Abstract: In this paper, the method for the creation of an anatomically and mechanically realistic brain phantom from polyvinyl alcohol cryogel (PVA-C) is proposed for validation of image processing methods such as segmentation, reconstruction, registration, and denoising. PVA-C is material widely used in medical imaging phantoms because of its mechanical similarities to soft tissues.
Abstract: BACKGROUND AND PURPOSE:Our aim was to compare 3D TOF-MRA sequences at 3T and 1.5T in the follow-up of coiled aneurysms. The follow-up of coiled intracranial aneurysms is mandatory to depict potential recanalization. 3D-TOF MRA is an appropriate tool for this purpose.MATERIALS AND METHODS:DSA and 3D TOF-MRA at 1.5T and 3T were performed in a prospective series of 126 aneurysms in 96 patients (58 women, 38 men; age, 25-75 years; mean, 51.3 + 11.3 years). DSA was the reference standard to which the accuracy of 3D TOF-MRA was compared. The quality of aneurysm occlusion was assessed independently and anonymously by a core lab by using a 3-grade scale (total occlusion, neck remnant, and aneurysm remnant). Adequate occlusion was defined as total occlusion or neck remnant and used in a 2-grade scale: adequate occlusion/aneurysm remnant.RESULTS:With DSA, total occlusion was depicted in 58 aneurysms (46.0%); neck remnant, in 33 aneurysms (26.2%); and aneurysm remnant, in 35 aneurysms (27.8%). Adequate occlusion was seen in 91 cases (72.2%). A remnant (aneurysm or neck) was depicted in 68 cases (54.0%). For the 3 imaging techniques and regardless of scale used, the interobserver agreement was always greater at 3T than at 1.5T. SE and NPV for the prediction of aneurysm remnant versus adequate occlusion were higher at 3T than at 1.5T (SE 3T, 0.74; SE 1.5T, 0.54; NPV 3T, 0.90; NPV 1.5T, 0.85).CONCLUSIONS:In this large prospective series of patients, 3D TOF-MRA was superior at 3T to 1.5T for the evaluation of coiled intracranial aneurysms.
Abstract: To compare 12-channel and 32-channel phased-array coils and to determine the optimal parallel imaging (PI) technique and factor for brain perfusion imaging using Pulsed Arterial Spin labeling (PASL) at 3 Tesla (T).
Abstract: OBJECTIVES: To compare 3D-TOF magnetic resonance angiography (MRA) and contrast-enhanced MRA (CE-MRA) sequences at 3T in the follow-up of coiled aneurysms with digital subtracted angiography (DSA) as the gold standard. METHODS: DSA, 3D-TOF and CE-MRA were performed in a prospective series of 126 aneurysms in 96 patients (57 female, 39 male; age: 25-75 years, mean: 51.3 ± 11.3 years). The quality of aneurysm occlusion was assessed independently and anonymously by a core laboratory. RESULTS: Using DSA (gold standard technique), total occlusion was depicted in 57 aneurysms (45.2%), neck remnant in 34 aneurysms (27.0%) and aneurysm remnant in 35 aneurysms (27.8%). Sensitivity, specificity, positive predictive value and negative predictive value were very similar with 3D-TOF and CE-MRA. Visibility of coils was much better with 3D-TOF (95.2%) than with CE-MRA (23.0%) (P < 0.001). Also, substantial artefacts were less frequent with 3D-TOF (4.0%) than with CE-MRA (11.9%; P = 0.012). CONCLUSIONS: In this large prospective series of patients with coiled aneurysms, at 3T 3D-TOF MRA was equivalent to CE-MRA for the evaluation of aneurysm occlusion, but coil visibility was superior at 3D-TOF. Thus the use of 3D-TOF at 3T is recommended for the follow-up of coiled intracranial aneurysms. KEY POINTS: • Different Magnetic Resonance (MR) imaging techniques are used to evaluate intracranial aneurysms. • At 3T MR, 3D-TOF and CE-MRA appear equivalent for evaluating coiled aneurysms.. • Coils are better visualised on 3D-TOF than on CE-MRA. • Combined analysis of 3D-TOF and CE-MRA does not seem helpful. • At 3T, 3D-TOF techniques are recommended for monitoring patients with coiled aneurysms.
Abstract: To evaluate the agreement and diagnostic accuracy of Contrast enhanced magnetic resonance angiography (CE-MRA), Doppler ultrasound (DUS) and Digital subtraction angiography (DSA) in the assessment of carotid stenosis.
Abstract: Functional arterial spin labeling (fASL) is an innovative biomarker of neuronal activation that allows direct and absolute quantification of activation-related CBF and is less sensitive to venous contamination than BOLD fMRI. This study evaluated fASL for motor activation mapping in comparison with BOLD fMRI in terms of involved anatomical area localization, intra-individual reproducibility of location, quantification of neuronal activation, and spatial accuracy. Imaging was performed at 3T with a 32-channel coil and dedicated post-processing tools were used. Twelve healthy right-handed subjects underwent fASL and BOLD fMRI while performing a right hand motor activation task. Three sessions were performed 7days apart in similar physiological conditions. Our results showed an activation in the left primary hand motor area for all 36 sessions in both fASL and BOLD fMRI. The individual functional maps for fASL demonstrated activation in ipsilateral secondary motor areas more often than the BOLD fMRI maps. This finding was corroborated by the group maps. In terms of activation location, fASL reproducibility was comparable to BOLD fMRI, with a distance between activated volumes of 2.1mm and an overlap ratio for activated volumes of 0.76, over the 3 sessions. In terms of activation quantification, fASL reproducibility was higher, although not significantly, with a CVintra of 11.6% and an ICC value of 0.75. Functional ASL detected smaller activation volumes than BOLD fMRI but the areas had a high degree of co-localization. In terms of spatial accuracy in detecting activation in the hand motor area, fASL had a higher specificity (43.5%) and a higher positive predictive value (69.8%) than BOLD fMRI while maintaining high sensitivity (90.7%). The high intra-individual reproducibility and spatial accuracy of fASL revealed in the present study will subsequently be applied to pathological subjects.
