26 6 0.16; t ¼ 16.93; P < 0.001) consistent with differences in Iron and calcium signal in the phantom. The mean volumes of affected tissue per subject for calcified and noncalcified Deposits were 236.74 6 309.70 mm 3 and 283.76 6 581.51 mm 3 ; respectively. There was a positive association between the mineral depositions (b ¼ 0.32, P < 0.005), consistent with existing literature reports. Conclusion: Calcified mineral Deposits and noncalcified Iron Deposits can be distinguished from each other by signal intensity changes on conventional 1.5T T1-weighted MRI and are significantly associated in brains of elderly, otherwise healthy subjects.
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brain Iron Deposits are associated with general cognitive ability and cognitive aging
Neurobiology of Aging, 2012Co-Authors: Lars Penke, Susana Munoz Maniega, Mark E Bastin, John M Starr, Ian J Deary, Maria Valdes C Hernandez, Catherine Murray, Joanna M WardlawAbstract:Abstract A novel analysis of magnetic resonance imaging (MRI) scans based on multispectral image fusion was used to quantify Iron Deposits in basal ganglia and microbleeds in 143 nondemented subjects of the generally healthy Lothian Birth Cohort, who were tested for general cognitive ability (intelligence) at mean ages of 11, 70, and 72 years. Possessing more Iron Deposits at age 72 was significantly associated with lower general cognitive ability at age 11, 70, and 72, explaining 4% to 9% of the variance. The relationships with old age general cognitive ability remained significant after controlling for childhood cognition, suggesting that Iron Deposits are related to lifetime cognitive decline. Most Iron Deposits were in the basal ganglia, with few microbleeds. While Iron Deposits in the general population have so far been dismissed in the literature, our results show substantial associations with cognitive functioning. The pattern of results suggests that Iron Deposits are not only a biomarker of general cognitive ability in old age and age-related cognitive decline, but that they are also related to the lifelong-stable trait of intelligence.
Mark E Bastin - One of the best experts on this subject based on the ideXlab platform.
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Perivascular spaces in the centrum semiovale at the beginning of the 8th decade of life: effect on cognition and associations with mineral deposition
Brain Imaging and Behavior, 2019Co-Authors: Maria Del C. Valdés Hernández, Andreas Glatz, Mark E Bastin, John M Starr, Ian J Deary, Lucia Ballerini, Susana Muñoz Maniega, Joanna M WardlawAbstract:Brain Iron Deposits (IDs) are indicative of microvessel dysfunction which may predispose to small vessel disease (SVD) brain damage and worsen cognition later in life. Visible perivascular spaces in the centrum semiovale (CSO-PVS) are SVD features linked with microvessel dysfunction. We examined possible associations of CSO-PVS volume and count with brain IDs and cognitive abilities in 700 community-dwelling individuals from the Lothian Birth Cohort 1936 who underwent detailed cognitive testing and multimodal brain MRI at mean age 72.7 years. Brain IDs were assessed automatically followed by manual editing. PVS were automatically assessed in the centrum semiovale and deep corona radiata supraventricular. General factors of overall cognitive function (g), processing speed (g-speed) and memory (g-memory) were used in the analyses. Median (IQR) volumes of IDs and CSO-PVS expressed as a percentage of intracranial volume were 0.0021 (0.011) and 0.22 (0.13)% respectively. Median count of CSO-PVS was 410 (IQR = 201). Total volumes of CSO-PVS and ID, adjusted for head size, were correlated (Spearman ρ = 0.13, p
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brain Iron Deposits and lifespan cognitive ability
Age, 2015Co-Authors: Maria Del C Valdes Hernandez, Stuart J Ritchie, Andreas Glatz, Michael Allerhand, Susana Munoz Maniega, Natalie A Royle, Mark E Bastin, John M Starr, Ian J Deary, Joanna M WardlawAbstract:Several studies have reported associations between brain Iron Deposits and cognitive status, and cardiovascular and neurodegenerative diseases in older individuals, but the mechanisms underlying these asso- ciations remain unclear. We explored the associations between regional brain Iron Deposits and different fac- tors of cognitive ability (fluid intelligence, speed and memory) in a large sample (n=662) of individuals with a meanage of73years.Brain IronDepositsinthe corpus striatum were extracted automatically. Iron Deposits in other parts of the brain (i.e., white matter, thalamus, brainstem and cortex), brain tissue volume and white matter hyperintensities (WMH) were assessed separate- ly and semi-automatically. Overall, 72.8 % of the sample had Iron Deposits. The total volume of Iron Deposits had a small but significant negative association with all three cognitive ability factors in later life (mean r=−0.165), but no relation to intelligence in childhood (r=0.043, p=0.282). Regression models showed that these Iron deposit associations were still present after control for a variety of vascular health factors, and were separable from the association of WMH with cognitive ability.IronDepositswerealsoassociatedwith cognition across the lifespan, indicating that they are relevant for cognitive ability only at older ages. Iron Deposits might be an indicator of small vessel disease that affects the neuronal networks underlying higher cognitive functioning.
