Changes in the Aging Brain
Thursday 23 April 2009
Room 311 13:30-15:30

Moderators:

 Dorothee P. Auer and Matilde Inglese
 
13:30 669. Quantification of the Healthy Human Uncinate Fasciculus Across the Lifespan Using Diffusion Tensor Tractography
    Khader M. Hasan1, Arash Kamali2, Amal Iftikhar1, Larry A. Kramer3, Paul T. Cirino4, Andrew C. Papnicolaou5, Jack M. Fletcher6, Linda Ewing-Cobbs7
1Diagnostic and Interventional Imaging, University of Texas Health Science Center at Houston, Houston, TX, USA; 2Diagnostic and Interventional Imaging, University of Texas Health Science Center at Hosuton, Houston, TX, USA; 3Diagnostic and Interventional Imaging, University of Texas Health Science Center at Houston, Hosuton, TX, USA; 4Psychology, University of Houston, Houston, TX; 5Pediatarics, University of Texas Health Science Center at Houston, Houston, TX, USA; 6Psychology, University of Texas Health Science Center at Hosuton, Houston, TX, USA; 7Pediatrics, University of Texas Health Science Center at Houston, Houston, TX, USA
    The human uncinate fasciculus (UF) is the largest cortico-cortical white matter pathway that connects directly the frontal and temporal lobes. The UF has been used in noninvasive magnetic resonance imaging (MRI) studies as a marker of tissue integrity in health and disease. There is no MRI literature on the normative UF volumetry and corresponding diffusion tensor imaging (DTI) metrics and their interplay with covariates such as age, gender and lateralization across the human lifespan. In this work, we examined using DT fiber tractography the UF volume and normalized volume with respect to each subject’s intracranial volume (ICV) and the corresponding DTI metrics bilaterally on a cohort of 108 right-handed children and adults aged 7-68 years. Our results provide the normative age, gender and laterality baseline to help in the interpretation of data from patients. Our DTI results on the development and aging of the UF consolidate previous normative studies that reported linear age trends on children and adults.
     
13:42 670. Diffusion Tensor Tractography of Corpus Callosum Development Across the Lifespan
    Saul Caverhill-Godkewitsch1, Catherine Lebel1, Christian Beaulieu1
1Biomedical Engineering, University of Alberta, Edmonton, Alberta, Canada
    Throughout life, brain changes occur, including in the corpus callosum (CC). Previous DTI studies used region-of-interest analysis on a mid-sagittal slice to study CC development, but it has not been examined with tractography. We used tractography to segment the CC based on seven distinct target regions, and examined development in 313 healthy subjects aged 5-59 years. Fractional anisotropy (FA) and mean diffusivity (MD) followed quadratic trajectories, with FA increasing then decreasing and MD following an opposite trend; peaks occurred between 26-44 years. A pattern was observed in which anterior and posterior regions peaked earlier than central areas.
     
13:54 671. Age and Gender Related Changes in DTI Metrics in Deep Grey Matter of Normal Human Brain
    Deepa Pal1, Abhishek Yadav1, Ram K.S. Rathore2, Chandra Mohan Pandey3, Manoj Kumar1, Richa Trivedi1, Rakesh K. Gupta1
1Department of Radiodiagnosis, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow, Uttar Pradesh, India; 2Department of Mathematics and Statistics, Indian Institute of Technology, Kanpur, India; 3Department of Biostatistics, Sanjay Gandhi Post Graduate Institute of Medical Science, Lucknow, UP, India
    Diffusion tensor imaging was performed on 125 healthy volunteers ranged from 10 days to 52 years. In which 50 subjects were female and rest of 75 were males. For the purpose of DTI quantitation region of interests (ROI)s were placed on deep grey nuclei (i.e. caudate nuclei, putamen and globus pallidus at the level of third ventricle) in all subjects. Increase in FA along with decrease in MD values was observed as a function of age in all of the deep grey nuclei. We observed higher FA values in all regions in males compared to females. Age related increase in FA values in grey matter suggest increased iron accumulation that occurs during the normal course of ageing. This normative data may help in early detection of neuronal degeneration associated with iron metabolism in future.
     
14:06 672. Atlas-Based Analysis of Neurodevelopment from Infancy to Adulthood Using Diffusion Tensor Imaging
    Andreia Vasconcellos Faria1,2, Jiangyang Zhang1, Kenishi Oishi1, Xin Li3, Hangyi Jiang1, Kazi Akhter1, Koji Sakai1, Laurent Hermoye4, Seung-Koo Lee5, Michael I. Miller6, Peter van Zijl1,3, Susumu Mori1
1Radiology, Johns Hopkins Medical Institutes, Baltimore, MD, USA; 2Radiology, State University of Campinas, Campinas, SP, Brazil; 3Kennedy Krieger Institute, Baltimore, MD, USA; 4Université Catholique de Louvain, Belgium; 5Yonsei University, Seoul, Korea; 6Center for Imaging Studies, Johns Hopkins University, Baltimore, MD, USA
    Quantification of normal brain maturation is a crucial step to understand developmental abnormalities. Using a nonlinear warping algorithm based on large deformation, diffeomorphic metric mapping (LDDMM) we registered Diffusion Tensor Images (DTI) of normal pediatric participants into common coordinates. The recently established brain atlas was used to automatically segment the brains which enabled us to investigate differences in maturation in different regions. Each segmented area showed distinctive maturation processes in term of its size, FA, and diffusivity. These tools and data provide information about normal values, essential for experimental designs for future pathological studies.
     
