COVID-19 Neurologic Complication with CNS Vasculitis-Like Pattern.

Coronavirus disease 2019 (COVID-19) is a viral infection caused by the Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2), which spreads rapidly from person to person and manifests in most symptomatic patients as a respiratory illness, similar to prior SARS viruses. Neurologic manifestations of COVID-19 are uncommon; those so far reported include encephalopathy, stroke from large-vessel occlusion, and polyneuropathy. We report a unique neurologic complication of COVID-19 in a patient who had extensive cerebral small-vessel ischemic lesions resembling cerebral vasculitis in a characteristic combined imaging pattern of ischemia, hemorrhage, and punctuate postcontrast enhancement. Also, a characteristic lower extremity skin rash was present in our patient. Our observation lends support to the increasingly suspected mechanism of "endotheliitis" associated with this novel coronavirus.

Role of flow magnetic resonance imaging in the monitoring of facial allotransplantations: preliminary results on graft vasculopathy.

Chronic vascular rejection characterized by the myointimal proliferation of smooth muscle cells that progressively obstruct the arterial graft lumen may become the main cause of long-term graft loss in vascularized composite allotransplantation (VCA), as observed in solid organ transplantation. As such, new diagnostic tools are required. The objective of this study was to evaluate the usefulness of flow magnetic resonance imaging (MRI) in the qualitative and quantitative monitoring of VCA in three patients transplanted between 2005 and 2012. Seven flow MRI acquisitions were performed concurrently with standardized clinical and histological monitoring between 2015 and 2017. A progressive reduction in the average flow rate and intraluminal diameter of the arterial pedicle of the grafts was demonstrated. During follow-up, two patients developed chronic vascular rejection requiring partial resection of the graft. For these patients, flow MRI acquisitions were characterized by a significant reduction in vascular signal, with a reduction in intravascular flow prior to anatomical injury. The results of this study confirm the feasibility of reproducible, non-invasive, and non-operator-dependent morphometric and haemodynamic radiological analysis, providing clinicians with new information on the vascular status of VCA over time and offering the prospect of an imaging technique specific to vascular outflow.

Contribution of flow MRI in the therapeutic management of middle face high flow arteriovenous malformation: A case report.

BACKROUND: The radiosurgical management of high flow arteriovenous malformations (HFAVM) in the "destructive" stage requires a precise hemodynamic and anatomical assessment. PATIENT AND METHODS/CASE REPORT: We report the case of a 32 years-old patient with a large ulcerated face HFAVM, on which Doppler ultrasound was impossible to perform. We show that, by combining 3D PCA and 2D CINE PC-MRI sequences, magnetic resonance imaging is capable to provide a complete morphometric and velocimetric mapping of the nidus and feeding arteries of the HFAVM. CONCLUSION: Although Doppler ultrasound is the reference examination in the HFAVM, Flow MRI without contrast agent provides an advantageous alternative to assess vascular pathologies and choose the therapeutic strategy.

Perfusion magnetic resonance imaging in pediatric brain tumors.

PURPOSE: The use of DSC-MR imaging in pediatric neuroradiology is gradually growing. However, the number of studies listed in the literature remains limited. We propose to assess the perfusion and permeability parameters in pediatric brain tumor grading. METHODS: Thirty children with a brain tumor having benefited from a DSC-MR perfusion sequence have been retrospectively explored. Relative CBF and CBV were computed on the ROI with the largest lesion coverage. Assessment of the lesion's permeability was also performed through the semi-quantitative PSR parameter and the K2 model-based parameter on the whole-lesion ROI and a reduced ROI drawn on the permeability maps. A statistical comparison of high- and low-grade groups (HG, LG) as well as a ROC analysis was performed on the histogram-based parameters. RESULTS: Our results showed a statistically significant difference between LG and HG groups for mean rCBV (p < 10-3), rCBF (p < 10-3), and for PSR (p = 0.03) but not for the K2 factor (p = 0.5). However, the ratio K2/PSR was shown to be a strong discriminating factor between the two groups of lesions (p < 10-3). For rCBV and rCBF indicators, high values of ROC AUC were obtained (> 0.9) and mean value thresholds were observed at 1.07 and 1.03, respectively. For K2/PSR in the reduced area, AUC was also superior to 0.9. CONCLUSIONS: The implementation of a dynamic T2* perfusion sequence provided reliable results using an objective whole-lesion ROI. Perfusion parameters as well as a new permeability indicator could efficiently discriminate high-grade from low-grade lesions in the pediatric population.