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differentiation of calcified regions and Iron Deposits in the ageing brain on conventional structural mr images
Journal of Magnetic Resonance Imaging, 2014Co-Authors: Maria Del C Valdes Hernandez, Andreas Glatz, Susana Munoz Maniega, Natalie A Royle, Mark E Bastin, Ian J Deary, Alexander J. Kiker, David Alexander Dickie, Benjamin S. Aribisala, Joanna M WardlawAbstract:Purpose In the human brain, minerals such as Iron and calcium accumulate increasingly with age. They typically appear hypointense on T2*-weighted MRI sequences. This study aims to explore the differentiation and association between calcified regions and noncalcified Iron Deposits on clinical brain MRI in elderly, otherwise healthy subjects. Materials and Methods Mineral Deposits were segmented on co-registered T1- and T2*-weighted sequences from 100 1.5 Tesla MRI datasets of community-dwelling individuals in their 70s. To differentiate calcified regions from noncalcified Iron Deposits we developed a method based on their appearance on T1-weighted images, which was validated with a purpose-designed phantom. Joint T1- and T2*-weighted intensity histograms were constructed to measure the similarity between the calcified and noncalcified Iron Deposits using a Euclidean distance based metric. Results We found distinct distributions for calcified regions and noncalcified Iron Deposits in the cumulative joint T1- and T2*-weighted intensity histograms across all subjects (correlations ranging from 0.02 to 0.86; mean = 0.26 ± 0.16; t = 16.93; P < 0.001) consistent with differences in Iron and calcium signal in the phantom. The mean volumes of affected tissue per subject for calcified and noncalcified Deposits were 236.74 ± 309.70 mm3 and 283.76 ± 581.51 mm3; respectively. There was a positive association between the mineral depositions (β = 0.32, P < 0.005), consistent with existing literature reports. Conclusion Calcified mineral Deposits and noncalcified Iron Deposits can be distinguished from each other by signal intensity changes on conventional 1.5T T1-weighted MRI and are significantly associated in brains of elderly, otherwise healthy subjects. J. Magn. Reson. Imaging 2014;40:324–333 © 2013 Wiley Periodicals, Inc.
