Unruptured intracranial aneurysms: An updated review of current concepts for risk factors, detection and management.

The management of patients with unruptured intracranial aneurysms (UIAs) is a complex clinical challenge and constitutes an immense field of research. While a preponderant proportion of these aneurysms never rupture, the consequences of such an event are severe and represent an important healthcare problem. To date, however, the natural history of UIAs is not completely understood and there is no accurate means to discriminate the UIAs that will rupture from those that will not. Yet, a good understanding of the recent evidence and future perspectives is needed when advising a patient with IA to tailor any information to the given patient's level of risk and psychoaffective status. Thus, this review addresses the current concepts of epidemiology, risk factors, detection and management of UIAs.

Susceptibility vessel sign on T2* magnetic resonance imaging and recanalization results of mechanical thrombectomy with stent retrievers: a multicentre cohort study.

BACKGROUND AND PURPOSE: The susceptibility vessel sign (SVS) on T2*-weighted magnetic resonance imaging has been reported in several studies as a negative predictor of early recanalization after intravenous thrombolysis. The meaning of SVS regarding the results of mechanical thrombectomy with stent retrievers was investigated. METHODS: Susceptibility vessel sign presence and length were studied in 153 acute ischaemic stroke patients (82 men; mean ± SD age 59 ± 17 years, baseline National Institutes of Health Stroke Scale score 17.2 ± 6.5) from three stroke centres, treated with either mechanical thrombectomy alone (n = 84) or bridging therapy (n = 69). Variables were compared between recanalizers, defined as thrombolysis in cerebral infarction (TICI) scores ≥2b, and non-recanalizers (TICI<2b). RESULTS: The SVS was present in 113 (73.8%) patients. There was no association between the presence of SVS and recanalization, obtained in 86 (56.2%) patients, in the whole population [odds ratio (OR) 1.24, 95% confidence interval (CI) 0.53-2.92, P = 0.84) and in treatment subgroups (bridging: OR = 0.91, 95% CI 0.29-2.87, P = 1.0; thrombectomy alone: OR = 1.85, 95% CI 0.48-7.16, P = 0.54). However, in SVS+ patients, recanalization decreased with SVS length (OR 0.94 for each additional mm, 95% CI 0.89-0.99; P = 0.02). CONCLUSIONS: The success of recanalization in acute stroke patients treated with stent retrievers was related to thrombus length but not to the presence of SVS.

[Imaging Moya-Moya disease]. / Imagerie du Moya-Moya.

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.

Intrathecal antibody kinetics in neuroborreliosis: A report on three cases and a literature review.

Borreliosis is a common affliction in northern countries and its neurological manifestations often mislead trained clinicians. We present three cases of Lyme neuroborreliosis, with intrathecal synthesis of specific antibodies, lymphocytic meningitis and magnetic-resonance imaging (MRI) findings. Our description aims at illustrating the natural history of the infection, highlighting persistent intrathecal synthesis of anti-Borrelia antibodies months after treatment completion, and its clinical significance. We then review the literature on MRI findings in neuroborreliosis and the kinetics of intrathecal synthesis of specific anti-Borrelia antibodies.

Subarachnoid hemorrhage in ten questions.

Traumatic subarachnoid hemorrhage (SAH) has an annual incidence of 9 per 100 000 people. It is a rare but serious event, with an estimated mortality rate of 40% within the first 48hours. In 85% of cases, it is due to rupture of an intracranial aneurysm. In the early phase, during the first 24hours, cerebral CT, combined with intracranial CT angiography is recommended to make a positive diagnosis of SAH, to identify the cause and to investigate for an intracranial aneurysm. Cerebral MRI may be proposed if the patient's clinical condition allows it. FLAIR imaging is more sensitive than CT to demonstrate a subarachnoid hemorrhage and offers greater degrees of sensitivity for the diagnosis of restricted subarachnoid hemorrhage in cortical sulcus. A lumbar puncture should be performed if these investigations are normal while clinical suspicion is high.

Patient "candidate" for thrombolysis: MRI is essential.

Because of its excellent sensitivity and specificity to diagnose arterial ischemic stroke (AIS) in the acute phase, MRI answers the main questions to guide treatment in "candidates" for thrombolysis. It lasts less than ten minutes, can confirm the diagnosis of AIS and distinguish it from hematomas and other "stroke mimics". It can identify the ischemic penumbra (perfusion-diffusion mismatch), determine the site of occlusion and provide prognostic information to adapt treatment in some cases in which the indications are poorly defined. In light of the most recent scientific findings, MRI can guide the treatment turning it into the investigation of choice in "candidates" for thrombolysis.

Advanced technologies applied to physiopathological analysis of central nervous system aneurysms and vascular malformations.

While depiction and definition of morphological and architectural characteristics of CNS vascular disorders remains the first step of an MR analysis, emerging imaging techniques offer new functional information that might help to characterize rupture risk of CNS vascular disorders. Two main orientations are suggested by recent studies: inflammation of the vessel wall and analysis of physical constraints of blood flow using 4D flow imaging (shear parietal). This paper will focus on radiological application of 4D flow imaging and inflammation imaging, in the characterization of potential prognostic markers of CNS vascular disorders. We will review the basic technical considerations of 4D flow MRA, inflammation imaging and discuss their applications in CNS vascular disorders: aneurysms, arteriovenous malformation, dural arteriovenous fistulas. We will illustrate their potential in the development of individual rupture risk criteria in brain vascular disorders.

Imaging of cervical artery dissection.

Cervical artery dissection (CAD) may affect the internal carotid and/or the vertebral arteries. CAD is the leading cause of ischemic stroke in patients younger than 45 years. Specific treatment (aspirin or anticoagulants) can be implemented once the diagnosis of CAD has been confirmed. This diagnosis is based on detection of a mural haematoma on ultrasound or on MRI. The diagnosis can be suspected on contrast-enhanced MRA (magnetic resonance angiography) or CT angiography, in case of long stenosis, sparing the internal carotid bulb, or suspended, at the junction of V2 and V3 segments of the vertebral artery, in patients with no signs of atheroma of the cervical arteries. MRI is recommended as the first line imaging screening tool, including a fat suppressed T1 weighted sequence, acquired in the axial or oblique plane at 1.5T, or 3D at 3T. Complete resolution of the lumen abnormality occurred in 80% of cases, and CAD recurrence is rare, encountered in less than 5% of cases. Interventional neuroradiology (angioplasty and/or stenting of the dissected vessel) may be envisaged in rare cases of haemodynamic effects with recurring clinical infarctions in the short-term.

Non-invasive diagnosis of intracranial aneurysms.

Patients need to be examined for intracranial aneurysms if they have had a subarachnoid hemorrhage. The preferred technique in this situation is CT angiography. Screening can be done for familial forms or for elastic tissue disorders, for which the first line investigation is magnetic resonance angiography. These non-invasive methods have now taken over from conventional angiography that was reserved for the pretreatment phase. A good technical knowledge of these imaging methods, their artifacts and misleading images enables reliable detection of intracranial aneurysms and for an accurate report to be returned to clinicians.

Tips and traps in brain MRI: applications to vascular disorders.

The French Society of Radiology's guide to good use of medical imaging examinations recommends MRI as the first-line examination for exploring cerebrovascular events or disorders. This paper will discuss the main traps in the images when stroke is suspected and provide the technical tips or knowledge necessary for an optimal radiological report.