MRI features of intra-axial histiocytic brain mass lesions.

AIM: To describe MRI features, including diffusion-weighted imaging (DWI), magnetic resonance spectroscopy (MRS), and perfusion-weighted imaging (PWI), of intra-axial tumour-like presentations of four different subtypes of histiocytosis. MATERIAL AND METHODS: The brain MRI findings of 23 patients with histologically proven histiocytosis were reviewed retrospectively (11 Langerhans cell histiocytosis [LCH], eight Erdheim-Chester disease [ECD], one overlap form LCH/ECD, two Rosai-Dorfman disease [RDD], and one haemophagocytic lymphohistiocytosis [HLH]) with single or multiple enhancing intraparenchymal brain lesions. RESULTS: Histiocytic brain mass lesions show some similar MRI features including Supra and/or infratentorial and/or paraventricular subcortical well-delineated masses, linear ependymal enhancement along the ventricles and brain stem lesions. Masses always present with mixed hyper- and hypointense signal on T2-weighted imaging (WI). Their enhancement is often homogeneous. Apparent diffusion coefficient (ADC) values are often normal or elevated. CONCLUSION: The presence of multiple periventricular and subcortical enhancing lesions with mixed signal intensity on T2WI and normal or high ADC values should lead radiologists to consider the diagnosis of histiocytic lesions and search for associated systemic lesions.

Malignant primary diffuse leptomeningeal gliomatosis with histone H3.3 K27M mutation.

INTRODUCTION: Malignant primary diffuse leptomeningeal gliomatosis (MPDLG) are rare central nervous system neoplasms associated with a poor outcome. CASE REPORT: We report the case of a 40-year-old woman who presented with unusual worsening of bilateral sciatica, headaches, diplopia and a left proptosis. MRI of the head and spine showed multiple leptomeningeal lesions with no intra parenchymal involvement. The search for a primary tumor was negative. An open surgical biopsy of the prominent intradural lumbar tumor was performed within a week. Histopathology, immunochemistry and molecular analyses revealed a malignant glioma with histone H3.3 K27M mutation. The patient was referred to the neuro-oncologist for chemotherapy and craniospinal radiotherapy. Despite aggressive therapy, she died of disseminated tumoral progression, 18 weeks after the diagnosis. CONCLUSION: MPLG is a rare tumor which should be considered whenever a patient presents with diffuse or multinodular meningeal contrast-enhancing lesions. Some cases of MLPG share histological and immunophenotypical features with diffuse midline gliomas H3-K27M-mutant, a rapidly fatal disease. The diagnosis remains histopathological and, therefore a biopsy is obligatory without delay. Immunohistochemistry and/or molecular analyses are now currently essential for a formal classification and, to provide a better prediction of clinical outcome, particularly in this heterogeneous group of tumors.

Endocrine Manifestations in a Monocentric Cohort of 64 Patients With Erdheim-Chester Disease.

CONTEXT: Erdheim-Chester disease (ECD) is a rare non-Langerhans cell histiocytosis, characterized by infiltration of foamy histiocytes in multiple organs. Endocrine involvement has mostly been described in case reports. OBJECTIVE: We performed systematic endocrine evaluation in a large cohort of patients with ECD. DESIGN: This was a single-center observational study conducted between October 2007 and May 2013. SETTING: The evaluation was conducted in Pitié-Salpêtrière Hospital (Paris, France), a tertiary care hospital. PATIENTS: Sixty-four consecutive patients with ECD (sex ratio, 3.6; mean age, 57.6 years [range, 20-80 years]). Thirty-six patients had follow-up assessments. INTERVENTIONS: There were no interventions. MAIN OUTCOME MEASURES: Clinical, biological, and morphological evaluations of pituitary, gonadal, adrenal, and thyroid functions, as well as metabolic evaluation, were performed. RESULTS: Diabetes insipidus was found in 33.3% of patients, frequently as the first manifestation of ECD. Anterior pituitary dysfunction was found in 91.3% of patients with full anterior pituitary evaluation, including somatotropic deficiency (78.6%), hyperprolactinemia (44.1%), gonadotropic deficiency (22.2%), thyrotropic deficiency (9.5%), and corticotropic deficiency (3.1%). Thirty-five patients (54.7%) had ≥2 anterior pituitary dysfunctional axes, rising to 69.6% (16 of 23) when only patients with complete evaluations were considered. Two patients had panhypopituitarism. Infiltration of the pituitary and stalk was found with magnetic resonance imaging in 24.4% of patients. Testicular insufficiency was found in 53.1% of patients, with sonographic testicular infiltration in 29% of men, mostly bilateral. Computed tomography adrenal infiltration was found in 39.1% of patients, and 1 case of adrenal insufficiency was observed. No patient was free of endocrine hormonal or morphological involvement. Endocrine dysfunctions were most often permanent, and new deficits appeared during follow-up. CONCLUSION: Endocrine involvement is very frequent in ECD and should be evaluated carefully at diagnosis and during follow-up.