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Differentiation of Calcified Regions and Iron Deposits in the Ageing Brain on Conventional
2013Co-Authors: Andreas Glatz, Natalie A Royle, Mark E Bastin, Ian J Deary, Alexander J. Kiker, David Alexander Dickie, Benjamin S. Aribisala, Joanna M WardlawAbstract:Purpose: In the human brain, minerals such as Iron and calcium accumulate increasingly with age. They typically appear hypointense on T2*-weighted MRI sequences. This study aims to explore the differentiation and association between calcified regions and noncalcified Iron Deposits on clinical brain MRI in elderly, otherwise healthy subjects. Materials and Methods: Mineral Deposits were segmented on co-registered T1- and T2*-weighted sequences from 100 1.5 Tesla MRI datasets of community-dwelling individuals in their 70s. To differentiate calcified regions from noncalcified Iron Deposits we developed a method based on their appearance on T1-weighted images, which was validated with a purpose-designed phantom. Joint T1- and T2*-weighted intensity histograms were constructed to measure the similarity between the calcified and noncalcified Iron Deposits using a Euclidean distance based metric. Results: We found distinct distributions for calcified regions and noncalcified Iron Deposits in the cumulative joint T1- and T2*-weighted intensity histograms across all subjects (correlations ranging from 0.02 to 0.86; mean ¼ 0.26 6 0.16; t ¼ 16.93; P < 0.001) consistent with differences in Iron and calcium signal in the phantom. The mean volumes of affected tissue per subject for calcified and noncalcified Deposits were 236.74 6 309.70 mm 3 and 283.76 6 581.51 mm 3 ; respectively. There was a positive association between the mineral depositions (b ¼ 0.32, P < 0.005), consistent with existing literature reports. Conclusion: Calcified mineral Deposits and noncalcified Iron Deposits can be distinguished from each other by signal intensity changes on conventional 1.5T T1-weighted MRI and are significantly associated in brains of elderly, otherwise healthy subjects.
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brain Iron Deposits are associated with general cognitive ability and cognitive aging
Neurobiology of Aging, 2012Co-Authors: Lars Penke, Susana Munoz Maniega, Mark E Bastin, John M Starr, Ian J Deary, Maria Valdes C Hernandez, Catherine Murray, Joanna M WardlawAbstract:Abstract A novel analysis of magnetic resonance imaging (MRI) scans based on multispectral image fusion was used to quantify Iron Deposits in basal ganglia and microbleeds in 143 nondemented subjects of the generally healthy Lothian Birth Cohort, who were tested for general cognitive ability (intelligence) at mean ages of 11, 70, and 72 years. Possessing more Iron Deposits at age 72 was significantly associated with lower general cognitive ability at age 11, 70, and 72, explaining 4% to 9% of the variance. The relationships with old age general cognitive ability remained significant after controlling for childhood cognition, suggesting that Iron Deposits are related to lifetime cognitive decline. Most Iron Deposits were in the basal ganglia, with few microbleeds. While Iron Deposits in the general population have so far been dismissed in the literature, our results show substantial associations with cognitive functioning. The pattern of results suggests that Iron Deposits are not only a biomarker of general cognitive ability in old age and age-related cognitive decline, but that they are also related to the lifelong-stable trait of intelligence.
M Santosh - One of the best experts on this subject based on the ideXlab platform.
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Ordovician volcano–sedimentary Iron Deposits of the Eastern Tianshan area, Northwest China: the Tianhu example
International Geology Review, 2016Co-Authors: Chang-zhi Wu, M Santosh, Lian-xing GuAbstract:ABSTRACTThe stratabound Tianhu Iron deposit, with a reserve of 104 Mt at 42% Fe, is located in the eastern part of the Central Tianshan zone in the southern part of the Central Asian Orogenic Belt. The deposit hosts schist, quartzite, marble, amphibolite, and granitic gneiss belonging to the Tianhu Group. Laser ablation inductively coupled plasma mass spectrometry was used to perform zircon U–Pb geochronology, bulk-rock geochemistry, and in situ zircon Hf isotope analyses of the metavolcanic host rocks for constraining the timing and genesis of the Tianhu Iron deposit. According to the newly determined age constraints of 452 ± 3 and 477 ± 4 Ma, the Iron deposit was concluded to be Ordovician in age. Geochemistry and zircon Lu–Hf isotope analyses suggested that the host rocks of the deposit represent metamorphosed arc-type volcanic rocks generated by the partial melting of a lower crustal source. Combined with geological and ore petrographic characteristics, the Tianhu Iron deposit is interpreted to be of ...
