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FLAIR vascular hyperintensities are thought to represent leptomeningeal collaterals in acute ischemic stroke. However, whether all-FLAIR vascular hyperintensities or FLAIR vascular hyperintensities-DWI mismatch, ie, FLAIR vascular hyperintensities beyond the DWI lesion, best reflects collaterals remains debated. We aimed to compare the value of FLAIR vascular hyperintensities-DWI mismatch versus all-FLAIR vascular hyperintensities for collateral assessment using PWI-derived collateral flow maps as a reference.We retrospectively reviewed the registries of 6 large stroke centers and included all patients with acute stroke with anterior circulation large-vessel occlusion who underwent MR imaging with PWI before thrombectomy. Collateral status was graded from 1 to 4 on PWI-derived collateral flow maps and dichotomized into good (grades 3-4) and poor (grades 1-2). The extent of all-FLAIR vascular hyperintensities and FLAIR vascular hyperintensities-DWI mismatch was assessed on the 7 cortical ASPECTS regions, ranging from 0 (absence) to 7 (extensive), and associations with good collaterals were compared using receiver operating characteristic curves.Of the 209 included patients, 133 (64%) and 76 (36%) had good and poor collaterals, respectively. All-FLAIR vascular hyperintensity extent was similar between collateral groups (In acute ischemic stroke with large-vessel occlusion, the extent of FLAIR vascular hyperintensities does not reliably reflect collateral status unless one accounts for DWI.

Spinal hemangiomas are rare vascular malformations resulting from proliferation of vascular endothelial cells. The cavernous form is the most common and represents 5-12% of spinal vascular malformations, while the capillary form is rare.A 56-year-old patient with no past medical history presented with progressive spinal cord compression symptoms localizing to the T10 level with MRC grade 4 proximal paraparesis. Preoperative MRI demonstrated a well-delineated, dumbbell-shaped, epidural lesion, without bony involvement, resulting in spinal cord compression at the T7 and T8 levels. The patient underwent gross total surgical resection of the lesion. At the one month follow up, the patient's strength improved to MRC grade 5, and sensation had fully returned. The histopathological diagnosis was a capillary hemangioma. Exclusively epidural capillary hemangiomas are extremely rare with only 26 cases reported in the literature. They are mainly located at the thoracic level (T4-T6). The MRI features include a well-circumscribed mass, hyperintense on T2-weighted sequence in 92% of cases, isointense on T1-weighted sequence in 88% of cases, and homogeneous contrast enhancement in 100% of cases. No tumor recurrence has been observed after gross total surgical removal.When evaluating progressive spinal cord compression by a purely epidural spinal lesion, the differential diagnosis should include capillary hemangioma, in addition to schwannoma, meningioma, and lymphoma. Early and complete surgical removal is the first line treatment.

International audience; Background and purpose: Collateral status and thrombus length have been independently associated with functional outcome in patients with acute ischemic stroke. It has been suggested that thrombus length would influence functional outcome via interaction with the collateral circulation. We investigated the individual and combined effects of thrombus length assessed by the clot burden score and collateral status assessed by a FLAIR vascular hyperintensity-ASPECTS rating system on functional outcome (mRS).Materials and methods: Patients with anterior circulation acute ischemic stroke due to large-vessel occlusion from the ASTER and THRACE trials treated with endovascular thrombectomy were pooled. The clot burden score and FLAIR vascular hyperintensity score were determined on MR imaging obtained before endovascular thrombectomy. Favorable outcome was defined as an mRS score of 0-2 at 90 days. Association of the clot burden score and the FLAIR vascular hyperintensity score with favorable outcome (individual effect and interaction) was examined using logistic regression models.Results: Of the 326 patients treated by endovascular thrombectomy with both the clot burden score and FLAIR vascular hyperintensity assessment, favorable outcome was observed in 165 (51%). The rate of favorable outcome increased with clot burden score (smaller clots) and FLAIR vascular hyperintensity (better collaterals) values. The association between clot burden score and functional outcome was significantly modified by the FLAIR vascular hyperintensity score, and this association was stronger in patients with good collaterals, with an adjusted OR = 6.15 (95% CI, 1.03-36.81).Conclusions: The association between the clot burden score and functional outcome varied for different collateral scores. The FLAIR vascular hyperintensity score might be a valuable prognostic factor, especially when contrast-based vascular imaging is not available.

