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Competing Interests: G. Boulouis, D. Trystram, F. Nataf, C. Rodriguez, B. Devaux, C. Oppenheim, J.-F. Meder et O. Naggara déclarent n’avoir aucun lien d’intérêts.

Competing Interests: G. Boulouis, D. Trystram, F. Nataf, C. Rodriguez, B. Devaux, C. Oppenheim, J.-F. Meder et O. Naggara déclarent n’avoir aucun lien d’intérêts.

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., (Copyright © 2014 Elsevier Masson SAS. All rights reserved.)

Purpose: 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., Patients and Methods: 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., Results: 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 (P<0.05). 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%., Conclusion: 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., (Copyright © 2011 Elsevier Masson SAS. All rights reserved.)

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.

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.

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.

Owing to its rapid acquisition time and high sensitivity, diffusion-weighted imaging has turned into a routine sequence for brain imaging. This is the case not only for stroke, but also for various diseases such as abscesses or tumors. Being aware of the artifacts is important for optimal interpretation. After a brief review of the normal patterns, the most frequent artifacts, inherent to the echoplanar imaging technique, are described and we provide suggestions to avoid them. Most current traps are caused by T2-weighting of the diffusion images; the key for avoiding erroneous interpretation relies on the ADC map.

Acute stroke patients represent an important diagnostic and therapeutic challenge. Patients with brain damage in the ischemic, but not yet infarcted, phase have the greatest potential for recovery. Here we review the most commonly employed diagnostic tools that are currently used before stroke therapy. While computed tomography is pertinent to differentiate ischemic from hemorrhagic stroke, this technique cannot be used as an etiological screening too. The ischemic origin of symptoms can be confirmed with magnetic resonance imaging which also contributes to for therapeutic decision making, prognosis assessment and etiological screening.

The advent of new imaging techniques, such as diffusion-weighted sequences, has a great impact on the diagnostic imaging in stroke. The aim of the present paper is to review the brain imaging patterns after stroke, highlight the usefulness of imaging technique for the diagnosis and etiological work-up after stroke. Three causes of ischemic stroke (cerebral venous thrombosis, aortic arch atheroma, patent foramen ovale) are detailed.

Intracranial metastases account for up to 35% of intracranial tumors in adult. They can involve any part of the central nervous system: brain, meninges and cranial nerves. Any systemic tumor can metastasize to the brain; the most common primaries include lung, breast and melanoma. Imaging plays a major role in the evaluation and management of patients with metastatic brain tumors. This article discusses optimal CT and MR imaging protocols and describes imaging features and distinguishing characteristics of cerebral and meningeal metastases.

Cerebral venous thrombosis is a rare and life threatening condition that should be considered in all individual with unusual and intractable headache. Young adults and children are typically affected and the superior sagittal sinus is most often concerned by thrombosis. MRI is the most sensitive examination technique and is now required for early diagnosis, leading to an improved prognosis. One or several prothrombotic risk factors are identified in most patients but about 20% of cerebral venous thrombosis have no cause identified. Anticoagulation is started as soon as the diagnosis is considered, even in the presence of hemorrhagic infarcts, and rapidly improves the condition in most patients. In situ thrombolysis is exceptionally delivered.

Purpose: To estimate the value of duplex color-coded ultrasonography in the initial diagnosis of acute cervical artery dissection., Material and Method: Retrospective study of 31 patients, mean age 45, sex ratio=1, referred for clinical suspicion of cervical artery dissection, confirmed by MRI. 46 dissected arteries were imaged. Ten patients presented multiple dissections. The evaluated sonographic diagnostic criteria were the direct signs of intra-mural hematoma: localized increased diameter of the artery, narrowed lumen, hypo and/or isoechoic intra-mural hematoma, intimal flap. The associated criteria studied were: the location of intra-mural hematoma and in case of an occlusion, the dissection of an other artery., Results: We analyzed separately the arterial segments visualized in B-mode ultrasound (supra-bulbar internal carotid artery, vertebral artery from V0 to V3) and the arterial segments evaluated only by pulsed Doppler (intrapetrosal carotid artery, V3-V4 of the vertebral artery). With the above criteria, on arterial segments visualized in B-mode ultrasound, the diagnosis of dissection was done in 83% of cases during the initial examination but in only 30% of the arterial segments non visualized on ultrasonography., Conclusion: The direct signs of intra-mural hematoma on internal carotid and vertebral segments imaged by B-mode ultrasonography have a good sensitivity. Because results were compared to MRI, the specificity could not be assessed. In case of occlusion of an artery, multiple dissections are a strong argument for the diagnosis.