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mineral chemistry of high mg diorites and skarn in the han xing Iron Deposits of south taihang mountains china constraints on mineralization process
Ore Geology Reviews, 2015Co-Authors: M Santosh, Juquan Zhang, Shengrong Li, Jizhong Wang, Qing LiAbstract:Abstract The Han-Xing region is located in the south Taihang Mountains (TM) in the central part of the North China Craton, and is an important Iron producing area. The Iron Deposits in this region are of skarn type, related to an Early Cretaceous high-Mg diorite complex, including gabbro diorite, hornblende diorite, diorite, diorite porphyrite, and monzonite. In this study we report the detailed mineral chemistry of the high-Mg diorites and skarn rocks. The olivine in the gabbro diorite shows chemical composition similar to that in mantle peridotite xenoliths. Clinopyroxene in the gabbro diorite is dominantly augite, with only minor diopside, whereas the clinopyroxenes in the diorite and monzonite are diopside. Amphiboles in the high-Mg diorites show compositional range from magnesiohornblende to magnesiohastingsite, with minor pargasite and tschermakite. Most plagioclase in the high-Mg diorite is andesine and oligoclase. The magnesio-biotite in gabbro diorites shows chemical characteristics of re-equilibrated primary biotites and those in calc-alkaline rocks. In the diorite and diorite porphyrite, plagioclase shows complex chemical zoning. Clinopyroxene and garnet in skarn rocks show varying FeO contents, the former containing low FeO ( 25 wt.%) content. We computed the pressure, temperature, oxygen fugacity and water contents based on the mineral chemistry of amphibole and biotite. Based on the results, the magma crystallization can be divided into two stages, one within the deep magma chamber, forming clinopyroxene, amphibole and plagioclase phenocrysts; the other after emplacement, forming the rim of phenocrysts and matrix minerals. The magma during the early stage shows high temperature (~ 900 °C–950 °C), pressure (~ 300 MPa–500 MPa), relatively high logfO 2 (NNO–NNO + 2), and H 2 O content in melt (4%–8%). During the late stage, the magma temperature dropped to about 750 °C, and pressure came down to less than 100 MPa, with the logfO 2 rising to NNO + 1–NNO + 2. The zoning of amphibole and plagioclase records the process of magma mixing and crystallization, with injection of mafic magma into the felsic magma chamber. The relatively high logfO 2 and H 2 O content inhibited partitioning of Iron into mafic minerals and favored concentration of Fe in the melt. Iron ore precipitation occurred when the magma was emplaced at shallow level, and was principally controlled by the chemical composition of carbonate wall rocks. The high logfO 2 , Fe 3 + rich ore-forming fluid generated andradite and clinopyroxene when it reacted with limestone and dolomitic limestone respectively.
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chronology and geochemistry of neoarchean bif type Iron Deposits in the yinshan block north china craton implications for oceanic ridge subduction
Ore Geology Reviews, 2014Co-Authors: M SantoshAbstract:Abstract The Dongwufenzi Iron deposit is a typical Algoma-type Banded Iron Formation (BIF) in the Yinshan block of the North China Craton. The Iron orebodies occur as layers interlayered with plagioclase amphibolite. LA–ICP-MS U–Pb dating of zircons from the plagioclase amphibolite yielded protolith crystallization age of 2538 ± 9 Ma (MSWD = 1.01), followed by metamorphism at 2452 ± 7 Ma (MSWD = 0.68). The geochemical characteristics of the ores including low Al 2 O 3 , TiO 2 and HFSE contents, pronounced positive Eu anomalies, and the Y/Ho ratios (26–37) suggest that the BIFs precipitated from hydrothermal fluids discharged on the seafloor. The geochemical features of the plagioclase amphibolite suggest the protolith magma to be high-Fe basalt. Sm–Nd analyses of the plagioclase amphibolite yielded eNd t (t = 2.54 Ga) and single-stage depleted mantle Nd model ages (T DM ) in the range of ca. + 1.8 to + 3.0 and 2.68 to 2.81 Ga, respectively, suggesting an enriched mantle source. We link the source of Fe in the BIFs to the komatiitic complex in the same greenstone belt, and the source of Si with the high-Fe basalt. Integrated geochronological and geochemical data from the other Archean rocks in this area suggest that the Dongwufenzi BIF formed at 2.5 Ga, coeval with the other BIFs in the North China Craton (NCC) as well as similar occurrences in other parts of the world. We propose a geodynamic model involving ridge subduction and slab window for the formation of the BIFs and the associated rock suites in the greenstone belt.