The prospect of widespread content mining of the scholarly literature is emerging, driven by the promise of increased permissions due to copyright reform in countries such as the UK and the support of some publishers, particularly those that publish open access-journals. In parallel, the growing software tool set for mining, and the availability of ontologies such as DBPedia mean that many scientists can start to mine the literature with relatively few technical barriers. We believe that content mining can be carried out in a responsible, legal manner causing no technical issues for any parties. In addition, ethical concerns including the need for formal accreditation and citation can be addressed, with the further possibility of machine-supported metrics. This chapter sets out some approaches to act as guidelines for those starting mining activities.

Les causes de coma dans un contexte non traumatique sont multiples : vasculaires (ischemie arterielle par occlusion de l’artere basilaire, thrombose des veines cerebrales profondes, hemorragie sous-arachnoidienne anevrismale, intoxication a la cocaine, encephalopathie posterieure et reversible), metaboliques (encephalopathie hypoglycemique, myelinolyse osmotique centropontique, encephalopathie hepatique), toxiques (intoxication au monoxyde de carbone ou au methanol, maladie de Marchiafava-Bignami, encephalopathie de Gayet-Wernicke), infectieuses, tumorales, liees a un etat de mal epileptique ou a une anoxie cerebrale. Le scanner cerebral, du fait de sa grande disponibilite et de sa rapidite d’acquisition, est le plus frequemment realise a la phase aigue. Il est souvent pris en defaut, des lors que l’origine n’est pas une hemorragie ou un processus expansif intracrânien. L’imagerie par resonance magnetique (IRM) est aujourd’hui l’examen de choix dans la prise en charge des comas non traumatiques pour le diagnostic etiologique, en raison d’une plus grande sensibilite de detection des lesions cerebrales, permettant ainsi un diagnostic plus precoce de la pathologie causale et, dans certains cas, la mise en place d’un traitement specifique.

RADIOLOGIE ET IMAGERIE MEDICALE : Musculosquelettique - Neurologique - Maxillofaciale - 31-657-A-10

RADIOLOGIE ET IMAGERIE MEDICALE : Musculosquelettique - Neurologique - Maxillofaciale - 31-644-A-10

E. F. Chinaglia*,**, and I. C. Oppenheim* *Department of Metallurgy and Materials Engineering, Escola Politecnica, Universidade de Sao Paulo, Av. Prof. Mello Moraes, 2463, Sao Paulo, SP, 05508-900, Brasil. **Shimadzu do Brasil Comercio Ltda., Av. Marques de Sao Vicente, 1771, Sao Paulo-SP, 01139-003, Brasil. e-mail: tatachi@usp.br Keywords: resistivity, surface morphology, thin films, titanium, zirconium, sputtering, atomic force microscopy, reflection coefficient, Mayadas-Shazkes Thin film morphology and electrical resistivity play an important role in modern technologies. In particular, subcomponents fabricated by Ti play an increasing role in microelectronic device technology as well as in the biomedical area [1-2]. Here the influence of substrate temperature (during deposition) and film thickness on the surface morphology and electrical resistivity of polycrystalline Ti and Zr thin films have been investigated. The well established Matthiessen’s rule, originally suggested for bulk metals, is also valid for thin metal films [3]. The rule states that the various electron scattering processes that contribute to the total electrical resistivity (ρ) of a metallic thin film do so independently and additively; i.e., ρ = ρ