Purpose: Diffusion-weighted imaging (3 directions) and diffusion tensor imaging (9 directions) were compared for their sensitivity to detect ischemic lesion., Materials and Methods: 41 patients (18 supposed transient ischemic attacks, 23 arterial stroke, MRI

Vascular diseases are an important part of orbital pathology. We describe vascular tumours of the orbit and vascular diseases with repercussion on the orbit, from intra or extra orbital origin. The classification of these abnormalities is difficult and several terms are used to describe the same histological entity. The objective of this work is, using the current classification, to illustrate the different imaging aspects of the most frequent vascular diseases of the orbit.

We report a case of a cavernous dural fistula in a 54-year-old man the source of inflammatory ocular symptoms. Poorly adapted treatment with corticosteroids led to iatrogenic complications. We will attempt to show the advantage of color Doppler imaging for the diagnosis of this infrequent lesion. The only indication of digitalized angiography is for endovascular treatment.

Over the last years, technical advances in neuroimaging have allowed drastic improvements in the assessment of acute ischemic cerebral events. Beyond conventional morphological analysis, diffusion-weighted and perfusion-weighted MRI now enable routine functional assessment of brain tissue; spectroscopy and diffusion tensor imaging still remains in the domain of clinical research. During acute ischemia events, diffusion-weighted MRI can detect the movements of water molecules and cytotoxic edema related to cell injury enabling rapid diagnosis and early assessment of cerebral ischemia. In conjunction with perfusion imaging, which detects hypoperfusion areas, diffusion-weighted MRI provides a means to identify areas of penumbra ischemia. More recent multislice computed tomographic (CT) scans with multimodal analysis are also very competitive for assessment of cerebral ischemia (non-enhanced CT, CT angiography and perfusion CT). The purpose of this paper is to describe the CT and MRI patterns during the different stages of cerebral infarcts.

The objective of brain imaging is to identify the hematoma according to its different stages and to find a potential underlying cause because of the risk of recurrence and the possibilities of treatment. In emergency, the diagnosis of hematoma is often obtained by CT scan, however today MRI has proved to be more accurate than CT to detect hemorrhage and to identify an underlying etiology. In some cases, according to the patient age, the medical history and the location of the hematoma, it may be necessary to perform a conventional angiography in order to exclude an intracranial vascular malformation. The aim of this review is to detail the different aspects of intracerebral hemorrhages according to the sequences and the temporal evolution, and to describe special findings which can help to identify an underlying etiology.

The advent of new MR techniques such as perfusion and diffusion weighted imaging has revolutionized diagnostic imaging in stroke. In some institutions, MRI is used as the sole screening imaging technique for acute stroke patients. In this document, the authors will review the MR pattern of acute ischemic arterial stroke, highlight the usefulness of MRI for the identification of acute hematomas and stroke like episodes, present the potential use of MRI in the management of acute stroke patients, especially when thrombolysis is contemplated, and discuss the role of MRI for imaging transient ischemic attack.

MRI has dramatically improved the management of cerebral tumors and consequently oligodendrogliomas. T1 and T2-weighted images and gadolinium enhancement are very useful for tumor detection and characterization. Tumor enhancement is of a great prognostic value because it is highly predictive of high-grade oligodendroglioma. Three-dimensional MR images provide, with high precision, the anatomical location and the relationships with functional structures (motor and language areas). The recent technical progress in MRI and the use of diffusion images in the screening of tumors lead to a better definition of the lesion. Comparative analysis of MRI images is helpful to detect eventual relapse and adverse effects of treatment.