[(18)F]-fluoro-L-thymidine PET and advanced MRI for preoperative grading of gliomas.

PURPOSE: Conventional MRI based on contrast enhancement is often not sufficient in differentiating grade II from grade III and grade III from grade IV diffuse gliomas. We assessed advanced MRI, MR spectroscopy and [(18)F]-fluoro-l-thymidine ([(18)F]-FLT) PET as tools to overcome these limitations. METHODS: In this prospective study, thirty-nine patients with diffuse gliomas of grades II, III or IV underwent conventional MRI, perfusion, diffusion, proton MR spectroscopy ((1)H-MRS) and [(18)F]-FLT-PET imaging before surgery. Relative cerebral blood volume (rCBV), apparent diffusion coefficient (ADC), Cho/Cr, NAA/Cr, Cho/NAA and FLT-SUV were compared between grades. RESULTS: Cho/Cr showed significant differences between grade II and grade III gliomas (p = 0.03). To discriminate grade II from grade IV and grade III from grade IV gliomas, the most relevant parameter was the maximum value of [(18)F]-FLT uptake FLTmax (respectively, p < 0.001 and p < 0.0001). The parameter showing the best correlation with the grade was the mean value of [(18)F]-FLT uptake FLTmean (R(2) = 0.36, p < 0.0001) and FLTmax (R(2) = 0.5, p < 0.0001). CONCLUSION: Whereas advanced MRI parameters give indications for the grading of gliomas, the addition of [(18)F]-FLT-PET could be of interest for the accurate preoperative classification of diffuse gliomas, particularly for identification of doubtful grade III and IV gliomas.

Hippocampal modifications in transient global amnesia.

Transient global amnesia (TGA) is an acute and transient syndrome with a remarkably stereotypical set of signs and symptoms. It is characterized by the abrupt onset (no forewarning) of massive episodic memory impairment, both anterograde and retrograde. Ever since it was first described, TGA has fascinated neurologists and other memory experts, and in recent years, there has been a surge of neuroimaging studies seeking to pin down the brain dysfunction responsible for it. Several pathophysiological hypotheses have been put forward, including the short-lived suggestion of an epileptic mechanism. All the available data indicate that the brain modifications are reversible, and that the mechanism behind TGA is of a functional nature. However, while diffusion-weighted imaging studies have clearly identified the hippocampus and, more specifically, the CA1 area, as the locus of brain modifications associated with TGA, researchers have yet to determine whether the origin of the mechanism is vascular or neurochemical. Spectroscopy may provide a means of settling this issue once and for all.

REBECA: a phase I study of bevacizumab and whole-brain radiation therapy for the treatment of brain metastasis from solid tumours.