Resume L'imagerie de diffusion, qui mesure les mouvements microscopiques des molecules d'eau, apporte des informations sur la physiopathologie des affections encephaliques qui ne sont pas disponibles sur les sequences conventionnelles d'imagerie par resonance magnetique (IRM). Le contraste des images de diffusion depend des differences de mobilite des molecules d'eau plutot que des modifications globales de la teneur en eau des tissus. Cette technique est tres sensible a la detection de l'ischemie arterielle cerebrale et permet de distinguer l'ischemie cerebrale des pathologies d'origine non vasculaire chez des patients presentant un deficit neurologique focal d'apparition brutale. Son champ d'application depasse aujourd'hui largement celui de la pathologie vasculaire. Integree aux autres sequences d'IRM, elle contribue tres efficacement a la distinction entre abces cerebral et tumeur necrotique, entre kyste epidermoide et kyste arachnoidien. Technique veritablement quantitative, l'imagerie de diffusion est une source d'information supplementaire pour la caracterisation des lesions tumorales, inflammatoires. Enfin, les donnees de l'imagerie de diffusion ont egalement une valeur pronostique.

We present results for the generating functions of single fully-directed walks on the triangular lattice, enumerated according to each type of step and weighted proportional to the area between the walk and the surface of a half-plane (wall), and the number of contacts made with the wall. We also give explicit formulae for total area generating functions, that is when the area is summed over all configurations with a given perimeter, and the generating function of the moments of heights above the wall (the first of which is the total area). These results generalise and summarise nearly all known results on the square lattice: all the square lattice results can be obtaining by setting one of the step weights to zero. Our results also contain as special cases those that already exist for the triangular lattice. In deriving some of the new results we utilise the Enumerating Combinatorial Objects (ECO) and marked area methods of combinatorics for obtaining functional equations in the most general cases. In several cases we give our results both in terms of ratios of infinite q-series and as continued fractions.

We present results for the generating functions of polygons and more general objects that can touch, constructed from two fully directed walks on the infinite triangular lattice, enumerated according to each type of step and weighted proportional to the area and the number of contacts between the directed sides of the objects. In general these directed objects are known as festoons, being constructed from the so-called friendly directed walks, while the subset constructed from vicious walks are staircase polygons, also known as parallelogram polyominoes. Additionally, we give explicit formulae for various first area-moment generating functions, that is when the area is summed over all configurations with a given perimeter. These results generalize and summarize nearly all known results on the square lattice, since such results can be obtained by setting one of the step weights to zero. All our results for the triangular lattice are new and hence provide the opportunity to study subtle changes in scaling between lattices. In most cases we give our results both in terms of ratios of infinite q-series and as continued fractions.

Moya-Moya disease is a rare arterial occlusive disease affecting the internal carotid artery and its branches. It is found in both pediatric and adult populations, and it may lead to severe clinical presentations such as stroke and intracranial hemorrhage. Several surgical procedures have been developed to improve its clinical outcome. Imaging techniques have a key role in management of Moya-Moya disease, as they are necessary for diagnosis, choice of treatment and follow-up. Although catheter angiography remains the diagnostic gold standard, and nuclear-medicine techniques best perform hemodynamic studies, less invasive imaging techniques have become efficient in serving these purposes. Conventional MRI and MR angiography, as well as MR functional and metabolic studies, are now widely used in each stage of disease management, from diagnosis to follow-up. CT scan and Doppler sonography may also help assess severity of disease and effects of treatment. The aim of this review is to clarify the utility, efficiency and latest developments of each imaging modality in management of Moya-Moya disease.

Posterior reversible encephalopathy syndrome (PRES) is a recently proposed cliniconeuroradiologic entity with several well-known causes, such as hypertensive encephalopathy, eclampsia, and the use of cytotoxic and immunosuppressive drugs, as well as some causes more recently described. PRES is characterized by neuroimaging findings of reversible vasogenic subcortical edema without infarction. The pathogenesis is incompletely understood. Two opposing hypotheses are commonly cited, but the issue is controversial: (1) the current more popular theory suggests that severe hypertension exceeds the limits of autoregulation, leading to breakthrough brain edema; (2) the earlier original theory suggests that hypertension leads to cerebral autoregulatory vasoconstriction, ischemia, and subsequent brain edema. The clinical syndrome of PRES typically involves headache, encephalopathy, visual symptoms, and seizures. The clinical presentation is often nonspecific, and therefore the diagnosis of PRES has come to increasingly rely on magnetic resonance imaging (MRI) abnormalities consistent with PRES with documented recovery clinically and on repeated neuroimaging. The diagnosis has important therapeutic and prognostic implications because the reversibility of the clinical and radiologic abnormalities is contingent on the prompt control of blood pressure and/or discontinuing the offending drug.