Abstract: The standard technique for brain activation functional MRI (fMRI) is the BOLD sequence. Two new techniques have emerged: arterial spin labeling (ASL) MRI and diffusion MRI. Both have the theoretical advantage of more accurately directly demonstrating neuronal activation compared to BOLD imaging, resulting in improved spatial and temporal resolution. ASL is a perfusion sequence using labeled arterial protons as an endogenous perfusion agent. In spite of methodological difficulties, quantitative CBF measurements are possible. ASL is less susceptible to venous contamination than BOLD and more reproducible. Diffusion MRI evaluates neuronal activation at the cellular level with the prospect of excellent spatial resolution. The main limitations for both techniques are the technical difficulties in the acquisition and the low SNR. AS such, ASL is not widely used clinically and diffusion remains in the field of research. However, the increasing availability of 3T MR systems coupled with multi-channel surface coils and improved postprocessing techniques should improve the detection of the brain activation signal. It is thus possible that these techniques could become clinically available either in complement to or as a replacement for BOLD imaging.
Abstract: To describe an optimized 3D time-resolved contrast-enhanced MR angiography (3D TR-CE-MRA) at 3T in diagnosing head and neck paragangliomas and assessing their morphology and relation to neighboring vessels.
Abstract: No practical tool has been reported in the literature to evaluate the quality of cerebral TR-3D-CE-MRA techniques. Our study assessed a large list of parameters used to propose a quality-evaluation scheme for TR-3D-CE-MRA.
Abstract: Imaging of the cerebral arterial circle (CAC) is essential in neurovascular diseases such as ischemic stroke for detecting arterial occlusions and evaluating arterial supply, and in subarachnoid or intralobar hemorrhage for detecting intracranial malformations. Multidetector computed tomography angiography (MD-CTA) is increasingly being used for the detection and treatment planning of intracranial aneurysm. For optimal interpretation and treatment planning, this method requires suitable post-processing equipment, and extensive knowledge of the relevant anatomy and anatomical variants. Anatomical variants of the CAC are common, particularly in the anterior CAC, the most common site of intracranial aneurysm. The aim of this review is to illustrate the normal anatomy and most common anatomical variants of the anterior CAC detected by MD-CTA, and to discuss the relevant embryological and technical considerations.
Abstract: We propose a method for the creation of an anatomically and mechanically realistic brain phantom from polyvinyl alcohol cryogel (PVA-C) for validation of image processing methods for segmentation, reconstruction, registration, and denoising. PVA-C is material widely used in medical imaging phantoms for its mechanical similarities to soft tissues. The phantom was cast in a mold designed using the left hemiphere of the Colin27 brain dataset and contains deep sulci, a complete insular region, and an anatomically accurate left ventricle. Marker spheres and inflatable catheters were also implanted to enable good registration and simulate tissue deformation, respectively. The phantom was designed for triple modality imaging, giving good contrast images in computed tomography, ultrasound, and magnetic resonance imaging. Multimodal data acquired from this phantom are made freely available to the image processing community (http://pvabrain. inria.fr) and will aid in the validation and further development of medical image processing techniques.
Abstract: The aim of the present study was to compare patients displaying chronic and treatment-resistant depression with healthy controls, using the resting-state perfusion with arterial spin labeling (ASL) perfusion magnetic resonance imaging (MRI) technique at 3T. The study focused on the subgenual anterior cingulate cortex (sACC), which is a key component in the pathophysiology of depression. Six patients with chronic and treatment-resistant depression and six healthy control subjects were included. ASL is an innovative imaging technique which sidesteps the limitations of other functional neuroimaging techniques (functional MRI, positron emission tomography). A statistical analysis of perfusion maps was performed using SPM2 software. Statistically significant hyperperfusion regions were found in the depressed patient group compared with the healthy control group in the following: the bilateral sACC, left prefrontal dorsomedian cortex, left ACC and left subcortical areas (putamen, pallidum and amygdala). This study confirmed the involvement of the sACC in depression, particularly chronic and treatment-resistant depression, using ASL at 3T, a safe perfusion technique that seems to be appropriate for investigating functional abnormalities in psychiatric disorders.
Abstract: To compare 3D time-of-flight MR angiography (TOF-MRA) at 3 Tesla (3T) with digital subtraction angiography (DSA) for the evaluation of intracranial aneurysm occlusion after endovascular coiling.
Abstract: Even if acute subarachnoid hemorrhage (SAH) accounts for only 5% of strokes, its diagnosis is very important because its clinical consequences can be tragic. Recent technological advances in medical imaging have improved diagnostic and therapeutic management of patients with SAH. Nonenhanced CT of the head is the initial imaging modality in suspected SAH for the detection of ruptured intracranial aneurysms. Digital subtraction angiography (DSA) remains the reference exam. Multidetector row CT angiography may potentially replace DSA in the emergency setting, as it provides image data that allows evaluating aneurysmal morphology, the neck size or the visualization of vessels in the vicinity of the aneurysm. For SAH unrelated to aneurysm rupture (15% of cases), MRI and MRA can be added to the diagnostic work-up in order to exclude other differential diagnoses such as venous thrombosis or angiitis. Finally, transcranial color-coded duplex sonography, CT, or MRI are used in clinical practice in order to detect aggravating factors of SAH like hydrocephalus or vasospasm.