BACKGROUND: Brain metastases (BMs) are associated with a poor prognosis. Standard treatment comprises whole-brain radiation therapy (WBRT). As neo-angiogenesis is crucial in BM growth, combining angiogenesis inhibitors such as bevacizumab with radiotherapy is of interest. We aimed to identify the optimal regimen of bevacizumab combined with WBRT for BM for phase II evaluation and provide preliminary efficacy data. PATIENTS AND METHODS: In this multicentre single-arm phase I study with a 3 + 3 dose-escalation design, patients with unresectable BM from solid tumours received three cycles of bevacizumab at escalating doses [5, 10 and 15 mg/kg every 2 weeks at dose levels (DL) 0, 1 and 2, respectively] and WBRT (30 Gy/15 fractions/3 weeks) administered from day 15. DL3 consisted of bevacizumab 15 mg/kg with WBRT from day 15 in 30 Gy/10 fractions/2 weeks. Safety was evaluated using NCI-CTCAE version 3. BM response (RECIST 1.1) was assessed by magnetic resonance imaging at 6 weeks and 3 months after WBRT. RESULTS: Nineteen patients were treated, of whom 13 had breast cancer. There were no DLTs. Grade 1-2 in-field and out-field toxicities occurred for five and nine patients across all DLs, respectively, including three and six patients (including one patient with both, so eight patients overall) of nine patients in DL3. One patient experienced BM progression during treatment (DL0). At the 3-month post-treatment assessment, 10 patients showed a BM response: one of three treated at DL0, one of three at DL1, two of three at DL2 and six of seven at DL3, including one complete response. BM progression occurred in five patients, resulting in two deaths. The remaining patient died from extracranial disease progression. CONCLUSION: Bevacizumab combined with WBRT appears to be a tolerable treatment of BM. DL3 warrants further efficacy evaluation based on the favourable safety/efficacy balance. ClinicalTrials.gov Identifier: NCT01332929.

Five-Year Longitudinal MRI Follow-up and (1)H Single Voxel MRS in 14 patients with Gliomatosis Treated with Temodal, Radiotherapy and Antiangiogenic Therapy.

Gliomatosis cerebri (GC) is a challenging tumor, considered to have a poor prognosis and poor response to treatments. The purpose of this study is to better understand glial tumor metabolism and post chemotherapy, radiotherapy and antiangiogenic variations in a longitudinal study to determine cerebral variation in MRS area, amplitude, and ratios of metabolites and spectral profiles during a five year longitudinal follow-up in 14 patients with gliomatosis without initial hyperperfusion and treated with chemotherapy (Temozolomide (Temodal(®))), radiotherapy and subsequent antiangiogenic therapy. The study also aimed to detect changes in infiltration, proliferation, lipids or glycolytic metabolism, as these changes could be monitored longitudinally in humans with glial brain tumors (low and high grade) after therapy, using conventional magnetic resonance imaging (MRI), spectroscopy (MRS) and MR perfusion. Most patients had first initial clinical and MRS improvement and stable MRI. After 12 to 24 chemotherapy treatment cycles MRS usually showed an increase in the Cho/Cr ratio (proliferation) and sometimes contrast enhancements. Later, the patients showed clinical deterioration and radiotherapy was started. There was an improvement with radiotherapy that lasted nine to 18 months. This was followed by a worsening that led to try antiangiogenic therapy. Later in the evolution for three patients with hyperperfusion this symptom disappeared, but proliferation, infiltration and glycolytic metabolism remained at a high level. Spectroscopic and metabolic changes often occur well before clinical deterioration and sometimes before improvement. Therefore, MRS could be more sensitive and could detect changes earlier than MRI and is sometimes predictive. Despite the difficulty, the variability and unknown factors, these repeated measurements give us a better insight into the nature of the different processes, tumor progression and could lead to better understanding of therapeutic response.

The human parahippocampal region: I. Temporal pole cytoarchitectonic and MRI correlation.

The temporal pole (TP) is the rostralmost portion of the human temporal lobe. Characteristically, it is only present in human and nonhuman primates. TP has been implicated in different cognitive functions such as emotion, attention, behavior, and memory, based on functional studies performed in healthy controls and patients with neurodegenerative diseases through its anatomical connections (amygdala, pulvinar, orbitofrontal cortex). TP was originally described as a single uniform area by Brodmann area 38, and von Economo (area TG of von Economo and Koskinas), and little information on its cytoarchitectonics is known in humans. We hypothesize that 1) TP is not a homogenous area and we aim first at fixating the precise extent and limits of temporopolar cortex (TPC) with adjacent fields and 2) its structure can be correlated with structural magnetic resonance images. We describe here the macroscopic characteristics and cytoarchitecture as two subfields, a medial and a lateral area, that constitute TPC also noticeable in 2D and 3D reconstructions. Our findings suggest that the human TP is a heterogeneous region formed exclusively by TPC for about 7 mm of the temporal tip, and that becomes progressively restricted to the medial and ventral sides of the TP. This cortical area presents topographical and structural features in common with nonhuman primates, which suggests an evolutionary development in human species.