This project explores the economic aspects of digital-only journals using ithink Analyst, a modelling software package. Three models have been produced using simulations to test model sensitivities. This paper first describes some background to the models, the software and how it was used. Each model in turn is then described and finally, the paper outlines plans to further develop models of digital journal production and delivery.

The paper reviews three important pieces of research funded by Reuters over the period 1994-1996 that surveyed the understanding of, and use of information by managers. The research shows that whilst managers are well aware of the importance of information, they frequently do not feel in control of their use of it. In particular, they find that they are not given all the information they need but at the same time are overwhelmed by too much information. They recognize information is important, but do not know how to value it. They think their organization has information policies, but are rarely aware of what those policies are. They find that their personal and social life can be damaged by the problems of too much information. Finally, librarians and information managers seem not to be considered as a solution to these problems. The research shows that there is a clear market niche for information managers to exploit.

Atomistic computer simulation with embedded atom method (EAM) interatomic forces was used to study the structure of surface steps on the {111} unreconstructed surface in fcc metallic materials. The energetics and local atomic relaxation behavior of ledges parallel to the 〈110〉 direction were studied using a potential describing lattice properties of Au. The vacancy formation energies in the stepped surfaces was also studied, and it was found that the energy of formation of a vacancy in a terrace is the same as that in the perfect unstepped surface. This value is 30% lower than that of the bulk. The vacancy formation energy in the ledge is reduced by a factor of two with respect to that of the terraces. The structure of the “up ledge” (A step) is different from the “down ledge” (B step). These differences do not significantly affect the energy of the ledges, although they do affect the vacancy formation energies in sites in the second surface layer near the ledge. The implications of the results for the formation of kinks and the general structure of high index surfaces are discussed.

There are few large series of the long-term results of severe devascularized, open fractures to the lower extremity. Therefore, we retrospectively reviewed our experience with 35 consecutively admitted patients who sustained Gustilo Type IIIC injuries and who presented to our Reimplantation Center between 1984 and 1987. To our knowledge, this group of patients represents the largest series of this injury reported to date. The review included 21 patients who required primary amputation and 14 patients who underwent vascular, orthopedic, and delayed soft tissue reconstruction. This report details the treatment protocol used to result in our 93% success rate in the 14 patients with Type IIIC injuries who were successfully revascularized. Our initial management approach to the devascularized lower limb includes immediate revascularization with temporary shunts to minimize ischemia time, followed by revascularization with vein grafts beyond the zone of injury and external fixation. Subsequent management included liberal use of microsurgical free transplantation to overcome soft tissue defects ; bone grafting as soon as infection and soft tissue coverage permitted and delayed wound closure. Our approach differs in that definitive wound closure is avoided for 4 to 6 weeks to allow resolution of myonecrosis secondary to initial ischemia and subsequent reperfusion injury. Contraindications to this aggressive revascularization approach are poor patient health before injury, completely severed limb, segmental tibial loss greater than 8 cm, ischemia time greater than 6 hours, and severance of the posterior tibial nerve.