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spatio temporal distribution and tectonic settings of the major Iron Deposits in china an overview
Ore Geology Reviews, 2014Co-Authors: Zhaochong Zhang, Hou-min Li, Zuoheng Zhang, M Santosh, Jianwei Li, Xieyan Song, Meng WangAbstract:Abstract China has a rich reserve of Iron ores and hosts most of the major types of Iron Deposits recognized worldwide. However, among these, the banded Iron formation (BIF), skarn, apatite–magnetite, volcanic-hosted, sedimentary hematite and magmatic Ti–Fe–(V) Deposits constitute the most economically important types. High-grade Iron ores (> 50% Fe) are relatively rare, and are mostly represented by the skarn-type. Most of the BIF Deposits formed in the Neoarchean, with a peak at ~ 2.5 Ga, and are mainly distributed in the North China Craton. The majority of these is associated with volcanic rocks, and therefore belongs to the Algoma-type. The superior-type BIF Deposits formed during the Paleoproterozoic occur subordinately (ca. 25%), and are related mainly to rifts (or passive continental margins). In addition, minor Superior-type BIF Deposits have also been recognized. The skarn Iron Deposits are widely distributed in China, especially in the uplifted areas of eastern China, and form several large Iron ore clusters. These ore Deposits are genetically associated with intermediate, intermediate-felsic and felsic intrusions with a peak age of formation at ca. 130 Ma. They display common characteristics including alteration and nature of mineralization. The apatite–magnetite Deposits occurring in the Ningwu and Luzong Cretaceous terrigenous volcanic basins along the Middle–Lower Yangtze River Valley, are spatially and temporally associated with dioritic subvolcanic intrusions. The ores in this type are characterized by magnetite and apatite. The volcanic-hosted Iron Deposits are associated with submarine volcanic-sedimentary sequences, and are widely distributed in the orogenic belts of western China, including Western Tianshan, Eastern Tianshan, Beishan, Altay, Kaladawan area in the eastern part of the Altyn Tagh Mountain and southwestern margin of South China Block. These Deposits show a considerable age range, from Proterozoic to Mesozoic, but with more than 70% were formed in the Paleozoic, especially during the Late Paleozoic. The metallogenesis in these Deposits can be correlated to the space–time evolution of the submarine volcanism, and their relationship to volcanic lithofacies variation, such as central, proximal and distal envIronments of ore formation. The sedimentary hematite Deposits are widespread in China, among which the “Xuanlong-type” in the North China Craton and the “Ningxiang-type” in the South China Block are the most economically important. All these Deposits formed during transgressions in a shallow-marine envIronment. Magmatic Ti–Fe–(V) Deposits are dominantly distributed in the Panxi area in Sichuan province and Chengde area in Hebei province. They are dominated low-grade disseminated ores, and unlike the other types of Iron Deposits, associated sulfide Deposits are absent, with magnetite, titanomagnetite and ilmenite as the dominant ore minerals. In the Panxi area in the central Emeishan large igneous province along the western margin of South China Block, the ores are hosted in the ca. 260 Ma mafic layered intrusions, whereas the ores in the Chengde area are associated with the Mesoproterozoic anorthosite complex. The distinct spatio-temporal characteristics of the various Iron Deposits in China correlate with the multiple tectono-magmatic events associated with the prolonged geological history of the region involving accretion, assembly and rifting.