Abstract: The purpose of this study was to determine whether coil embolisation with a new complex-shaped Guglielmi Detachable Coil (GDC 360 degrees; Boston Scientific Neurovascular, Fremont, CA, USA) has any effect on the stability of aneurysm occlusion.
Abstract: To evaluate the effectiveness of three-dimensional (3D) dynamic time-resolved contrast-enhanced MRA (TR-CE-MRA) using a combination of a parallel imaging technique (ASSET: array spatial sensitivity encoding technique) and a time-resolved method (TRICKS: time-resolved imaging of contrast kinetics) and to compare it with 3D dynamic TR-CE-MRA using ASSET alone in the assessment of intracranial arteriovenous malformations (AVMs).
Abstract: The neuroradiologic location of asymptomatic paraclinoid aneurysms is decisive for patient management. In a preliminary study, we designed a paraclinoid MR protocol (PMP) including high-resolution T2-weighted images in 2 orthogonal planes to define the inferior limit of the distal dural ring plane that represents the borderline between the intradural and extradural internal carotid artery. In this clinical study, we compared this protocol with digital subtraction angiography (DSA) for the location of paraclinoid aneurysms. Materials and
Abstract: The aim of this study was to assess the long-term results of intracranial aneurysms treated with Guglielmi detachable coils (GDCs) with the aid of contrast-enhanced magnetic resonance (MR) angiography.
Abstract: To prospectively compare the agreement between digital subtraction angiography (DSA) and time-resolved magnetic resonance (MR) angiography with sensitivity encoding (SENSE) in combination with keyhole acquisition and contrast material-enhanced robust-timing angiography (CENTRA) k-space sampling techniques for the characterization of intracranial arteriovenous malformations (AVMs).
Abstract: Fluid-attenuated inversion recovery (FLAIR) sequences may reveal hyperintense vessel signals (HVS) at the acute stage of cerebral ischemia. The aim of this study was to test the hypothesis that HVS are associated with a worse outcome.
Abstract: The aim of this study was to develop an algorithm for the integration of time-resolved contrast-enhanced magnetic resonance (MR) angiography into dosimetry planning for Gamma Knife surgery (GKS) of arteriovenous malformations (AVMs) in the brain.
Abstract: Although MRI is increasingly proposed to investigate composition of carotid atherosclerosis, its reproducibility has rarely been addressed. We assessed the reproducibility of MRI for the identification and quantification of carotid atherosclerotic plaque components.
Abstract: The Guglielmi detachable coil (GDC) 360 degrees, a new complex shaped bare platinum coil, became available in Europe for aneurysm treatment in September 2005. The purpose of this study was to assess the feasibility and safety of selective embolization of intracranial aneurysms with the GDC 360 degrees in 52 consecutive patients.
Abstract: Time-resolved (TR) MR angiography (MRA) using parallel imaging techniques is proving to have clinical utility for improving MRA spatial and temporal resolution and separating arterial from venous anatomy. The purpose of this study was to evaluate TR MRA of the intracranial vessels at different integrated parallel acquisition technique (IPAT) factors.
Abstract: We assessed the value of three-dimensional (3D) dynamic magnetic resonance angiography (MRA) for the follow-up of patients with radiosurgically treated cerebral arteriovenous malformations (AVMs). Fifty-four patients with cerebral AVMs treated by radiosurgery (RS) were monitored using conventional catheter angiography (CCA) and 3D dynamic MRA with sensitivity encoding based on the parallel imaging. Cerebral AVM was qualitatively classified by two radiologists into one of five categories in terms of residual nidus size and persistence of early draining vein (I, >6 cm; II, 3-6 cm; III, <3 cm; IV, isolated early draining vein; V, complete obliteration). 3D MRA findings showed a good agreement with CCA in 40 cases (kappa=0.62). Of 23 nidus detected on CCA, 3D dynamic MRA showed 14 residual nidus. Of 28 occluded nidus on 3D dynamic MRA, 22 nidus were occluded on CCA. The sensitivity and specificity of 3D dynamic MRA for the detection of residual AVM were 81% and 100%. 3D dynamic MRA after RS may therefore be useful in association with MRI and can be repeated as long as opacification of the nidus or early venous drainage persists, one CCA remaining indispensable to affirm the complete occlusion at the end of follow-up.
Abstract: Diffusion-weighted magnetic resonance (MR) imaging (DWI), and three-dimensional (3D) time-of-flight (TOF) MR angiography (MRA), are highly sensitive for the early detection of stroke and arterial occlusion. However, only a few studies have evaluated the sensitivity of conventional MR sequences that are usually included in the imaging protocol. The aim of this study was to evaluate interobserver and intertechnique reproducibility of Fluid-Attenuated Inversion Recovery (FLAIR) sequences for the diagnosis of early brain ischemia and arterial occlusion.
Abstract: To compare the utility of contrast-enhanced MR Angiography (CE-MRA) with digital subtraction angiography (DSA) after endovascular treatment of intracranial aneurysms with Guglielmi detachable coils.
Abstract: The anatomy of the supratentoriel midline structures of the brain is complex: corpus callosum, third ventricle, trigone, choroid plexus, pineal gland, falx cerebri. Different types of tumors can arise from these structures including tumors of the trigone and septum, tumors of the falx, third ventricular tumors and pinal region tumors. These tumors share similar features: minimal clinical symptoms despite their occasional large size, mild non-specific intracranial hypertension syndrome, value of MRI for depiction of tumor location, stereotactic biopsy, relative difficulty of surgical management.