Introduction: the objective of this study was to determine the role of radiological techniques in the diagnosis, assessment of severity and follow-up of cervical arterial dissections., Material and Methods: from 1995 to 2001 a multicentre retrospective study was conducted in 24 hospital centers. A multiple-choice questionnaire was sent to each center in order to collect clinical information and imaging details regarding the diagnosis and follow-up of cervical arterial dissections., Results: information was gathered on 459 patients, comprising a total of 384 carotid artery dissections and 170 vertebral artery dissections. A mean of 4.85 diagnostic examinations per patient were conducted. Morphological imaging of the brain by CT or by MRI was performed on all except 3 patients. Cervical Doppler ultrasound examination was the most frequently performed test throughout the entire study period (performed in 87% of patients). Conventional arteriography was a routinely employed test in 1995 whereas by 2001 it comprised only 31.2% of requested examinations, having been progressively replaced by MRI and MRA scanning, which comprised 60% of all examinations performed by 2001. A combination of cervical Doppler ultrasonography, axial MRI and MRA of the neck vessels were performed in 39.6% of patients in 2001. Examination of the intracranial vessels was performed by transcranial Doppler ultrasound in 40% of cases and by MRA in 30% of cases. For the follow-up of arterial dissections, an average of 1.4 examinations was performed per patient. The majority of such follow-up examinations comprised Doppler ultrasound and/or MRA of the neck arteries., Conclusion: The imaging diagnosis and follow-up of cervical arterial dissections will increasingly rely on non-invasive imaging techniques.

Several diseases may cause non-specific MR signal abnormalities of the bilateral basal ganglia and thalami. As such, diagnosis of the underlying etiology may be difficult to achieve at imaging. In this review, we will present interpretative guidelines based on clinical data (mode of presentation, previous history, clinical symptoms, and evolution) and imaging data (type of signal abnormalities, location of lesions, and associated abnormalities). The main categories of diseases causing MR signal abnormalities of the bilateral basal ganglia and thalami in adults are reviewed: toxic, metabolic, vascular, tumoral, infectious and inflammatory diseases.

Conventional catheter angiography (CCA) remains the gold standard for the evaluation of most intracranial vascular malformations. MRA techniques such as Time of Flight, Phase Contrast or 3D contrast-enhanced MRA, provide anatomic evaluation but without hemodynamic information. Recently developed, dynamic MRA is based on dynamic acquisition of images and image subtraction; these two principal characteristics produce images comparable to those obtained by CCA. The purpose of this review is to explain the principles, advantages and drawbacks of this technique in the evaluation of arteriovenous malformations, arteriovenous fistulas, aneurysms and venous thrombosis.

Imaging evaluation of cerebral arteriovenous malformations (AVM) requires selective visualization of the different compartments of the malformation in order to select the therapeutic management. Conventional angiography remains the reference to analyze intracranial vessel conspicuity but non-invasive methods constitute an excellent alternative. Among these techniques, CT angiography is rarely used because of the need to inject iodinated contrast material and because of irradiation. MR angiography provides useful information and can be performed using several techniques: time of flight with or without contrast material injection, phase contrast, three-dimensional (3D) gradient echo acquisition after contrast material injection and, more recently, MR digital subtraction angiography. The purpose of this review article is to summarize the different non-invasive techniques for vascular imaging and to analyze the usefulness of these techniques for the assessment of brain AVMs.

