F. Bonneville

Reproducibility of High-Resolution MRI for the Identification and the Quantification of Carotid Atherosclerotic Plaque Components Consequences for Prognosis Studies and Therapeutic Trials

Background and Purpose— 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. Methods— Using published criteria, 2 readers independently analyzed the carotid MRI (1.5-T MR units with a 4-channel phased-array surface coil, Machnet) of 85 consecutive patients with symptomatic (40% to 69% according to NASCET method) or asymptomatic (60% or greater) carotid artery stenosis enrolled in an ongoing prognostic study. One reader reevaluated all images. Fibrous cap was also secondarily identified independently on T2-weighted and time-of-flight (TOF) images. Results— Intraobserver agreement was substantial for the identification of calcifications (kappa [&kgr;]=0.70; 95% CI: 0.54 to 0.86) and lipid-rich/necrotic core (LR/NC) (&kgr;=0.69; 0.31 to 0.86), almost perfect for hemorrhages (&kgr;=0.82; 0.68 to 0.96), and moderate (&kgr;=0.58; 0.27 to 0.88) and fair (&kgr;=0.33; 0.09 to 0.56) for fibrous cap identification on T2-weighted and TOF images, respectively. Interobserver agreement was substantial for the identification of calcifications (&kgr;=0.74; 0.59 to 0.89) and hemorrhages (&kgr;=0.62; 0.43 to 0.81), and moderate for LR/NC (&kgr;=0.58; 0.20 to 0.95). Agreement was fair for fibrous cap identification on both T2-weighted (&kgr;=0.28; −0.03 to 0.59) and on TOF images (&kgr;=0.26; 0.04 to 0.48). Agreement between T2 and TOF images for fibrous cap identification was slight (&kgr;=0.16; 0.01 to 0.31). Intra- and interobserver reproducibility for quantitative area measurements of vessel, lumen, plaque, LR/NC, and fibrous components was high with intraclass correlation coefficients ranging from 0.73 to 0.99. However, for the LR/NC, the interval delimited by the Bland-Altman graphs was wide in comparison to the mean. Conclusions— Vessel and plaque quantification is reproducible. Reproducibility of MRI for identifying and quantifying carotid plaque components is overall acceptable, but there is still significant variability that should be taken into account in the design of prognosis studies and clinical trials. Reproducibility for fibrous cap identification needs to be improved.

Isolated Acute Nontraumatic Cortical Subarachnoid Hemorrhage

SUMMARY: Our aim was to review the etiologic background of isolated acute nontraumatic cSAH. While SAH located in the basal cisterns originates from a ruptured aneurysm in approximately 85% of cases, a broad spectrum of vascular and even nonvascular pathologies can cause acute nontraumatic SAH along the convexity. Arteriovenous malformations or fistulas, cortical venous and/or dural sinus thrombosis, and distal and proximal arteriopathies (RCVS, vasculitides, mycotic aneurysms, Moyamoya, or severe atherosclerotic carotid disease) should be sought by noninvasive imaging methods or/and conventional angiography. Additionally, PRES may also be a source of acute cSAH. In elderly patients, cSAH might be attributed to CAA if numerous hemorrhages are demonstrated by GRE T2 images. Finally, cSAH is rarely observed in nonvascular disorders, such as abscess and primitive or secondary brain tumors.

Cortical subarachnoid haemorrhage in the elderly: a recurrent event probably related to cerebral amyloid angiopathy.

Objective:  Isolated, non‐traumatic, cortical subarachnoid haemorrhage (cSAH) is a rare type of cerebrovascular disease caused by various disorders. In a few cases, especially in the elderly, no apparent cause can be identified. We report a case series of patients without apparent cause of cSAH. We aimed to determine whether cerebral amyloid angiopathy (CAA) could be a common cause of cSAH.