Abstract: During the latest years, numerous methods of multimodal image matching have been developed. Associated with medical imaging, these developments make it possible to match images using intrinsic data, as anatomical data, instead of external referential, as stereotactic frames. Thus, the use of intrinsic registration considerably increases possibilities in medical image analysis. Unfortunately, these techniques mostly remain in the research field and are rarely used in clinical daily practice. In this paper, we present a method for matching projective imaging (2D, radiography, angiography...) and tomographic imaging (3D, Magnetic Resonance Imaging, Computed Tomography). Furthermore, we propose a radiosurgical application for Arteriovenous Malformation (AVM). Radiosurgery planning for the treatment of AVM requires multiple image acquisitions in multimodality to define the irradiation target and to compute the dosimetry. All the planning images are acquired with a stereotactic frame. We describe in this paper the image registration technique that we propose to include diagnostic images in the planning process and the different steps required to validate our approach. In the current state, the results obtained do not enable us to replace the conventional technique due to the accuracy expected, but the analysis of the results shows that improvements of the protocol would make this application finally operational.
Abstract: Cervical artery dissection is an important cause of ischemic stroke, particularly in young patients. The diagnosis can be made with invasive catheter angiography or non-invasive imaging, either with MRI in conjunction with MR angiography (MRA) or CT angiography (CTA). Both modalities have been shown to have a high specificity and sensitivity. New developments such as multi-slice CTA (MSCTA) are emerging as an alternative methods for imaging the cervical and intracranial arteries. However, the contribution of modern MSCTA to carotid artery dissection has not been reported.
Abstract: 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.
Abstract: This study was undertaken to assess the utility of contrast-enhanced MR angiography at 6 months after endovascular treatment of intracranial aneurysms with Guglielmi detachable coils.
Abstract: Cerebral venous thrombosis (CVT) can be difficult to diagnose because of its wide spectrum of clinical manifestations. Its diagnosis may be further complicated when patients initially present with acute subarachnoid hemorrhage (SAH). We report on four patients with SAH revealing a CVT and discuss the role of imaging for diagnostic and pretherapeutic workup. In three women and one man presenting with severe headaches, images initially suggested SAH with no associated parenchymal bleeding. In all patients, SAH involved the sulci of the convexity and spared the basal cisterns. Digital subtracted angiography showed occlusion of intracranial venous sinuses but did not reveal any other cause of SAH. All patients improved with anticoagulant therapy. Risk factors for CVT and SAH, namely, head trauma and oral contraception, were identified in two patients. These cases highlight the fact SAH may reveal a CVT, which should be considered in the diagnostic workup of SAH, especially when the basal cisterns are not involved.
Abstract: We compared two methods of 3D digital subtraction angiography (DSA)--propeller and standard rotation--for the assessment of aneurysmal morphology and its relation to neighboring vessels. Aneurysms were correctly visualized and localized with both techniques. 3D DSA with propeller rotation technique seems to be effective and allows us to reduce the amount of contrast material related to a shortened acquisition time. Technical progress including propeller rotation allows a larger range of rotation and faster rotational speeds.
Abstract: Lateral, homonymous upper and lower field blind sectors sparing a horizontal zone define quadruple sectoranopia. This rare campimetric deficit involves ischemia or infarction of parts of the lateral geniculate body supplied by the distal anterior choroidal artery.
Abstract: A new, coated bioactive coil has been developed to improve the long-term results of endovascular treatment of intracranial aneurysms. The purpose of this preliminary study was to assess the feasibility and safety of selective embolization of intracranial aneurysms with Matrix coils in 20 consecutive patients.
Abstract: Multiple sclerosis (MS) with clinical onset after 50 years of age is unusual (between 1 and 6%) and is frequently misdiagnosed. Furthermore, brain magnetic resonance imaging (MRI) abnormalities are frequently observed in subjects over 50 years of age. The aim of this study was to describe brain MRI in late-onset MS to evaluate the sensitivity and specificity of radiological MS criteria in patients aged over 50 years. We evaluated the brain MRI of 20 patients with onset of MS after 50 years of age. We compared these MRI with 26 controls matched for age, sex and vascular risk factors. MRI were blindly analysed by two neuroradiologists according to Paty et al.'s [Neurology38 (1988) 180] criteria, Fazekas et al.'s [Neurology38 (1988) 1822] criteria and Barkhof et al.'s [Brain120 (1997) 2059] criteria. The mean age at MRI scanning was 58 years. Sensitivity was 90% for Paty et al.'s criteria, 80% for Fazekas et al.'s criteria and 85% for Barkhof et al.'s criteria. Specificity was 54% for Paty et al.'s criteria, 69% for Fazekas et al.'s criteria and 65% for Barkhof et al.'s criteria. Barkhof et al.'s criteria are less specific in older patients than in young patients. We suggest that spinal cord MRI and cerebrospinal fluid analysis should be systematically performed in suspected late-onset MS in order to increase the specificity of the diagnosis.
Abstract: 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.
Abstract: Endovascular treatment of intracranial aneurysms is too often associated with aneurysm recurrence due to coil compaction. High packing of coils prevents compaction. To increase the packing attenuation, we sought to evaluate the results of selective embolization of aneurysms with complex-shaped coils alone.
