Morphometric measurements of the thalamus and interthalamic adhesion by MRI in the South-East of the Caspian Sea border

Objectives: To assess the gender differences and the age-related morphometrical changes of the thalamus, interthalamic adhesion, and the right-left differences of the thalamus of the native Fars ethnic group in the South-East of the Caspian Sea border Methods: This descriptive study was carried out on 97 patients (44 males and 53 females) without neuropathologic changes and symptoms admitted to the Kowsar MRI center in the South-East of the Caspian Sea border (Gorgan City, Northern Iran) in 2006. Thalamic dimensions were measured by MR images. The vertical lengths of the thalami and interthalamic adhesion were measured in the coronal sections, while the anteroposterior and transverse length measurements of the thalami and interthalamic adhesion were obtained in the axial plane. The data were assessed by SPSS 11.5 statistics program. Results: Thalamic dimensions were longer in males. There was no significant correlation between size of thalamus and interthalamic adhesion regarding age; however, we found that thalamic dimensions increase a little with age until the 31-40 years group, and decreased after that. There was no correlation between age and gender groups and dimensions of the interthalamic adhesion. Conclusion: This study showed that there are no significant differences between right and left sides of the thalamus, however, the left-side thalamic dimensions were a little longer than the right

A Cross-Sectional, Multi-Site Study of T1 Weighted Magnetic Resonance Image Properties

Cross sectional Magnetic Resonance Imaging (MRI) studies of the human brain have shown age related changes in morphometric measures as well as signal properties like tissue contrast. Greater access to open data sets and an emphasis on multicenter studies make repeatability of measures important. This study takes a novel dataset and MRI from the IXI open dataset to examine age related changes in MRI signal properties across sites. We processed T1 weighted MRIs of 1131 subjects from 3 sites using established tissue segmentation tools and region of interest sampling techniques to get regional and global estimates of signal intensity and volume. Signal intensity estimates were used to calculate gray-white contrast values. We created multiple linear regression models of the age related changes in gray-white contrast, within tissue coefficient of variation (CV), and tissue volume while controlling for the effects of gender and site. In addition we compared the contrast results computed using our method to the recent methods provided with FreeSurfer. Signal intensity decreased with age in two sites while increasing with age in the third. Gray-white contrast showed a decline with age in most regions across all sites. CV increased with age across all regions, sites and tissue types. GM and WM volume decreases with age globally and regionally while CSF volume increased with age. The three methods show strong proportional bias and poor agreement. It is problematic to make inferences about MRI signal intensity without first normalizing the result. Measures of contrast and CV are both normalized views of signal intensity and both show similar if inverse relationships with age. Volume changes seen here are in agreement with previously published results, but the rates differ by site. Normalizing volume measurements by inter-cranial volume removes the site-specific rate differences. While the gray-white contrast calculation methods show strong correlation, the estimates are not comparable. Age related MRI signal property changes exist and may affect morphometric measurements. The public health relevance of this research relates to the possibility that MRI contrast may be a biomarker for use in diagnosing neurodegenerative diseases like Alzheimer’s that affect elderly populations allowing earlier detection and treatment

Computational analysis reveals increased blood deposition following repeated mild traumatic brain injury.

Mild traumatic brain injury (mTBI) has become an increasing public health concern as subsequent injuries can exacerbate existing neuropathology and result in neurological deficits. This study investigated the temporal development of cortical lesions using magnetic resonance imaging (MRI) to assess two mTBIs delivered to opposite cortical hemispheres. The controlled cortical impact model was used to produce an initial mTBI on the right cortex followed by a second injury induced on the left cortex at 3 (rmTBI 3d) or 7 (rmTBI 7d) days later. Histogram analysis was combined with a novel semi-automated computational approach to perform a voxel-wise examination of extravascular blood and edema volumes within the lesion. Examination of lesion volume 1d post last injury revealed increased tissue abnormalities within rmTBI 7d animals compared to other groups, particularly at the site of the second impact. Histogram analysis of lesion T2 values suggested increased edematous tissue within the rmTBI 3d group and elevated blood deposition in the rm TBI 7d animals. Further quantification of lesion composition for blood and edema containing voxels supported our histogram findings, with increased edema at the site of second impact in rmTBI 3d animals and elevated blood deposition in the rmTBI 7d group at the site of the first injury. Histological measurements revealed spatial overlap of regions containing blood deposition and microglial activation within the cortices of all animals. In conclusion, our findings suggest that there is a window of tissue vulnerability where a second distant mTBI, induced 7d after an initial injury, exacerbates tissue abnormalities consistent with hemorrhagic progression

Characterizing aging in the human brainstem using quantitative multimodal MRI analysis.

