Cerebral Blood Flow in Relation to Contralateral Carotid Disease an MRA and TCD Study

AbstractObjective: to describe redistribution of cerebral blood flow in patients with severe internal carotid artery (ICA) stenoses in relation to contralateral ICA disease. Methods: sixty-six patients scheduled for carotid endarterectomy (CEA) were grouped according to severity of contralateral stenosis (<30% [group I]; 30–69% [group II]; 70–99% [group III]; occlusion [group IV]. Transcranial Doppler (TCD) and magnetic resonance angiography (MRA) investigations were performed preoperatively. Results: TCD demonstrated a reversed flow in the contralateral anterior cerebral artery (A1segment) and ophthalmic artery in three-quarters of group IV patients (p <0.0001). Group IV patients also exhibited decreased blood flow velocity in the contralateral middle cerebral artery (p =0.001). MRA showed increased ipsilateral ICA and basilar artery (BA) blood flow volumes (Q-flows) in group IV patients when compared to the other groups (p <0.001). No changes in total Q-flow (ICAs+BA) were found. Conclusions: in patients considered for CEA, the severity of the contralateral ICA disease is an important determinant of the pattern of blood flow redistribution through the anterior communicating pathway and ophthalmic artery. Significant flow redistribution through the posterior communicating pathway occurs especially in patients with contralateral ICA occlusion

The cinepheur: post-cinematic passage, post-perceptual passage

This thesis develops a hermeneutic commensurate with the aesthetic and ontological challenges of what Steven Shaviro describes as a post-cinematic media ecology, and Shane Denson describes as an emergent post-perceptual media ecology. I consider canonicity and cinephilia as frustrated efforts to contain and comprehend this new cinematic media object, offering a third unit of interpretation in their place, which I describe as the cinetopic anecdote. I associate the cinetopic anecdote with a particular way of moving between cinema and cinematic infrastructure, which I label cinetopic passage, and with a subject position that I label the cinepheur. Drawing on Walter Benjamin’s theory of the flâneur, I argue that the cinetopic anecdote precludes the extraction of a privileged cinematic moment in the manner characteristic of Christian Keathley’s cinephilic anecdote, but instead compels the cinepheur to instantiate, embody or physically recreate the infrastructural conditions that produced it, dovetailing production and consumption into what Axel Bruns has described as the emergent category of produsage; “unfinished artifacts, continuing process.” Having elaborated the cinetopic anecdote, I apply it to postmodern, post-cinematic and post-perceptual media ecologies, in order to evoke the peculiar forms of attachment and obsession bound up with the Criterion and Netflix platforms. In the process, I draw on Franco Moretti’s conception of distant reading to frame the cinetopic anecdote as a unit of distant viewing, offering distant viewings of Angela Christlieb and Stephen Kijak’s Cinemania, Sidney Lumet’s Garbo Talks and Pier Paolo Pasolini’s Salò, or The 120 Days of Sodom. Just as distant reading takes “the great unread” as its object of enquiry, so the cinetopic anecdote speaks to a media ecology preoccupied by the “great unviewed,” in which cinematic scarcity increasingly ramifies as an elegaic object

Automated measurement of brain and white matter lesion volume in type 2 diabetes mellitus

Aims/hypothesis: Type 2 diabetes mellitus has been associated with brain atrophy and cognitive decline, but the association with ischaemic white matter lesions is unclear. Previous neuroimaging studies have mainly used semiquantitative rating scales to measure atrophy and white matter lesions (WMLs). In this study we used an automated segmentation technique to investigate the association of type 2 diabetes, several diabetes-related risk factors and cognition with cerebral tissue and WML volumes. Subjects and methods: Magnetic resonance images of 99 patients with type 2 diabetes and 46 control participants from a population-based sample were segmented using a k-nearest neighbour classifier trained on ten manually segmented data sets. White matter, grey matter, lateral ventricles, cerebrospinal fluid not including lateral ventricles, and WML volumes were assessed. Analyses were adjusted for age, sex, level of education and intracranial volume. Results: Type 2 diabetes was associated with a smaller volume of grey matter (-21.8 ml; 95% CI -34.2, -9.4) and with larger lateral ventricle volume (7.1 ml; 95% CI 2.3, 12.0) and with larger white matter lesion volume (56.5%; 95% CI 4.0, 135.8), whereas white matter volume was not affected. In separate analyses for men and women, the effects of diabetes were only significant in women. Conclusions/interpretation: The combination of atrophy with larger WML volume indicates that type 2 diabetes is associated with mixed pathology in the brain. The observed sex differences were unexpected and need to be addressed in further studies. © 2007 Springer-Verlag

Loss of integrity and atrophy in cingulate structural covariance networks in Parkinson's disease

Neuro Imaging Researc

The visual cortex and visual cognition in Huntington's disease: An overview of current literature

Neuro Imaging Researc

Altered Whole-Brain and Network-Based Functional Connectivity in Parkinson's Disease