Abstract: The prognosis of cervical artery dissection (CAD) patients mainly depends on the severity of the initial stroke and the risk of subsequent stroke. The overall functional prognosis of patients with stroke due to CAD does not differ from that of young patients with stroke due to other causes. The annual risk of recurrent stroke ranges from 0.3 to 3.4%. Early recurrences are often in the territory of the CAD when arterial lesions had not completely recovered. Conversely, long-term recurrent ischemic events seem to take place in all territories and can be due to various mechanisms. The prognosis of CAD patients also depends on the arterial outcome. Stenotic lesions resolve within a few months, most often without visible sequel on angiogram, in about 70% of patients. Recanalization of occluded vessels is less frequent but in more recent studies, which used imaging to confirm the presence of a mural hematoma, recanalization occurred in up to 90% of cases. Carotid aneurysms persist in about two third of cases while vertebral aneurysms seem to frequently resolve. Complications related to persistent aneurysm seem to be exceptional. The overall risk of CAD recurrence is low, ranging from 0.3 to 1.4% but seems to be higher within the first month and some recurrences are asymptomatic. Patients with connective tissue disease or familial history of CAD have an increased risk of CAD recurrence, but other risk factors remain unknown.
Abstract: 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.
Abstract: Our aim was to develop 3D dynamic MR digital subtraction angiography with high temporal resolution without sacrificing spatial resolution by using sensitivity encoding for the evaluation of cerebral arteriovenous malformations.
Abstract: The causes of ischaemic brain damage are numerous. Four main groups are described: atherosclerotic disease of the cervical and intracranial arteries represents 50% of the causes, small vessel disease with lacunar infarcts 25%, cardio-embolic disease 20% and non-atheromatous arterial disease and blood dyscrasias 10%. In 10% of cases, no etiology is identified. MRI has a dominating place in the etiologic assessment of cerebral infarction, by distinguishing the various types of infarction, detecting associated abnormalities like leukoencephalopathy and haemorrhage and by analyzing the lumen and wall of vessels.
Abstract: 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.
Abstract: Endovascular detachable coil is being increasingly used for the treatment of cerebral aneurysms but little information is available about its feasibility and effectiveness in people. We assessed clinical outcomes in elderly patients with ruptured intracranial aneurysms treated with selective embolization.
Abstract: 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.
Abstract: To replace digital subtraction angiography (DSA) in carotid stenosis evaluation, noninvasive imaging techniques have to reach a high concordance rate. Our purpose is to compare the concordance rates of contrast-enhanced MR angiography (CEMRA) and CT angiography (CTA) with Doppler ultrasound (DUS) in clinical routine practice.
Abstract: Carotid angioplasty and stenting (CAS) is sometimes used as an alternative to surgery, despite the lack of evidence for its safety and efficacy.
Abstract: We report clinical and angiographic findings in eight patients treated by the endovascular approach for an intracranial aneurysm remnant after incomplete surgical clipping. They were seven women and one man, mean age 38 years (range 14-50 years). In three, the remnant was responsible for a recurrent subarachnoid haemorrhage. All were treated by embolisation of the remnant using Guglielmi detachable coils. In two, a nondetachable balloon was inflated in front of the remnant during coil detachment because of a wide neck. Mean clinical and imaging follow-up was 19 months (range 12-24 months). Immediate angiography showed complete occlusion of the remnant and follow-up clinical examination showed good or excellent recovery in all patients. Imaging follow-up confirmed persistent occlusion of the remnant in all cases.
Abstract: Carotid angioplasty and stenting, a so far non-validated procedure, may be an alternative to surgery in patients with a high surgical risk. However, it carries also a risk of cerebral embolic events. The purpose of this study was to evaluate tissue signal abnormalities in the brain before and after carotid angioplasty and stenting by means of diffusion- (DWI) and perfusion (PWI) weighted magnetic resonance imaging (MRI).
Abstract: To report long-term imaging follow-up and clinical outcome of 13 patients with a giant vertebrobasilar aneurysm treated by parent artery occlusion (PAO).
Abstract: 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.
Abstract: 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.
Abstract: A new, very compliant remodeling balloon microcatheter has been developed for the treatment of difficult wide-neck intracranial aneurysms (eg, arterial bifurcation or small artery aneurysms). We report selective embolization by the use of the remodeling technique with the HyperForm balloon in 16 consecutive patients with a wide-neck intracranial aneurysm located on an arterial bifurcation or a small artery or both.
Abstract: Endovascular treatment with detachable coils is an accepted alternative to surgical clip placement for intracranial aneurysms. The purpose of this study was to evaluate the safety and reliability of the Sapphire coil, a new platinum coil for the treatment of intracranial aneurysms.
Abstract: MRI is the examination of choice for the evaluation of ischemic brain injury. At the acute phase, this examination may differentiate infarcted tissue from hypoperfused tissue. At the subacute phase, MRI allows to confirm the diagnosis of ischemia, exclude other diagnoses, recognize the rare appearances of cerebral ischemia, distinguish the different aspects of infarct and detect some rare diseases at the origin of the ischemic event.