Introduction La telemedecine ameliore l’accessibilite aux soins urgents pour les patients victimes d’AVC. L’analyse de deploiements d’autres reseaux identifie 4 cles pour les reussir : la formation, l’analyse des prises en charge, l’ergonomie et les adaptations. La plateforme de telemedecine ORTIF se deploie depuis janvier 2015 en Ile de France. Elle impliquera a terme 100 etablissements pour des expertises en neurochirurgie, pour les AVC et la neurologie. Elle permet de partager sur le Web des donnees medicales, de l’imagerie et de realiser des visio-consultations. Elle accueille aussi des reseaux en medico-social et ambulatoire pour 30 structures. Le GCS D-SISIF en charge du cadrage du projet, du deploiement et accompagnement, a concu un processus d’industrialisation. Methode Des comites scientifiques et techniques ont defini les organisations, le teledossier, les aspects medico-economiques et des tableaux bord de suivi. Une hotline et un site de formation e-learning ont ete crees. Un point d’etape a ete realise en juillet 2015. Resultats Quarante-trois etablissements ont ete deployes. Cinq cent quinze acteurs ont beneficie d’une formation. La note de satisfaction etait de 3,4/4. Ont transite via la plateforme 1271 avis d’expertise : 1043 avis neurochirugicaux, 66 avis neurovasculaires et 162 avis de neuroradiologie. La progression de la creation de teledossier etait de 177 % entre les mois d’avril et mai au profit surtout de l’expertise neurochirurgicale qui beneficiait d’une experience de telemedecine prealable. Le faible nombre de centres experts neurovasculaires deployes initialement explique les usages moins nombreux mais montrent l’importance d’un accompagnement des acteurs dans ces nouvelles modalites d’expertise. La proportion de recours a la hotline (nombre d’incidents/nombre etablissements fonctionnels) etait de 2,4 en fin de premier mois du deploiement et de 0,78 dans le dernier mois objectivant la qualite fonctionnelle. Conclusion La telemedecine est un outil support aux organisations medicales pour permettre une amelioration de l’accessibilite aux soins et donc de leur qualite. L’accompagnement des acteurs est un enjeu fort de la reussite du deploiement de tels projets.

Online systems have been affecting the banking sector dramatically worldwide for the past 20 years. A summary of recent developments of online banking systems in China is provided. After a brief description of the previous three generations of online systems, the authors argue that the next generation online systems in banking lies in the intelligence network with full integration of management support, operating services, information services and customer services. This paper also summarizes dominant characteristics of the Chinese banking system and its recent online developments, and evaluates different online strategies practised by some major Chinese banks. The authors suggest that it is important for Chinese banks to consider four factors in their online strategy formation.

To the Editor: Haik et al. present a case report of a patient with histologically confirmed sporadic Creutzfeldt-Jakob disease (sCJD) with bilateral increased signal in the pulvinar of the thalamus.1 We felt it important to clarify recent changes in the definition of the pulvinar sign to avoid difficulties in future diagnosis of variant CJD (vCJD) using MRI. The presence of pulvinar hyperintensity was originally described as a characteristic feature of vCJD by Sellar et al.2 in 1997, and the high sensitivity and specificity of this sign were subsequently documented by our group.3 Clinical criteria for a diagnosis of vCJD were formulated that incorporated these MRI findings with diagnostic changes defined as bilateral pulvinar high signal on MRI scan.4 It has been recognized that this definition was ambiguous, …

This study aimed at determining brain structural imaging correlates of neurological soft signs (NSS) in patients suffering from a first-episode psychosis.Fifty-two patients with a DSMIV diagnosis of first-episode psychosis (schizophrenia or schizophrenia spectrum disorder) were consecutively included. Subjects were assessed using a standardized neurological examination for motor coordination, motor integration and sensory integration. Anatomical magnetic resonance images (MRI) were analysed in the whole brain using optimized voxel-based morphometry.Neurological soft signs (NSS) total score (P-corrected = 0.013) and motor integration subscore (P-corrected = 0.035) were found to negatively correlate with grey matter structure of the dorsolateral prefrontal cortices. Motor coordination subscore was positively correlated with grey matter structure of the thalami (P-corrected = 0.002) and negatively with white matter structure of the cerebellum (P-corrected = 0.034). The addition of age and gender as covariate yielded similar results. We did not find any correlation between neither sensory integration subscore and grey matter structure nor NSS total score, motor integration subscore and voxel-based morphometry (VBM) white matter structure.Structural alteration in the cerebello-thalamo-prefrontal network is associated with neurological soft signs in schizophrenia, a candidate network for 'cognitive dysmetria'.