Neuro Imaging Researc

Aging effect, reproducibility, and test-retest reliability of a new cerebral amyloid angiopathy MRI severity marker-cerebrovascular reactivity to visual stimulation

Background Decreased cerebrovascular reactivity, measured as changes in blood-oxygen-level-dependent (BOLD) signal, is a potential new cerebral amyloid angiopathy (CAA) severity marker. Before clinical application, the effect of aging on BOLD parameters, and reproducibility and test-retest reliability of these parameters should be assessed. Purpose Assess the effect of healthy aging on cerebrovascular reactivity (BOLD amplitude, time to peak, and time to baseline). And determine reproducibility and test-retest reliability of these parameters. Study Type Prospective-observational. Population Eighty-six healthy adults (mean age 56 years, 55% female), 10 presymptomatic D-CAA mutation carriers (mean age 34 years, 70% female), and 10 symptomatic D-CAA mutation carriers (mean age 54 years, 70% female). Field Strength/Sequence 3-T, three-dimensional (3D) T1-weighted MRI and gradient echo BOLD fMRI. Assessment To assess test-retest reliability of BOLD parameters, i.e. BOLD amplitude, time to peak, and time to baseline, BOLD fMRI scans were repeated three times immediately after each other, in both controls and mutation carriers. To assess reproducibility, BOLD fMRI scans were repeated with a 3-week interval for each subject. Statistical Tests Linear regression analyses and two-way mixed absolute agreement intra-class correlation approach. Results Healthy aging was associated with decreased BOLD amplitude (beta = -0.711) and prolonged time to baseline (beta = 0.236) in the visual cortex after visual stimulation Reproducibility of BOLD amplitude was excellent (ICC 0.940) in the subgroup of healthy adults. Test-retest reliability for BOLD amplitude was excellent in healthy adults (ICC 0.856-0.910) and presymptomatic D-CAA mutation carriers (ICC 0.959-0.981). In symptomatic D-CAA mutation carriers, test-retest reliability was poor for all parameters (ICCs < 0.5). Data Conclusion Healthy aging is associated with decreased cerebrovascular reactivity, measured by changes in BOLD response to visual stimulation. The BOLD amplitude appears to be a robust measurement in healthy adults and presymptomatic D-CAA mutation carriers, but not in symptomatic D-CAA mutation carriers.Multivariate analysis of psychological dat

Transcriptomic signatures associated with regional cortical thickness changes in Parkinson's disease

Cortical atrophy is a common manifestation in Parkinson's disease (PD), particularly in advanced stages of the disease. To elucidate the molecular underpinnings of cortical thickness changes in PD, we performed an integrated analysis of brain-wide healthy transcriptomic data from the Allen Human Brain Atlas and patterns of cortical thickness based on T1-weighted anatomical MRI data of 149 PD patients and 369 controls. For this purpose, we used partial least squares regression to identify gene expression patterns correlated with cortical thickness changes. In addition, we identified gene expression patterns underlying the relationship between cortical thickness and clinical domains of PD. Our results show that genes whose expression in the healthy brain is associated with cortical thickness changes in PD are enriched in biological pathways related to sumoylation, regulation of mitotic cell cycle, mitochondrial translation, DNA damage responses, and ER-Golgi traffic. The associated pathways were highly related to each other and all belong to cellular maintenance mechanisms. The expression of genes within most pathways was negatively correlated with cortical thickness changes, showing higher expression in regions associated with decreased cortical thickness (atrophy). On the other hand, sumoylation pathways were positively correlated with cortical thickness changes, showing higher expression in regions with increased cortical thickness (hypertrophy). Our findings suggest that alterations in the balanced interplay of these mechanisms play a role in changes of cortical thickness in PD and possibly influence motor and cognitive functions.Neuro Imaging Researc

The progression of spermatogenesis in the developing rat testis followed by ³¹P MR spectroscopy

To evaluate the use of human testicular 31P MR spectroscopy as a diagnostic tool to differentiate between several stages of male infertility, we have studied the testicular levels of several phosphorus containing compounds in the rat in relation to the condition of spermatogenesis and the cell types present in the seminiferous tubules of the testis. During testicular maturation several characteristic changes occur in the 31P MR spectrum of the testis of male Wistar rats. The phosphomonoester/adenosine triphosphate (PM/ATP) ratio shows a decline from 1.61 to 1.02 between the age of 3 and 12 weeks, whereas the phosphodiester (PD)/ATP ratio increases from 0 to 0.72. The testicular pH increases in the same time from 7.06 to 7.32. Testicular MR data obtained after 12 weeks of age onward do not show significant change anymore. The high PM/ATP ratio is associated by a relative high amount of proliferating spermatogonia and spermatocytes during meiosis in the testis, whereas the PD peak seems to be correlated with the release and maintenance of spermatozoa. The MR spectra show a specific fingerprint in all developmental stages of the rat testis as a result of the different cell types in the testis. © 1992 Academic Press, Inc.</p

Diminished Posterior Precuneus Connectivity with the Default Mode Network Differentiates Normal Aging from Alzheimer's Disease

Multivariate analysis of psychological dat