Abstract: An early diagnosis and heparin therapy have contributed to a decreased mortality in cerebral venous thrombosis (CVT). However, predictors of outcome are difficult to identify, because most studies suffered heterogeneity in diagnostic findings and treatments, retrospective design, and recruitment bias. The aim of this study was to evaluate the clinical outcome in 55 consecutive patients with CVT admitted over a 4-year period. The study population consisted of 42 women and 13 men, with a median age of 39 years (range 16-68). The diagnosis was performed with MRI in 53 patients, and angiography in 2. The outcome was assessed with the modified Rankin scale (mRs). After a median follow-up of 36 months (range: 12-60), 45 patients were independent (mRS 0-2), and 10 were dependent or dead (mRS 3-6). Of 48 survivors, 7 had seizures, 6 motor deficits, 5 visual field defects, 29 headache (migraine in 14, tension headache in 13, other in 2). The logistic regression analysis found focal deficits and cancer at time of diagnosis, as independent predictors of dependence or death at year 3, and isolated intra-cranial hypertension as an independent predictor of survival and independence. Mortality rates are low in the absence of cancer and focal deficits, and more than 80 % of survivors are independent after 3 years. However, 3/4 of survivors have residual symptoms. Therefore, despite a low mortality rate, CVT remains a serious disorder.
Abstract: Magnetic resonance imaging (MRI) provides valuable pathophysiological information during the very first hours of cerebral ischemia. However, the reliability of prime-time MRI in the setting of emergency care remains unknown.
Abstract: 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.
Abstract: Peripheral cerebellar artery aneurysms are rare and difficult to treat surgically. We report the angiographic results and the clinical outcomes for eight patients treated by embolization for peripheral cerebellar artery aneurysms.
Abstract: We report the long-term follow-up of 18 patients with giant aneurysms of the internal carotid artery (ICA) referred for endovascular occlusion of the parent vessel. There were 10 aneurysms involving the infra- and/or supraclinoid cavernous segment, six the ophthalmic segment, one the petrous segment and one the bifurcation. One patient who did not tolerate test occlusion was treated medically. Clinical and imaging follow-up were obtained in 16 patients for a mean of 30 months, range 6-80 months. Endovascular treatment led to excellent clinical outcome in 16 patients. One 34-year-old woman, who presented with subarachnoid haemorrhage (SAH), died from bilateral middle cerebral artery infarcts due to severe vasospasm 4 days after treatment. The patient treated medically died from SAH. Long-term imaging follow-up in 16 patients revealed a markedly smaller aneurysm sac in all cases.
Abstract: Devic's neuromyelitis optica (NMO) associates optic neuritis and myelitis without any other neurological signs. Many patients with NMO may be diagnosed as having multiple sclerosis (MS), optic neuritis and myelitis being the inaugural symptom in 20% and 5% of MS cases, respectively. The aim of our study was to compare a new NMO cohort with recent studies and to try to determine the place of NMO in the spectrum of MS. We retrospectively studied 13 patients with a complete diagnostic workup for NMO. We compared our data with the most recent studies on NMO and with the criteria proposed by Wingerchuck et al. [Neurology 53 (1999) 1107]. We also determined whether these patients fulfilled the diagnostic criteria for MS. Thirteen patients (10 women and three men, with a mean age of 37.4 years) were included in the study. We found similar results to previously published data, except for an association with vasculitis in 38% of our cases. All but three of the patients fulfilled the clinical criteria for MS and two patients fulfilled both clinical and MRI criteria for MS. However, if we applied more restrictive criteria concerning spinal cord and brain MRI and CSF, none of our NMO patients fulfilled the MS diagnostic criteria. NMO might therefore be differentiated from MS by the application of more stringent criteria. Furthermore, all NMO patients should be investigated for vasculitis, even those with no history of systemic disease.
Abstract: A 25-year-old immunocompetent male heroin addict was admitted for acute confusion associated with gait disorders of three month duration. The diagnosis was meningoencephalomyeloradiculitis secondary to Candida albicans infection. Outcome was good after a 6-month regimen with antifungal drugs. Neurological complications of Candida albicans infection are rare and prognosis is generally poor. This case report illustrates diagnostic and therapeutic difficulties encountered.
Abstract: Our purpose was to assess the usefulness of diffusion- and perfusion-weighted MRI for the detection of ischaemic brain damage in patients with suspected vasospasm after subarachnoid haemorrhage (SAH). We studied 11 patients admitted with a ruptured aneurysm of the anterior circulation and suspected of intracranial vasospasm on clinical examination and transcranial Doppler sonography (TCD). All were investigated by technetium-hexamethyl-propylene amine oxime (Tc-HMPAO) single photon emission computed tomography (SPECT) and diffusion and perfusion-weighted MRI (DWI, PWI) within 2 weeks of their SAH. Trace images and TTP maps were interpreted by two examiners and compared with clinical and imaging follow-up. PWI revealed an area of slowed flow in seven patients, including four with major and three with minor hypoperfusion on SPECT. In two patients, PWI did not demonstrate any abnormality, while SPECT revealed major hypoperfusion in one and a minor deficit hypoperfusion in the other. Two patients with high signal on DWI had a permanent neurological deficit.
Abstract: True malformations of the vein of Galen are usually diagnosed within the first weeks of life. They represent less than 1 p. 100 of the cerebral arteriovenous malformations. These true malformations are exceptional in adults but should be known as an endovascular treatment could be performed. The most frequent clinical presentation is a severe cardiac failure leading to death. We report a giant arteriovenous malformation of the vein of Galen in a right-handed, 50 year-old man. During childhood, he suffered from a compensated cardiac failure which remained of unknown cause. Neurological examination showed kinetic and static cerebellar syndrome and a Parinaud syndrome. A cerebral MRI scan revealed a giant vascular malformation of the vein of Galen with a normal posterior fossa. The angiography enabled the diagnosis of a true malformation of the vein of Galen in its choroidian form. Its high blood flow entails cardiac failure because of a steal phenomenon. An endovascular treatment was declined because of numerous arterial afferences and the potential risks of peroperative haemorrhage.