Intracranial solitary fibrous tumor: Imaging findings

OBJECTIVE To study the neuroimaging features of intracranial solitary fibrous tumors (ISFTs). MATERIALS AND METHODS Retrospective study of neuroimaging features of 9 consecutive histopathologically proven ISFT cases. Location, size, shape, density, signal intensity and gadolinium uptake were studied at CT and MRI. Data collected from diffusion-weighted imaging (DWI) (3 patients), perfusion imaging and MR spectroscopy (2 patients), and DSA (4 patients) were also analyzed. RESULTS The tumors most frequently arose from the intracranial meninges (7/9), while the other lesions were intraventricular. Tumor size ranged from 2.5 to 10 cm (mean=6.6 cm). They presented multilobular shape in 6/9 patients. Most ISFTs were heterogeneous (7/9) with areas of low T2 signal intensity that strongly enhanced after gadolinium administration (6/8). Erosion of the skull was present in about half of the cases (4/9). Components with decreased apparent diffusion coefficient were seen in 2/3 ISFTs on DWI. Spectroscopy revealed elevated peaks of choline and myo-inositol. MR perfusion showed features of hyperperfusion. CONCLUSION ISFT should be considered in cases of extra-axial, supratentorial, heterogeneous, hypervascular tumor. Areas of low T2 signal intensity that strongly enhance after gadolinium injection are suggestive of this diagnosis. Restricted diffusion and elevated peak of myo-inositol may be additional valuable features.

Cortical florbetapir-PET amyloid load in prodromal Alzheimer’s disease patients

BackgroundFlorbetapir (AV-45) has been shown to be a reliable tool to assess amyloid load in patients with Alzheimers disease (AD) at demential stages. Longitudinal studies also suggest that AV-45 has the ability to bind amyloid in the early stages of AD. In this study, we investigated AV-45 binding and its relation with cognitive performance in a group of patients at the prodromal stage of Alzheimers disease, recruited according to strict inclusion criteria.MethodsWe recruited patients at the prodromal stage of AD and matched control subjects. AV-45 binding was assessed using an innovative extraction method allowing quantifying uptake in the cortex only. AV-45 uptake was compared between groups in the precuneus, posterior cingulate, anterior cingulate, and orbito-frontal regions. Correlations between AV-45 uptake and cognitive performance were assessed.ResultsTwenty-two patients and 17 matched control subjects were included in the study. We report a significant increase of cortical AV-45 uptake in the patients compared to the control subjects in all regions of interest. Specific correlations were found within the patient group between mean global amyloid cortical load and cognitive performance in three different memory tests.ConclusionsThese findings suggest that at the prodromal stage of AD, memory decline is linked to an increase of cortical β-amyloid load.

Therapeutic use of CCR5 antagonists is supported by strong expression of CCR5 on CD8(+) T cells in progressive multifocal leukoencephalopathy-associated immune reconstitution inflammatory syndrome.

therapy (ART) [3], and two non-HIV-infected patients who developed PML after chemotherapy or natalizumab, one who developed PML-IRIS, and the other at high risk of PML-IRIS (supplementary table and figure). Biopsies were performed before any steroid therapy and before maraviroc was introduced for the two non-HIV-infected patients to treat or prevent PML-IRIS, with a highly favorable outcome. As a control, we collected brain autopsies from 4 HIV-infected patients who developed classic PML (without IRIS). Consistent with previous reports [3, 6], CD8+ T cells dominate the inflammatory response in HIV-infected as well as non-HIV-infected patients with inflammatory PML (Fig. 1a). In patient 2, CD68+ macrophagic/microglial cells (1,480/mm), CD20+ B cells (55/mm) and CD138+ plasma cells (241/mm) were also present in the biopsied lesion, while in patient 1, who was treated by rituximab, cells of the B cell lineage were totally absent, arguing against a necessary role for B cells and antibodies in the pathogenesis of PML-IRIS (Fig. 1i–k and data not shown). Brain lesions displayed strong infiltration by CCR5+ cells Therapeutic strategies that modulate the deleterious immune response underlying progressive multifocal leukoencephalopathy-associated immune reconstitution inflammatory syndrome (PML-IRIS) are warranted [5]. Maraviroc, an antagonist of the CCR5 chemokine receptor that entered recently the HIV armamentarium, has been suggested to be beneficial in preventing or treating PMLIRIS [1, 4]. Since chemokine receptors play an important role in inflammatory cell migration, we investigated whether the molecular target of maraviroc is expressed on pathogenic T cells infiltrating PML-IRIS lesions. Paraffinembedded brain specimens of inflammatory PML, obtained through diagnostic stereotactic brain biopsy, were analyzed from five previously described HIV-infected patients who developed PML-IRIS after initiation of antiretroviral