14:18 673. Relationship Between Brain R2 and Liver and Serum Iron Concentrations in Elderly Men
    Michael John House1, Timothy St. Pierre1, John Olynyk2, Elizabeth Milward3, David Bruce2
1School of Physics, The University of Western Australia, Crawley, Western Australia, Australia; 2School of Medicine and Pharmacology, The University of Western Australia, Crawley, Western Australia, Australia; 3School of Biomedical Sciences, The University of Newcastle, Newcastle, New South Wales, Australia
    Studies of iron overload in humans and animals suggest that brain iron concentrations may be related to body iron status. To evaluate this, we used MRI to measure the proton transverse relaxation rate (R2) in the brains of 20 healthy elderly men. Brain R2 values were compared with liver iron concentrations (LIC) and serum iron indices. R2 values in the globus pallidus and ventral pallidum were significantly correlated with LIC, serum iron concentrations and transferrin saturation. Our results suggest that iron levels in specific grey matter brain regions are influenced by systemic iron status in elderly men.
     
14:30 674. In Vivo Estimates of Regional Iron Deposition in Young and Elderly Human Brains
    Adolf Pfefferbaum1,2, Elfar Adalsteinsson3,4, Torsten Rohlfing1, Edith Sullivan2
1Neuroscience Program, SRI International, Menlo Park, CA, USA; 2Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, CA, USA; 3Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA; 4Harvard-MIT Division of Health Sciences & Technology, Massachusetts Institute of Technology, Cambridge, CA, USA
    Different brain structures accumulate iron at different rates throughout aging. Brain iron can be measured by estimating the relaxivity increase from 1.5T to 3.0T - MR Field Dependent R2 Increase (FDRI). Local iron influence on MR phase forms the basis for Susceptibility-Weighted Imaging (SWI) and requires imaging at only one field strength. We showed that both methods detect high globus pallidus iron concentration regardless of age and significantly greater iron in putamen with advancing age. While FDRI requires more imaging time, two field strengths, and across-study image registration for iron concentration calculation, FDRI is more specific to iron than SWI.
     
14:42 675. Increased Metabolic Stress with Aging
    Feng Xu1, Andrew Hebrank2, Uma Yezhuvath1, Daren Denniston3, Sherwood Brown3, Denise C. Park2, Hanzhang Lu1
1Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, USA; 2Center for Brain Health, University of Texas at Dallas, Dallas, TX, USA; 3Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, USA
    The balance of oxygen delivery and consumption represents an important homeostasis of brain physiology. Venous oxygenation is a useful marker for this balance. A lower venous oxygenation usually indicates that the delivery cannot keep up with the consumption. Here we used a recently developed T2-relaxation-under–spin-tagging (TRUST) MRI technique to assess venous oxygenation as a function of age. The data suggest that the venous oxygenation shows a small but significant decrease with age. The CBF shows a decrease at a similar rate, but the whole brain oxygen metabolic rate did not show a reduction.
     
14:54 676. Differential Patterns of Age-Related Changes in Cerebral Blood Flow and Cerebrovascular Reactivity Across the Lifespan
    Hanzhang Lu1, Yamei Cheng1, Andrew Hebrank2, Blair Flicker2, Uma S. Yezhuvath1, Karen Rodrigue2, Kristen Kennedy2, Denise C. Park2
1Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, USA; 2Center for Brain Health, University of Texas at Dallas, Dallas, TX, USA
    Aging of the brain is often accompanied by changes in cerebral vasculature. Here we compared the age-related decline in cerebral blood flow (CBF) and cerebrovascular reactivity (CVR). It was found that CBF deficits occur mainly in frontal lobe and anterior cingulate cortex, whereas the CVR decline involves more areas in the brain, including parietal, temporal and frontal lobes. It was concluded that the differential spatial and temporal patterns of CBF and CVR changes during aging can be explained by their sensitivity to different brain processes (CBF to neural metabolism, CVR to vessel integrity).
     
15:06 677. Bolus-Tracking Arterial Spin Labeling; a New Marker for Age and Age Related Neurological Diseases
    Michael Edward Kelly1, Christoph Wolfgang Blau2, Ranya Bechara2, Marina Anne Lynch2, Christian Mattheis Kerskens2
1Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin , Ireland; 2Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin, Ireland
    Arterial spin labeling (ASL) can be used to provide a quantitative assessment of cerebral perfusion. A new model based on a Fokker-Planck equation that reduces the number of variables required to describe the physiological processes involved is presented. Mean and capillary transit times (MTT and CTT) are calculated by fitting the model to ASL data. To test the hypothesis that these parameters vary under varying physiological conditions, a study was carried out in groups of rats of different ages. A significant difference in MTT and CTT was identified between an aged group and young and middle aged groups.
     
15:18 678. The Impact of Aging and Gender on Cerebral Viscoelasticity
    Ingolf Sack1, Bernd Beierbach1, Jens Wuerfel2, Uwe Hamhaber3, Dieter Klatt1, Sebastian Papazoglou1, Peter Martus4, Braun Juergen3
1Department of Radiology, Charité - University Medicine Berlin, Berlin, Germany; 2Department of Neuroradiology, University Lübeck, Lübeck, Schleswig-Holstein, Germany; 3Institute of Medical Informatics, Charité - University Medicine Berlin, Berlin, Germany; 4Institute of Biometry and Epidemiology, Charité - University Medicine Berlin, Berlin, Germany
    Multifrequency magnetic resonance elastography was used to investigate the in vivo viscoelasticity of healthy human brain in 55 volunteers ranging in age from 18 to 88 years. The application of four vibration frequencies in an acoustic range from 25 to 62.5 Hz revealed for the first time how physiological aging changes the global viscoelasticity of the brain. It is shown that the healthy adult brain undergoes steady parenchymal ‘liquefaction’ characterized by a continuous decline in viscoelasticity (0.8% per year, P<0.001). Furthermore, significant sex differences were found with female brains being on average 9% more viscoelastic than their male counterparts (P=0.016).