Aging is ubiquitous to the human condition. The MRI correlates of healthy aging have been extensively investigated using a range of modalities, including volumetric MRI, quantitative MRI (qMRI), and diffusion tensor imaging. Despite this, the reported brainstem related changes remain sparse. This is, in part, due to the technical and methodological limitations in quantitatively assessing and statistically analyzing this region. By utilizing a new method of brainstem segmentation, a large cohort of 100 healthy adults were assessed in this study for the effects of aging within the human brainstem in vivo. Using qMRI, tensor-based morphometry (TBM), and voxel-based quantification (VBQ), the volumetric and quantitative changes across healthy adults between 19 and 75 years were characterized. In addition to the increased R2* in substantia nigra corresponding to increasing iron deposition with age, several novel findings were reported in the current study. These include selective volumetric loss of the brachium conjunctivum, with a corresponding decrease in magnetization transfer and increase in proton density (PD), accounting for the previously described “midbrain shrinkage.” Additionally, we found increases in R1 and PD in several pontine and medullary structures. We consider these changes in the context of well-characterized, functional age-related changes, and propose potential biophysical mechanisms. This study provides detailed quantitative analysis of the internal architecture of the brainstem and provides a baseline for further studies of neurodegenerative diseases that are characterized by early, pre-clinical involvement of the brainstem, such as Parkinson’s and Alzheimer’s diseases

The morphometric measurement of the brain stem in Turkish healthy subjects according to age and sex

Background: This paper determined the morphometric measurements of the brainstem including mesencephalon, pons and medulla using magnetic resonance imaging (MRI) in Turkish healthy population. Materials and methods: Two hundred sixty-three (263; 158 females and 105 males) subjects aged from 18 to 65 years were included in this study. The measurements were taken from subjects having brain MRI in the Radiology Department. Statistical analysis was done by SPSS 21.00 package programme. ANOVA test and χ2 test were used to determine the relation between measurements and age and sex groups. The p < 0.05 value was considered as significant. Results: The overall means and standard deviations of the measurements were: pons anteroposterior diameter, 15.41 ± 1.27 mm; pons vertical diameter, 22.02 ± 2.07 mm; mesencephalon anteroposterior diameter 9.39 ± 1.00 mm; mesencephalon vertical diameter, 15.20 ± 1.53 mm; distance between the interpeduncular fissure and aqueduct, 11.72 ± 1.58 mm; distance from cerebral peduncles to aqueduct, 13.64 ± 1.66 mm; anterior surface of the pons midway between the mesencephalon and medulla to the fourth ventricular floor, 21.62 ± 1.64 mm; the shortest anteroposterior diameter of the medulla at the pontomedullary junction, 13.46 ± 1.28 mm, and the shortest anteroposterior diameter of the medulla at the medullospinal junction, 10.24 ± 1.43 mm in females, respectively, whereas the corresponding values were 15.58 ± 1.53 mm; 22.64 ± 2.35 mm; 9.37 ± 1.66 mm; 15.64 ± 1.52 mm; 11.14 ± 1.31 mm; 13.01 ± 1.30 mm; 21.97 ± 1.65 mm;13.47 ± 1.19 mm; 9.91 ± 1.35 mm in males, respectively. There were significant differences in some parameters such as pons vertical diameter, mesencephalon vertical diameter, distance between the interpeduncular fissure and aqueduct, and distance between cerebral peduncles to aqueduct between sexes. Conclusions: The brainstem dimensions of healthy population provide important and useful knowledge in terms of comparison of abnormalities clinically. These data may be valuable for the representatives of clinical disciplines

Mediterranean-type diet and brain structural change from 73 to 76 years in a Scottish cohort