[Current management of brain metastases]. / Traitement actuel des métastases cérébrales.

INTRODUCTION: Cerebral metastases occur in 15 to 20% of cancers and their incidence is increasing. The majority occur at an advanced stage of the disease, but metastasis may be the inaugural sign of cancer. The aim of treatments, which are often palliative, is to preserve the neurological status of the patient with the best quality of life. STATE OF ART: Corticosteroids are widely used for symptomatic palliation, requiring close monitoring and regular dose adaptation. Antiepileptic drugs should be given only for patients who have had a seizure. In case of multiple cerebral metastases occurring at an advanced stage of the disease, whole brain radiation is the most effective therapy for rapid symptom control. However, radiotherapy moderately improves overall survival, which often depends on the progression of disseminated systemic disease. On the contrary, surgery is indicated in case of a solitary metastasis, particularly when the patient is young (less than 65 years), with good general status (Karnofsky greater than 70), and when the systemic disease is under control. Radiosurgery offers an attractive alternative for these patients with good prognostic factors and a small number of cerebral metastases (< or = 4). PERSPECTIVES: Chemotherapy, considered in the past as not effective, is taking on a more important place in patients with multiple nonthreatening metastases from chemosensitive cancers (breast, testes...). Radiosurgery and whole brain radiotherapy are complementary techniques. Their respective role in the management of multiple metastases (< 4) remains to be further investigated. CONCLUSIONS: Therapeutic options are increasingly effective to improve the functional prognosis of patients with cerebral metastases. Ideally, a multidisciplinary assessment offers the best choice of therapeutic modalities.

[Quantitative relationships between ADC and perfusion changes in acute ischemic stroke using combined diffusion-weighted imaging and perfusion MR (DWI/PMR)]. / Relation quantitative des modifications de la diffusion et de la perfusion au sein du parenchyme cerebral au cours de l'accident ischémique aigu.

UNLABELLED: MR-based diffusion- and perfusion-weighted imaging (DWI/PWI) has become the standard imaging technique to assess the individual brain pathophysiological status in acute ischemic stroke. The finding of a "mismatch" with larger PWI than DWI abnormality is thought to reflect the presence of tissue at-risk of infarction, i.e., penumbra. However, there has been no detailed study of the quantitative relationships between perfusion and diffusion changes in stroke patients. According to the experimental concept of penumbra, the ADC would be expected to remain unchanged despite decreasing perfusion until a critical threshold is reached. We have tested this hypothesis directly in man. METHODS: DWI/PWI was performed in 7 patients with MCA territory stroke within 4-10 hrs from onset. Mismatch was defined on diffusion and rMTT maps, and circular ROIs were positioned within the ADC lesion (D), the mismatch area (M), and the normal appearing cortex (N); mirror ROIs were also obtained, and affected/unaffected ratios for ADC and rCBF were computed for each ROI. RESULTS: The mean (+/-1 SD) ADC ratios were 0.60 +/- 0.09, 0.95 +/- 0.10 and 1.02 +/- 0.04 in L, M and N, respectively; the corresponding rCBF ratios were 0.32 +/- 0.12, 0.75 +/- 0.14 and 0.97 +/- 0.09, respectively. The relationship was non-linear, with the rCBF but not the ADC ratio for M being significantly lower (p < 0.01) than that for N. A threshold for decline in ADC was apparent around 0.50 rCBF ratio. COMMENT: These results directly document in man that the ADC declines only after hypoperfusion has reached a certain degree (about 50%), consistent with the concept of the ischaemic penumbra.

Fuzzy modelling of different tumorous cerebral tissues on MRI images based on fusion of feature information.