The diagnostic approach of dementia has clearly improved with the progress in medical imaging, notably magnetic resonance imaging. The conventional T1 and T2 sequences or morphological imaging have demonstrated their interest in the positive and differential diagnosis of dementia, together with the more precise description of normal ageing of the brain. The ANAES (French medicines agency) proposes systematic brain imaging, notably by magnetic resonance imaging (MRI) in their practical guidelines for the diagnosis of Alzheimer's disease (http://www.anaes.fr). THE INTEREST OF CERTAIN IMAGING TECHNIQUES: The therapeutic progress in treatment of dementia implies that the different affections be recognised as early as possible. With this in mind, the functional MRI is capable of describing the damage in cases when morphological imaging is not sufficiently specific. Recent studies have reported the interest of diffusion and perfusion imaging, activation MRI and proton spectroscopy. FROM A THERAPEUTIC POINT OF VIEW: The combination of morphological and functional approaches will provide a better definition of the groups at risk in order to target current treatments and those to come.

Headaches constitute one of the most frequent reason of consultation. Their causes are extremely varied. The first step consists in the analysis of the characteristics of the pain and the associated signs in order to distinguish primary and secondary headaches. Primary headaches, including migraines and tension-type headaches are the most frequent types and do not require imaging evaluation. Secondary headaches are related to an organic cause and require specific investigations. In case of suspected symptomatic or secondary headaches, brain imaging plays an important role in the etiologic work-up. The main purpose of imaging in an emergency setting is to diagnose a life-threatening disease.

Carotid artery stenting (CAS) is currently being investigated as an alternative treatment to carotid endarterectomy (CEA). Cerebral embolism is the most serious risk of CAS. Carotid artery stenting is still not reimbursed and unauthorised not authorised in routine in France (excepted in trials with ethical committee approval). CAS is now feasible, with a high technical success, which may improves with learning curve and with a better patient selection of the patients. A number of higher risk situations for CEA represents ideal indications for CAS, such as restenosis after CEA, stenosis due to prior neck radiation and radical neck surgery, and lesions in the distal internal carotid artery or involving high, retromandibular bifurcation.

Diffusion tensor MR imaging is a technique that provides details on tIssue microstructure and organization well beyond the usual image resolution. With diffusion tensor MR imaging, diffusion anisotropy can be quantified and subtle white matter changes not normally seen on conventional MRI can be detected. The purpose of this article is to review the current applications of diffusion tensor MR imaging for the study of the brain, including normal aging, Alzheimer's disease, neuropsychiatric disorders, strokes, multiple sclerosis, brain tumors and intractable seizures.

Asymptomatic stenosis of the internal carotid artery requires a non-invasive imaging work-up. The objectives include the quantification of the degree of stenosis, the analysis of the atherosclerotic plaque and the consequences of this stenosis on the brain tissue. Previous studies showed the reliability of MR angiography and spiral CT for the assessment of the arterial lumen. However, the consensus is based on the association of ultrasonography and MRA because of the non-invasive approach of these examinations that allow a complete evaluation of both the extracranial and the intracranial vessels. Recent advances in MRI will probably allow to simultaneously analyze the arterial wall in order to detect the plaques at risk and to optimize the therapeutic approach.

Traditional data and recent advances in the field of spinal cord ischemia are reviewed, with special attention to clinical and radiological features, as well as underlying etiology, outcome, and pathophysiology. Acute spinal cord ischemia includes arterial and venous infarction and global ischemia resulting from cardiac arrest or severe hypotension. MRI has become the technique of choice for the imaging diagnosis of spinal cord infarction. Correlation of clinical and MRI data has allowed diagnosis of clinical syndromes due to small infarcts in the central or peripheral arterial territory of the spinal cord. Diffusion-weighted MR imaging may increase the sensitivity and specificity for diagnosis of acute spinal cord infarction. Diagnosis of venous spinal cord infarction remains difficult. As for global ischemia, neuropathological studies demonstrated a great sensitivity of spinal cord to ischemia, with selective vulnerability of lumbosacral neurons. Chronic spinal cord ischemia results in a syndrome of progressive myelopathy. The cause is usually an arteriovenous malformation. Most often, diagnosis may be suspected on MRI, leading to diagnostic, and eventually therapeutic, spinal angiography.