The high-resolution waveguide terahertz (THz) time-domain spectra (20-100 cm(-1)) of the two structural isomers 1,2-dicyanobenzene (1,2-DCB) and 1,3-dicyanobenzene (1,3-DCB) have been modeled and assigned using solid-state density functional theory. The THz spectra of these similar molecules are distinctly different in the low-frequency region with the differences being driven by modifications of the crystal packing arrangement between the isomers. Simulations utilizing the hybrid density functionals B3LYP and PBE0 were performed to determine the origins of the observed vibrational features. External lattice vibrations (hindered translations and rotations) are found to dominate these spectra, reinforcing the need for proper solid-state models in the analysis of the THz spectra of organic molecular solids. These calculations were able to account for all of the observed spectral features exhibited by both isomers, even in the case of 1,2-DCB, where the spectrum was found to be the result of two coexisting crystalline polymorphs.

Imaging of water diffusion or diffusion-weighted MR imaging provides physiological information about brain diseases that cannot be obtained from conventional sequences. This technique is very sensitive for the detection of cerebral ischemia from arterial origin and can distinguish cerebral ischemia from other non-vascular brain pathologies in patients presenting with abrupt onset of focal neurological deficit. Diffusion-weighted imaging is used for the evaluation of non-vascular diseases as well. Combined with conventional sequences, it is helpful to differentiate brain abscesses from necrotic tumors. Quantitative diffusion-weighted imaging provides additional information in the characterization of tumors or inflammatory, degenerative and metabolic lesions. Finally, diffusion-weighted imaging data also has prognostic value.

We investigated the relationship between tumor blood-flow measurement based on perfusion-imaging by arterial spin-labeling (ASL) and histopathologic findings in adults' primitive glial tumours.Thus, 40 primitive brain tumors (8 low-grade and 32 high-grade gliomas according to the Sainte-Anne classification) were imaged using pulsed (n=19) or continuous (n=21) ASL. Relative cerebral blood flow (rCBF=tumoral blood flow/normal cerebral blood flow) between high- and low-grade gliomas were compared.Using pulsed ASL, differences in mean rCBF were observed in high- and low-grade gliomas although no significant (respectively 1.95 and 1.5). Using continuous ASL, mean rCBF were significantly higher for high-grade than for low-grade gliomas (P0.05). High-grade gliomas could be discriminated using a CBF threshold of 1.18, with a sensitivity of 88%, specificity of 60%, predictive positive value of 88%, and predictive negative value of 60%.ASL-based perfusion provides a quantitative, non-invasive alternative to dynamic susceptibility contrast perfusion MR methods for evaluating CBF. ASL is a suitable method for gliomas initial staging and could be useful to identify intermediate tumoral evolution.

To report clinical and imaging features of diffuse cerebral vasoconstriction and to discuss the role of non-invasive imaging modalities for the diagnosis and the follow-up.Retrospective study including 13 consecutive patients with a diffuse cerebral vasoconstriction. Evaluation of the sensitivity of Doppler US and magnetic resonance angiography for the diagnosis.The diagnosis is based on the association of a thunderclap headache, declenching factors found in 50% of cases and of stenosis involving middle and small cerebra arteries. In some cases cerebral hemorrhage may be present.Diffuse cerebral vasoconstriction is a rare cause of thunder clap headhache, which needs to exclude other causes such as subarchnoid hemorrhage from aneurysm rupture. Non contrast CT of the head, frequently normal, may be falsely reassuring. It is therefore necessary to further assess the cerebral arteries to exclude an aneurysm but also to detect the presence of stenoses that would suggest the diagnosis. Non-invasive imaging modalities (MRA and Doppler US) are favored for detection and follow-up of proximal lesions.

The ability of sodium taurocholate to increase the initial dissolution rate of five steroids was studied in terms of effects on solubility, wetting, and diffusion coefficient. For all compounds, wetting effects predominated over solubilization effects at bile salt concentrations representative of the fasted state. For hydrocortisone, triamcinolone, betamethasone, and dexamethasone, this trend also continued at the higher bile salt concentrations typical of the fed state. Bile salts solubilized these compounds by a factor of two or less, and diffusivity changes were negligible at bile salt concentrations up to 30 mM. For the more lipophilic danazol, the wetting effects were small and of importance only at premicellar levels of bile salt. At higher concentrations, the increase in solubility was the predominant factor. Incorporation into micelles appeared to decrease the diffusivity slightly, but this was important only at bile salts concentrations of 15 mM or higher. In conclusion, it appears that even within a series of structurally related compounds the mechanism by which bile salts mediate increases in dissolution rate can differ considerably.