A fuzzy modelling approach is being proposed in this paper to estimate the model of tumorous cerebral tissues on MRI images. According to the graduality of description of neuro-radiologists, two tables have been combined to address two types of potential categories of glioma characteristics one is the array of different tissues versus gray level, and the other is the possibility of different tissues belonging to tumor. A hierarchical estimation structure has been proposed to estimate the models of tumorous cerebral tissues on MRI images by the fusion of this a priori knowledge. Through the model outline drawing, adjusting and parameters estimation, the result has shown that this is an efficient modelling method.

Clinical, biochemical, magnetic resonance imaging (MRI) and proton magnetic resonance spectroscopy (1H MRS) findings in a fourth case of combined D- and L-2 hydroxyglutaric aciduria.

We report the fourth case of combined D-and L-2-hydroxyglutaric aciduria presenting with neonatal encephalopathy and subependymal cysts.

MRI texture analysis on texture test objects, normal brain and intracranial tumors.

Texture analysis was performed in three different MRI units on T1 and T2-weighted MR images from 10 healthy volunteers and 63 patients with histologically confirmed intracranial tumors. The goal of this study was a multicenter evaluation of the usefulness of this quantitative approach for the characterization of healthy and pathologic human brain tissues (white matter, gray matter, cerebrospinal fluid, tumors and edema). Each selected brain region of interest was characterized with both its mean gray level values and several texture parameters. Multivariate statistical analyses were then applied in order to discriminate each brain tissue type represented by its own set of texture parameters. Texture analysis was previously performed on test objects to evaluate the method dependence on acquisition parameters and consequently the interest of a multicenter evaluation. Even obtained on different sites with their own acquisition routine protocol, MR brain images contain textural features that can reveal discriminant factors for tissue classification and image segmentation. It can also offer additional information in case of undetermined diagnosis or to develop a more accurate tumor grading.

"Protected" wallstenting of atheromatous stenoses at the carotid bifurcation.

SUMMARY: Atheromatous stenoses at the carotid bifurcation were treated by angioplasty and Wallstenting with cerebral protection obtained in most cases by temporary occlusion of the internal carotid artery. 287 carotid stenoses were treated in 233 patients. The stenosis was symptomatic in 79% of cases. All patients presented either a stenosis of >70% with significant impairment of the cerebral circulation (281 cases) or a symptomatic ulcerated plaque (six cases). A self-mounted protection system was used in 177 cases, the Percusurge Guardwire protection device in 98 cases an EPI filter in 12 cases. There was a contralateral internal carotid occlusion in 13% of cases. A combined stenting (vertebral, siphon, subclavian) was performed in 14% of cases. A Rolling membrane Wallstent was used in 84 patients, a first generation Easy Wallstent in 38 cases, a "Carotid" Easy Wallstent 35 in 55 cases and monorail 14 in 110 cases. Full opening of the stenosis was obtained in 98% of patients with correction of the arterial curve and improvement of the cerebral vascular supply. There were 0.7% cases with transient symptomatic neurological complications and 2% with permanent sequelae mainly related to avoidable inadequacy in flushing or to the insufficient radial force of the first generation Easy Wallstent. There were no per and one post-procedural cardiac complication (0.6%) in the s165 cases performed with the "Carotid" Easy Wallstent. Follow-up angiograms showed 0.7% of restenoses. Still in evolution, endovascular treatment of atheromatous stenoses at the carotid bifurcation with cerebral protection and stenting is a promising alternative technique to surgery. The association of Carotid Easy Wallstent 14 monorail and Percusurge Guardwire appears to be currently satisfactory.

Acquisition, segmentation and tracking of the cerebral vascular tree on 3D magnetic resonance angiography images.

This paper presents a method for the detection, representation and visualisation of the cerebral vascular tree and its application to magnetic resonance angiography (MRA) images. The detection method is an iterative tracking of the vessel centreline with subvoxel accuracy and precise orientation estimation. This tracking algorithm deals with forks. Centrelines of the vessels are modelled by second-order B-spline. This method is used to obtain a high-level description of the whole vascular network. Applications to real angiographic data are presented. An MRA sequence has been designed, and a global segmentation of the whole vascular tree is realised in three steps. Applications of this work are accurate 3D representation of the vessel centreline and of the vascular tree, and visualisation. The tracking process is also successfully applied to 3D contrast enhanced MR digital subtracted angiography (3D-CE-MRA) of the inferior member vessels. In addition, detection of artery stenosis for routine clinical use is possible due to the high precision of the tracking algorithm.