Abstract: The long-term outcome of patients treated with Guglielmi detachable coils (GDCs) remains unknown and is being evaluated. We sought to assess the feasibility and utility of contrast-enhanced MR angiography in the follow-up of anterior communicating artery (AcomA) aneurysms treated with GDCs.
Abstract: Few studies have been devoted to the natural history of cervical artery dissection (CAD). This review shows that apart from neurological damage due to initial stroke, the prognosis of DAC is good. Indeed, the risk of recurrent DAC or recurrent stroke is very low, under 1% per year in patients without typical connective tissue disease. Patients with connective tissue disease (Ehlers Danlos syndrome or Marfan syndrome) or familial history of arterial dissection have an increased risk of recurrent CAD. However, the number of cases due to these diseases remains very low. The other risk factors for recurrent CAD or stroke remain unknown. The benefit of antithrombotic treatments at the acute phase of CAD or for secondary prevention has been never assessed in a randomized clinical trial.
Abstract: Autonomic dysfunction has rarely been studied in patients suffering from multiple sclerosis (MS). Some hypotheses have concerned the pathophysiology, especially with regard to a possible spinal cord origin. However, there have been no previous studies on autonomic dysfunction in MS and spinal cord lesions. This study assessed the frequency of autonomic dysfunction (AD) in MS and the correlation to spinal cord magnetic resonance imaging (MRI) findings. We prospectively studied 75 MS patients (25 with relapsing-remitting forms, 25 with secondary progressive forms and 25 with primary progressive forms). We performed sympathetic skin response, R-R interval variability and orthostatic hypotension testing. Spinal cord MRI was performed to detect demyelinating lesions (sagittal and axial plane) or spinal cord atrophy. Clinical and laboratory evidence of AD was found in 84% and 56% of MS patients, respectively. The correlation of the latter with disability was evaluated using the Extended Disability Status Scale. AD was more frequent in primary progressive MS than in the other two forms. AD was correlated with spinal cord cross-sectional area reduction but not with spinal cord hyperintensities. This study confirms that the frequency of AD in MS, especially in primary progressive forms, has until now been underestimated. Furthermore, AD appears to be more closely related to axonal loss, as demonstrated by spinal cord atrophy, than to demyelinating lesions.
Abstract: Conventional angiography is considered to be gold standard for evaluating the degree of carotid artery stenosis. However, this technique carries a risk of complications. Thus, noninvasive techniques have been developed to avoid conventional angiography. Among these techniques, duplex sonography certainly constitutes the most attractive method, providing both morphological and hemodynamic data by combining different acquisition modalities. Contrast-enhanced MR angiography (MRA) is a recent development providing information on the intracranial and cervical vascularization in a short acquisition time. Previous studies have showed the reliability of this technique to detect severe carotid stenosis. Helicoidal CT is a third noninvasive method providing a reliable evaluation of carotid artery stenosis by analyzing both the axial CT images and the 3D reconstruction. However, CT angiography requires a radiation does and injection of an iodinated contrast agent. Moreover, the surrounding venous and bone structures may obscure evaluation of the arterial lumen.
Abstract: The main aetiologies of acute myelopathy (AM) are: multiple sclerosis, systemic disease (SD), spinal cord infarct (SCI), parainfectious myelopathy (PIM) and delayed radiation myelopathy (DRM). Although a large amount of data have been published for each individual aetiology, comparison studies are scarce. The aim of this study was to assess the various aetiological and outcome profiles of AM. We studied 79 cases: 34 (43%) in multiple sclerosis; 13 (16.5%) in SD; 11 (14%) in SCI; five (6%) in PIM; and three (4%) in DRM. Myelopathies were of unknown origin in 13 (16.5%) patients. We evaluated clinical, spinal cord and brain MRI, CSF and evoked potentials data at admission, MRI outcome at 6 months and clinical outcome at 12 months. A statistical comparison of clinical, laboratory and outcome data was only performed between multiple sclerosis, SD and SCI patients due to the small number of cases in the other groups. A motor deficit was more frequent in SD and SCI than in multiple sclerosis where initial symptoms were predominantly sensory (P < 0.001). Spinal cord MRI showed lateral or posterior lesions of less than two vertebral levels in multiple sclerosis, in contrast to SD and SCI, where lesions involved more vertebral levels and were centromedullar (P < 0.001). Brain MRI was most frequently abnormal in multiple sclerosis (68%), but was also abnormal in 31% of SD patients (P < 0.05). Oligoclonal bands in CSF were more frequent in multiple sclerosis than in SD (P < 0.001) and were never found in SCI. Clinical outcome at 12 months was good in 88% of multiple sclerosis cases, and poor or fair in 91% of SCI and 77% of SD. Aetiologies of AM may be differentiated on the basis of clinical, spinal cord and brain MRI, CSF and outcome data, and allow a probable diagnosis to be made in previously undetermined cases. These findings may have therapeutic implications for cases with a questionable diagnosis.
Abstract: Autonomic nervous system disturbances such as pupillary abnormalities have rarely been evaluated in multiple sclerosis (MS). However, pupillary impairment is not uncommon in MS and its origin is still unclear. The aim of this study was to investigate pupillary disturbances in MS and to try to correlate pupillary defects with spinal cord and brainstem magnetic resonance imaging (MRI) findings. We prospectively studied 45 MS patients and 30 normal subjects. METHODS: The pupillary contraction latency and the amplitude of contraction were recorded by pupillometry. We also determined afferent and efferent pathway defects by comparing the direct and consensual pupillary reflexes. We evaluated brainstem and spinal cord demyelinating lesions and spinal cord cross-sectional area on MRI. At least one pupillometric parameters were significantly impaired in 60% of patients and in none of the controls. We did not find any correlation between pupillary defect and demyelinating lesions on MRI. The most frequent abnormality was efferent pathway shift and this was correlated with spinal cord atrophy (P<0.02). These results confirm that the autonomic nervous system, and especially pupillary function, is frequently impaired in MS. The parasympathetic system is most commonly affected and this is most likely linked to axonal loss (demonstrated by spinal cord atrophy) rather than to demyelinating lesions.