Despite advances in diagnosis and treatment, atherosclerosis remains the second cause of death in the world. Due to technical advances, high resolution MRI (HR-MRI) allows depiction of the wall of cervical arteries, especially carotid atherosclerosis. HR-MRI allows visualization of the different components of atherosclerosis: necrotic lipid core, intraplaque hemorrhage, calcifications and fibrous cap. Global plaque volume as well as the volumes of individual plaque components can be calculated. Atherosclerotic plaque structure analysis, along with stenosis measurement, contribute to the stratification of the stroke risk. HR-MRI may also be used to assess treatment efficacy aimed at stabilizing or reducing plaque progression. Beyond the arterial lumen, direct evaluation of vessel wall should modify the management of atherosclerosis in the years to come.

To report the results of a radiological survey of the management of acute stroke prior to intravenous thrombolysis.A questionnaire on imaging as used in the management of stroke was sent to 80 stroke units across France at the beginning of 2007 and included the first imaging modality used (CT or MRI), the imaging protocol before treatment and the exclusion criteria followed for thrombolysis.CT was most often used as the first modality for the management of acute stroke (by 70% of the 53 responding centers) and 26 centers (49%) used both CT and MRI. Only 12 centers (22%) routinely performed MRI to screen for acute stroke. However, more than half the patients who had received thrombolysis in 2006 had been examined using MRI. In fact, after three-hour poststroke, intravenous thrombolysis was predominantly decided upon from MRI data. The survey showed that imaging criteria are well standardized for CT, whereas they are more variable for MRI. Furthermore, the majority (28 of 38) of the centers considered that thrombolysis could be applied despite a clinical contraindication (such as unknown time of onset or convulsions) if MRI categorically diagnosed an acute stroke.This survey showed that CT-based screening of acute stroke before thrombolysis remains the standard modality in France, with a consensus on decision-making criteria. The survey also revealed a change in imaging management, with a growing role for MRI as the first examination.

Magnetic resonance imaging (MRI) is the prominent imaging modality in the field of epilepsy. MRI plays a major role in describing and recognizing the malformations of cortical development and hippocampal sclerosis and has improved epilepsy patient care. MRI is also accurate in detecting the other major epilepsy etiologies (vascular malformations and cicatricial lesions). Presurgical MRI is relevant since it provides a high-resolution study of the brain.

Magnetic resonance imaging is an imaging technique allowing morphological and functional study of the brain. Algorithmic and technical advances offer new insights in such brain studies using new approaches to search epileptogenic lesion. Voxel based analysis appears as the dominant methodology to study grey and white matter using the following contrast: T1, T2, T2 relaxometry, magnetization transfert and diffusion weighted imaging. Ongoing development focuses on sulcal morphometry and gyrification index, to improve our understanding of developmental epilepsy. Magnetic resonance spectroscopy appears as a promising tool following availability of high field strength clinical MRI and evidence about its utility in the field of epileptology. Functional MRI benefits from such high field strength and new pulse sequence using diffusion gradients to probe neuronal firing.

Recent technical progress of MRI and CT made it possible to widen the field of exploration of the noninvasive vascular imaging in the study of supra-aortic, encephalic and medullary vessels. MRI of the carotid plaques, CT angiography in the detection of the intracranial aneurysms, intracranial time-resolved MRA and MRA of the spinal cord took their place in the field of the noninvasive vascular imaging.

Diffusion tensor imaging is a magnetic resonance imaging technique that provides details on tissue microstructure and organization well beyond the usual image resolution. With diffusion tensor imaging, diffusion anisotropy can be quantified and subtle white matter changes not normally seen on conventional MRI can be detected. The aim of this article is to review the principles of diffusion tensor imaging and fiber tracking and their applications to the study of the brain, including Alzheimer disease, neuropsychiatric disorders, strokes, multiple sclerosis, brain tumors, and intractable seizures. Emerging applications to spinal cord disorders are also presented.