Intracranial Artery Stenosis or Occlusion Predicts Ischemic Recurrence after Transient Ischemic Attack

BACKGROUND AND PURPOSE: Patterns of DWI findings that predict recurrent ischemic events after TIA are well-established, but similar assessments of intracranial MRA findings are not available. We sought to determine the imaging characteristics of MRA that are predictive of early recurrent stroke/TIA in patients with TIA. MATERIALS AND METHODS: We performed a retrospective analysis of 129 consecutive patients with a clinical diagnosis of TIA in whom MR imaging was done within 24 hours of symptom onset. We calculated the sensitivity, specificity, positive predictive value, and negative predictive value of >50% stenosis or occlusion of symptomatic intracranial arteries for recurrent stroke/TIA at 7 days after TIA. We used logistic regression analysis to adjust for the clinical ABCD2 score. We performed this analysis for symptomatic steno-occlusive lesions at any site and symptomatic steno-occlusive lesions on proximal large intracranial arteries (internal carotid artery, vertebral artery, basilar artery, and circle of Willis). RESULTS: Forty-two (32.5%) patients had acute ischemic lesions on DWI; 16 (12.4%) had significant MRA lesions, of which 11 (8.5%) were on proximal vessels. Nine patients had early recurrence (TIA, 7; minor stroke, 2). Only patients with proximal MRA lesions were at higher risk of early recurrence independent of the ABCD2 score (adjusted odds ratio, 5.5; 95% confidence interval, 1.1–27.8; P = .04). CONCLUSIONS: Proximal lesions of cerebral arteries seen on MRA were predictive of recurrent stroke/TIA at 7 days. These findings suggest that MRA could be used to improve the selection of patients with TIA at high risk of early recurrent stroke/TIA.

Imagerie des atteintes intracrâniennes au cours des maladies systémiques

Central nervous system (CNS) involvement in systemic disease (SD) is unusual. MRI features of such lesions are unfamiliar to most radiologists. The diagnosis of SD is still based on clinical features and laboratory findings but some characteristic MRI findings exist for each SD: micronodular leptomeningeal enhancement in sarcoidosis, diffuse or focal pachymeningeal involvement in Wegener disease, dentate nuclei and brain stem lesions in Langerhans cell histiocytosis, meningeal masses, dentate nuclei lesions and periarterial infiltration in Erdheim-Chester disease, meningeal masses in Rosai-Dorfman disease, veinular pontic lesions and cerebral vein thrombosis in Behçet, supratentorial microvascular lesions in lupus and antiphospholipid and Gougerot-Sjögren syndrome. In this work, we explain, describe and illustrate the most characteristic MRI findings for each disease.

Proton MR Spectroscopy of Progressive Multifocal Leukoencephalopathy−Immune Reconstitution Inflammatory Syndrome

We read with great interest the article by Bag et al[1][1] entitled “JC Virus Infection of the Brain.” In this work, the authors dedicated a significant section to the inflammatory forms of progressive multifocal leukoencephalopathy (PML), referred to as PML-immune reconstitution inflammatory

Apport de l’IRM de perfusion et de la spectroscopie dans le diagnostic de toxoplasmose cérébrale atypique

We report an atypical case of cerebral toxoplasmosis (CT) in a 70-year-old woman with a history of breast cancer. Contrast-enhanced computed tomography revealed a single ring-enhancing lesion in the pons with perifocal oedema and mass effect. Toxoplasma encephalitis was suggested by means of diffusion weighted imaging, MR perfusion and MR spectroscopy, leading to the discovery of HIV infection. The patient was put on antitoxoplasma therapy. Subsequent clinical and radiological improvements confirmed the diagnosis.