STUDY FUNDING The data were collected by a Research into Ageing programme grant; research continues as part of the Age UK–funded Disconnected Mind project. The work was undertaken by The University of Edinburgh Centre for Cognitive Ageing and Cognitive Epidemiology, part of the cross-council Lifelong Health and Wellbeing Initiative (MR/K026992/1), with funding from the BBSRC and Medical Research Council. Imaging and image analysis was performed at the Brain Research Imaging Centre (sbirc.ed.ac.uk/), Edinburgh, supported by the Scottish Funding Council SINAPSE Collaboration. Derivation of mean cortical thickness measures was funded by the Scottish Funding Council’s Postdoctoral and Early Career Researchers Exchange Fund awarded by SINAPSE to David Alexander Dickie. L.C.A.C. acknowledges funding from the Scottish Government's Rural and Environment Science and Analytical Services (RESAS) division.Peer reviewedPublisher PD

Investigation of the Safety of Focused Ultrasound-Induced Blood-Brain Barrier Opening in a Natural Canine Model of Aging

Rationale: Ultrasound-mediated opening of the Blood-Brain Barrier(BBB) has shown exciting potential for the treatment of Alzheimer\u27s disease(AD). Studies in transgenic mouse models have shown that this approach can reduce plaque pathology and improve spatial memory. Before clinical translation can occur the safety of the method needs to be tested in a larger brain that allows lower frequencies be used to treat larger tissue volumes, simulating clinical situations. Here we investigate the safety of opening the BBB in half of the brain in a large aged animal model with naturally occurring amyloid deposits. Methods: Aged dogs naturally accumulate plaques and show associated cognitive declines. Low-frequency ultrasound was used to open the BBB unilaterally in aged beagles (9-11yrs, n=10) in accordance with institutionally approved protocols. Animals received either a single treatment or four weekly treatments. Magnetic resonance imaging(MRI) was used to guide the treatments and assess the tissue effects. The animals underwent neurological testing during treatment follow-up, and a follow-up MRI exam 1 week following the final treatment. Results: The permeability of the BBB was successfully increased in all animals (mean enhancement: 19±11% relative to untreated hemisphere). There was a single adverse event in the chronic treatment group that resolved within 24 hrs. Follow-up MRI showed the BBB to be intact with no evidence of tissue damage in all animals. Histological analysis showed comparable levels of microhemorrhage between the treated and control hemispheres in the prefrontal cortex (single/repeat treatment: 1.0±1.4 vs 0.4±0.5/5.2±1.8 vs. 4.0±2.0). No significant differences were observed in beta-amyloid load (single/repeat: p=0.31/p=0.98) although 3/5 animals in each group showed lower Aβ loads in the treated hemisphere. Conclusion: Whole-hemisphere opening of the BBB was well tolerated in the aged large animal brain. The treatment volumes and frequencies used are clinically relevant and indicate safety for clinical translation. Further study is warranted to determine if FUS has positive effects on naturally occurring amyloid pathology

MRI Parameters Of Alzheimer's Disease in an Arab Population of Wadi Ara, Israel

Magnetic resonance imaging (MRI) findings are reported from 15 individuals in an Arab–Israeli community who were diagnosed with Alzheimer's disease (AD). The quantitative parameters that were used for MRI analyses included gradings (0–3) and linear measurements of different brain structures. Generalized tissue loss was assessed by combined measurements of the ventricles (ventricular score, VS) and sulcal grading and width (SG, SW, respectively). Loss of brain tissue in specific regions of interest, eg, temporal lobes, basal ganglia, and midbrain, was evaluated by precise measurements. We observed abnormal tissue characteristics, expressed as high intensity foci in white matter on T2W sequences, as well as tissue loss, both generalized and focal. Most notable were changes involving the head of the caudate nuclei, the midbrain, and to a lesser degree, medial temporal structures.National Institute of Aging (UO1-AG17173); National Institute on Alcohol Abuse and Alcoholism (R37-AA07112, K05-AA00219); US Department of Veterans Affair

Respiratory challenge MRI: practical aspects

Respiratory challenge MRI is the modification of arterial oxygen (PaO2) and/or carbon dioxide (PaCO2) concentration to induce a change in cerebral function or metabolism which is then measured by MRI. Alterations in arterial gas concentrations can lead to profound changes in cerebral haemodynamics which can be studied using a variety of MRI sequences. Whilst such experiments may provide a wealth of information, conducting them can be complex and challenging. In this paper we review the rationale for respiratory challenge MRI including the effects of oxygen and carbon dioxide on the cerebral circulation. We also discuss the planning, equipment, monitoring and techniques that have been used to undertake these experiments. We finally propose some recommendations in this evolving area for conducting these experiments to enhance data quality and comparison between techniques