Intracerebral hematoma is mainly due to the spontaneous rupture of small vessels damaged by chronic hypertension or amyloid angiopathy. In some cases, intracerebral hemorrhage may be associated with a vascular malformation, a tumor, venous thrombosis or hemorrhagic transformation of a cerebral infarct. The objective of brain imaging is to identify the hematoma according to its different stages and to find a potential underlying cause because of the risk of recurrence and the possibilities of treatment. In emergency, a diagnosis of hematoma may be obtained by CT scan or MRI but the etiologic work-up requires early MRI. According to the patient's age, the medical history and the location of the hematoma, it may be necessary to perform conventional angiography in order to exclude an intracranial vascular malformation. The aim of this review is to detail the different aspects of intracerebral hemorrhages and to discuss the main causes that can be found at brain imaging.

This article summarizes the role of imaging in the evaluation of cognitive disorders of the elderly. The primary goal of imaging is to exclude potentially reversible dementia due to intracranial lesions such as tumor, subdural hematoma or normal pressure hydrocephalus. The value of neuroimaging in the diagnosis of degenerative disorders is then discussed: Alzheimer's disease, frontotemporal dementias, dementia with Lewy bodies, dementia associated with parkinsonian syndromes, vascular dementias and mild cognitive impairment.

Multiple imaging techniques are available to diagnose cervical arterial dissections. It may be possible to image the vessel wall hematoma (US, MRI, 2D or 3D MRA source images, CTA source images), the narrowed arterial lumen (MRA, CTA, catheter angiography), or the hemodynamic impact of the affected vessel. There is no available guideline in the literature regarding the imaging work-up at diagnosis or follow-up. The Société Française Neurovasculaire and the Société Française de Neuroradiologie have sponsored a multi-center study to evaluate current imaging strategies. Results from several centers, while being variable, do share some similarities: the preferred use of non-invasive or minimally invasive techniques to evaluate the vessel wall and the vascular lumen and/or hemodynamic impact, the use of fat suppressed sequences at MRI, the use of Gadolinium enhanced MRA, the limited interest for CT techniques, and the still important use of catheter angiography in selected cases.

IN ARTERIAL ISCHEMIC PATHOLOGY: Magnetic resonance imaging is increasingly proposed for any suspicion of cerebral vascular accident. Because of its diffusion sequences, it permits the rapid diagnosis and screening of ischemic lesions and provides prognostic information. FOR OTHER CEREBRAL VASCULAR DISORDERS: Intra-parenchymatous and sub-arachnoid hemorrhages are easily revealed by MRI. Today, MRI is the most effective examination for the diagnosis of venous thrombosis and of its impact on the parenchyma.

CRANIO-ENCEPHALIC TRAUMAS: Scanography remains the examination of choice. However, MRI can be useful in diagnosis of diffuse axional lesions, not clearly visualized with scanography, and for screening the subsequent lesions. INFECTIOUS OR INFLAMMATORY LESIONS: Some are very evocative with MRI: cerebral abscesses, notably herpetic encephalitis and Creutzfeldt-Jacob's disease. If multiple sclerosis is suspected, MRI is considered as the principle para-clinical examination able to confirm the diagnosis with the first episode. It also supplies data for the diagnosis of metabolic, toxic and degenerative diseases.

THE TECHNIQUE: Today, magnetic resonance imaging (MRI) is the exploration of choice for a number of central nervous system disorders. This technique, which does not use ionising rays, examines the encephalus in all its dimensions. Various sequences are used to study the cerebral parenchyma: specific sequences in T1, with or without injection of a contrast product, specific sequence in T2, and FLAIR sequence. THE RESULTS OBTAINED: The diffusion and perfusion imaging respectively reveal the movement of the water molecules and the cerebral microcirculation. Visualisation of the arteries and veins is non-invasive with magnetic resonance angiographical techniques. Study of the chemical composition of tissues (magnetic resonance spectroscopy) and of cerebral activation (functional activation imaging) will not be addressed.