Abstract: Several acquisition strategies may be used for imaging supraaortic vessels by using contrast-enhanced MR angiography. The purpose of this study was to assess the effect of voxel size on image quality of MR angiograms.
Abstract: Spinal cord magnetic resonance imaging (MRI) is of particular interest in the management of multiple sclerosis (MS) especially in primary progressive forms. Most of the demyelinating lesions are located in the cervical or dorsal cord. Spinal cord area reduction has been recently correlated with the progression of disability (Losseff et al., 1996, Lycklama a Nijeholt et al., 1998). The aim of this study was to confirm this first result, to assess the reproducibility of this method and to correlate demyelinating lesions with spinal cord area reduction. Fifty two patients were included and compared with 15 controls (normal subjects). T2 Sagittal and axial plane images were performed to localized hypersignal lesions. Spinal cord area was obtained by a volume acquired inversion prepared fast spoiled gradient echo acquisition (MP-Rage) sequence. We compared the mean area value with clinical parameters (age, course of the disease, expanded disability status scale ¿EDSS) and with the number and location of demyelinating lesions. Demyelinating lesions were found in 82p.100 of MS patients and in none of controls. Mean spinal cord area was closely similar to Losseff et al. (1996) results and was reduced compared with controls (p<0.001). Spinal cord reduction was correlated with disability, studied by the EDSS. Furthermore, no correlation was found between demyelinating lesions and spinal cord area reduction. This study confirms the interest of spinal cord area mesurement in MS. Spinal cord atrophy is a reliable marker for axonal loss. This method should be of particular interest for the follow-up of axonal loss in thepeutic trials especially in primary progressive MS.
Abstract: A 38 year-old woman, without previous medical history, presented, since 1993, several paraplegic fits carrying herself progressively through to a severe paraplegia. Diagnoses successively proposed were spinal cord compressions by slipped discs, spinal cord infarct and multiple sclerosis. In November 1998, the patient presented back pain and fever. Spinal cord magnetic resonance imaging (MRI) revealed a mildly enlarged dorsal cord with signal abnormalities. The lesions were isointense on T1-weighted images, hyperintense on T2-weighted images and showed a ringlike contrast enhancement. A lumbar puncture showed a trouble cerebrospinal fluid (CSF) with leucocytes 600/mm(3) (85 p.100 polynuclear), protein 6.7 g/l, glucose 0.26 g/l, chloride 109 mmol/l. The patient was first treated with parenteral unspecific antibiotherapy. Microbiological studies of blood and CSF were negative. CSF examination with polymerase chain reaction (PCR) was positive for Mycobacterium tuberculosis. Clinical (pain and fever) symptoms and CSF abnormalities decreased after antituberculous treatment. However, paraparesis remain severe. Spinal tuberculous localizations often lead to diagnostic and therapeutic errors. Improvement of spinal cord MRI sequences and using of PCR technics in CSF would contribute to reduce these difficulties.
Abstract: Ventricular repolarization dysfunction has recently been reported in multiple sclerosis (MS). We evaluated ventricular repolarization dysfunction in 52 MS patients and looked for a relationship between corrected QT (QTc) abnormalities (i.e., abnormalities of QT intervals corrected for rate) and spinal cord magnetic resonance imaging (MRI) findings. QTc intervals were increased in MS patients compared with controls (P < 0.01) and were correlated with a reduction of spinal cord area (P < 0.01). QTc abnormalities in MS were thus associated with axonal loss, reflected by spinal cord atrophy, rather than demyelination.
Abstract: This study sought to assess the feasibility of a contrast-enhanced three-dimensional (3D) magnetic resonance (MR) angiographic sequence for imaging the cervical arteries.
Abstract: The use of MR angiography (MRA) with injection of contrast medium enables imaging of a large volume with a very short acquisition time, providing angiographic images similar to those obtained with catheter angiography. This makes possible investigation of patients in the acute phase of stroke, with examination of the entire length of the cervical arteries from the aortic arch to the circle of Willis. However, the parameters of the sequence must be carefully chosen to optimise image quality, with a compromise between spatial resolution, acquisition time and image contrast. An overview of the technical aspects is presented, including current developments. Different protocol strategies are discussed, including their advantages and limits. Finally, we review the preliminary results of contrast-enhanced MRA for assessment of atherosclerotic lesions of supra-aortic vessels.
Abstract: Sixty-nine patients with cervical atherosclerotic disease were evaluated by Magnetic Resonance (MR) angiography using a coronal 3D gradient echo gadolinium enhanced sequence. The image quality was evaluated for each artery and ostium on MIP reconstructions. A comparison with conventional angiography was achieved in 27 patients. All MR examinations were assessable; a second injection was performed in ten patients. All carotid bifurcations were visualized. The ostium of the common carotid artery was not assessable in 44% of cases due to the limited coverage. The evaluation of the posterior circulation was good in 90% of cases. The agreement between MR angiography and conventional angiography was good despite a tendency to overestimate moderate stenoses. Stenoses greater than 70%, carotid occlusions and vertebral stenoses greater than 50% were correctly detected.