Atrophy of the corpus callosum correlates with white matter lesions in patients with cerebral ischaemia.

Many studies of white matter high signal (WMHS) on T2-weighted MRI have disclosed that it is related to cerebral ischaemia and to brain atrophy. Atrophy of the corpus callosum (CC) has also been studied in relation to ischaemia. Our objective was to test the hypothesis that CC atrophy could be due to ischaemia. We therefore assessed CC, WMHS and brain atrophy in patients with risk factors without strokes (the risk factor group) and in those with infarcts (the infarct group), to investigate the relationships between these factors. We studied 30 patients in the infarct group, 14 in the risk factor group, and 29 normal subjects. Using axial T1-weighted MRI, cortical atrophy and ventricular enlargement (brain atrophy) were visually rated. Using axial T2-weighted MRI, WMHS was assessed in three categories: periventricular symmetrical, periventricular asymmetrical and subcortical. Using the mid-sagittal T1-weighted image, the CC was measured in its anterior, posterior, mid-anterior and mid-posterior portions. In the normal group, no correlations were noted between parameters. In the infarct group, there were significant correlations between CC and brain atrophy, and between CC atrophy and WMHS. After removing the effects of age, gender and brain atrophy, significant correlations were noted between some CC measures and subcortical WMHS. In the risk factor group, there were significant correlations between CC and brain atrophy and between CC atrophy and WMHS. After allowance for age, gender and brain atrophy, significant correlations between some CC measures and periventricular WMHS remained. The hypothesis that CC atrophy could be due to cerebral ischaemia was supported by other analyses. Namely, for correlations between the extent of infarcts and partial CC atrophy in patients with anterior middle cerebral artery (MCA) and with posterior MCA infarcts, there were significant correlations between the extent of infarct and mid-anterior CC atrophy in the former, and posterior CC atrophy in the latter. Our findings could indicate that CC atrophy is associated with cerebral ischaemia.

[Magnetic resonance spectroscopy in schizophrenia]. / Apport de la spectroscopie par résonance magnétique dans la schizophrénie.

Numerous studies have shown alterations of some structures and/or cerebral functions in patients with schizophrenia. However, the nature of the neurobiological process which could be at the origin of schizophrenic symptoms is still unknown. Magnetic resonance spectroscopy (MRS) is a unique technique which allows us to estimate the concentrations of endogenous substances which contain natural paramagnetic nuclei such as phosphorus (31P) and hydrogen (proton or 1H). The non invasive character of this technique, the absence of side effects, and the possibility of repetitive evaluations allowing for longitudinal studies, make possible MRS studies on the in vivo cerebral metabolism in schizophrenia. The prefrontal cortex, the hippocampus and the basal ganglia have all been implicated in the pathophysiology of schizophrenia. Therefore these brain regions have been frequently studied using MRS. Both proton and phosphorus spectroscopy have been used to study schizophrenia. Compounds that are detectable by 1H-MRS include N-acetyl aspartate (NAA), choline (Cho), creatine (Cr) and myo-inositol (ml). A deficit in NAA has been consistently shown in both the frontal and temporal lobes suggesting neuronal loss in these areas. Compounds detectable by 31P-MRS include phosphomonoesters (PMEs) and phosphodiesters (PDEs), which largely represent metabolites generated by lipid turnover. 31P-MRS can also detect certain energy-containing phosphorus metabolites such as phosphocreatine (PCr) and nucleotide triphosphates. Decreased levels of PMEs and increased levels of PDEs have been consistently described in the prefrontal lobes suggesting an alteration of phospholipid metabolism. The purpose of this review is to summarize the research on schizophrenia using MRS, to show the utility of this technique in understanding schizophrenia.