Goals: 1) to evaluate region, sex, and age effects on Nacetyl aspartate [NAA a neuronal marker] in demented subjects and controls, 2) to determine relationships between [NAA] in hippocampus and cortex, and 3) to test the extent to which [NAA] and MRI predict dementia. MRSI and MRI studies were performed on 55 Alzheimer's disease (AD), 13subcortical ischemic vascular dementia (SIVD) patients and 54controls. In AD, marked [NAA] reductions occurred in the hippocampus and parietal cortex, while frontal cortex was spared. [NAA] reduction in SIVD occurred in both, parietal and frontal cortex, while hippocampus was spared. [NAA] differences between hippocampus and cortex were highly significant (p< 0.0001) in each group. AD and SIVD had different levels of hippocampal atrophy. Finally, a logistic regression model showed that NAA together with MRI significantly improved classification of AD and SIVD from controls. We conclude that AD and SIVD exhibit different patterns of regional [NAA] reduction, consistent with ...

Introduction: The beneficial effects of intravenous human umbilical cord blood cells (HUCBC) administration after stroke have recently been demonstrated in rodents. In addition, there is evidence for an extended time window for this experimental treatme...

INTRODUCTION: Diffusion tensor imaging (DTI), magnetization transfer (MT), and T2*-weighted (T2*w) MRI can measure micro- and macro-structural changes, including axonal loss, demyelination, and atrophy. We introduce T2*-white matter (WM)/grey matter (GM...

Deep brain stimulation (DBS) is used increasingly in the field of movement disorders. The implanted electrodes create not only a priori risk to patient safety during MR imaging, but also a unique opportunity in the collection of functional MRI (fMRI) data conditioned by direct neural stimulation. We performed safety tests of commercially available bilateral neurostimulation systems (Soletra® 7482, Medtronic), extensions, and leads in a clinical 1.5 T MR system (Siemens, Germany) across a range of MR acquisitions of typical and worst case scenarios. The primary safety risk arises from RF induction of current through the electrode leads. It depends on the RF energy deposited during specific imaging sequences, on physical properties of the electrodes, and on the low impedance and/or resonant paths within the lead geometry. In vitro testing was performed using a phantom filled with a semisolid gel simulating the thermal convection and dielectric properties of human tissues. Each DBS electrode was positioned wi...

Language function was studied in 17 patients with infarctions apparently confined to unilateral basal ganglia and surrounding white matter [10 left hemisphere (LH), 7 right hemisphere (RH)]. Mean age at injury was 7yrs and 4yrs, and mean age at study was 12yrs and 9yrs, for the LH and RH groups respectively. We have previously shown that long-term receptive and expressive language outcome did not differ significantly between the LH and RH groups. The variance in the LH group was, however, much greater than in the RH group. Voxel-based morphometric analyses of structural MRI 3D datasets and MR diffusion tensor imaging data identified regions of grey and white matter density and diffusion anisotropy, outside the site of the infarction and including Broca’s area, that correlated with language performance in the LH group but not in the RH group. Furthermore, the only 3 patients with haemodynamic abnormalities involving left cortical language areas on MR perfusion imaging were the 3 LH patients with poorest lan...

Comparisons of alterations in the anatomy of the entorhinal cortex (EC) and hippocampal formation (HF) in elderly individuals are of great interest, since these regions are pathologically involved in the very early stages of Alzheimer's disease (AD) and could, potentially, identify those at risk for developing AD. In the present study, 27 patients diagnosed with mild cognitive impairment (MCI-memory) received a high-resolution MRI scan at baseline and were followed with yearly clinical evaluations. Ten of the 27 converted to AD during a 36 month-period following the baseline clinical evaluation. EC and HF volumes were derived separately for each hemisphere from T1-weighted coronal images reformatted to be perpendicular to the long axis of the HF. To control for individual differences in brain size, regions of interest were divided by total intracranial volume (normalized). Logistic regression models showed that although both normalized entorhinal and hippocampal volumes were independent predictors of conve...

Whether conventional gradient-echo (GE) blood oxygenation-level-dependent (BOLD) functional magnetic resonance imaging (fMRI) is able to map submillimeter-scale functional columns remains debatable mainly because of the spatially nonspecific large vessel contribution, poor sensitivity and reproducibility, and lack of independent evaluation. Furthermore, if the results from optical imaging of intrinsic signals are directly applicable, regions with the highest BOLD signals may indicate neurally inactive domains rather than active columns when multiple columns are activated. To examine these issues, we performed BOLD fMRI at a magnetic field of 9.4 tesla to map orientation-selective columns of isoflurane-anesthetized cats. We could not convincingly map orientation columns using conventional block-design stimulation and differential analysis method because of large fluctuations of signals. However, we successfully obtained GE BOLD iso-orientation maps with high reproducibility ( r = 0.74) using temporally enco...

Chronic neuropathic pain can result from nervous system injury and can persist in the absence of external stimuli. Although ongoing pain characterizes the disorder, in many individuals, the intensity of this ongoing pain fluctuates dramatically. Previously, it was identified that functional magnetic resonance imaging (fMRI) signal covariations between the midbrain periaqueductal gray matter (PAG), rostral ventromedial medulla (RVM), and spinal trigeminal nucleus (SpV) are associated with moment-to-moment fluctuations in pain intensity in individuals with painful trigeminal neuropathy (PTN). Since this brainstem circuit is modulated by higher brain input, we sought to determine which cortical sites might be influencing this brainstem network during spontaneous fluctuations in pain intensity. Over 12 minutes, we recorded ongoing pain intensity in 24 PTN participants, and classified them as fluctuating (n=13) or stable (n=11). Using a PAG seed, we identified connections between the PAG and emotional-affective...

The distribution of myelin in the human brain provides a basis for the parcellation of cortex into distinct anatomical and functional subunits. in-vivo studies have shown that myeloarchitectural features such as the stria of Gennari can be found within primary visual cortex (Clark et al (1991), Barbiere et al (2002)) and that more subtle features can be detected in extrastriate cortex (Walters et al (2003). Analysis of this data usually requires time-consuming manual study to determine the boundaries between white matter and gray matter and to carry out densitometric analysis. Accurate cortical surfaces allow line density profiles to be automatically and objectively generated and analyzed. Here we present an early example of this technique on high resolution MR images acquired using an MP-RAGE sequence with occipital or flexible bi-temporal phased-array (Nova Medical). Voxel size was approximately 0.3 x 0.3 mm in plane with a slice thickness of 0.5mm-0.9mm. Cortical surfaces were computed using FreeSurfer ...

Development, aging, and neurodegenerative pathologies are known to affect medial temporal lobe (MTL) subregions differently, selectively, and in a complex progression. Characterizing MTL subregional changes using high-resolution MRI may provide greater ...