Cerebral tumor or pseudotumor?

Pseudotumoral lesions are uncommon but important to identity lesions. They can occur during inflammatory diseases (systemic diseases, vasculitis, demyelinating diseases), infectious, and vascular diseases. Also, in a patient with a treated tumor, pseudo-progression and radionecrosis must be differentiated from the tumoral development. Diagnosis can be difficult on an MRI scan, but some MRI aspects in conventional sequences, diffusion, perfusion and spectroscopy can suggest the pseudotumoral origin of a lesion. Imaging must be interpreted according to the context, the clinic and the biology. The presence of associated intracranial lesions can orientate towards a systemic or infectious disease. A T2 hyposignal lesion suggests granulomatosis or histiocytosis, especially if a meningeal or hypothalamic-pituitary involvement is associated. Non-tumoral lesions are generally not hyperperfused. In the absence of a definitive diagnosis, the evolution of these lesions, whether under treatment or spontaneous, is fundamental.

[Erdheim-Chester disease]. / Maladie d'Erdheim-Chester.

Erdheim-Chester disease is a rare and orphan disease. Despite having been overlooked previously, numerous new cases have been diagnosed more recently. The number of Erdheim-Chester disease cases reported has increased substantially: more than 300 new cases have been published in the past 10 years. This situation is mainly a result of the generally better awareness among pathologists, radiologists, and clinicians of various aspects of this rare disease. The field has been particularly active in the last few years, with evidence of the efficacy of interferon-α, the description of a systemic pro-inflammatory cytokine signature, and most recently, reports of the dramatic efficacy of BRAF inhibition in severe, BRAF(V600E) mutation-associated cases of Erdheim-Chester disease. Also, BRAF mutations have been found in more than half of the patients with Erdheim-Chester disease who were tested. Detailed elucidation of the pathogenesis of the disease is likely to lead to the development of better targeted and more effective therapies.

Long-term white matter changes after severe traumatic brain injury: a 5-year prospective cohort.

BACKGROUND AND PURPOSE: Extensive white matter damage has been documented in patients with severe traumatic brain injury, yet how this damage evolves in the long term is not well understood. We used DTI to study white matter changes at 5 years after traumatic brain injury. MATERIALS AND METHODS: There were 8 healthy control participants and 13 patients with severe traumatic brain injury who were enrolled in a prospective observational study, which included clinical assessment and brain MR imaging in the acute setting (< 6 weeks) and 2 years and 5 years after injury. Only subjects with mild to moderate disability or no disability at 1 year were included in this analysis. DTI parameters were measured in 20 different brain regions and were normalized to values obtained in an age-matched control group. RESULTS: In the acute setting, fractional anisotropy was significantly lower in the genu and body of the corpus callosum and in the bilateral corona radiata in patients compared with control participants, whereas radial diffusivity was significantly (P < .05) higher in these tracts. At 2 years, fractional anisotropy in these tracts had further decreased and radial diffusivity had increased. No significant changes were detected between 2 and 5 years after injury. The baseline radial diffusivity and fractional anisotropy values in the anterior aspect of the brain stem, genu and body of the corpus callosum, and the right and left corona radiata were significantly (P < .05) associated with neurocognitive sequelae (including amnesia, aphasia, and dyspraxia) at year 5. CONCLUSIONS: DTI changes in major white matter tracts persist up to 5 years after severe traumatic brain injury and are most pronounced in the corpus callosum and corona radiata. Limited structural change is noted in the interval between 2 and 5 years.

[Neurological manifestations of Behçet's disease]. / Manifestations neurologiques de la maladie de Behçet.

Neurological manifestations of Behçet's disease (BD) occur in 5.3 to more than 50% of patients. They are divided into two major forms: "parenchymal" lesions, which include mainly meningoencephalitis as opposed to "extra-parenchymal" lesions (i.e. cerebral venous thrombosis and arterial aneurysms). Myelitis or peripheral neuropathy is exceptional. The neuro-Behçet syndrome (NBS) should be considered in the setting of neurological manifestations, particularly headache and pyramidal signs, in a young man diagnosed with BD. However, its recognition may be difficult when neurological manifestations are the presenting features of BD (one third of cases), and requires a thorough knowledge of clinical manifestations and morphological lesions. Thus, parenchymal NB lesions classically exhibit inflammatory characteristics on MRI and are located at the meso-diencephalic junction and in the brainstem, rarely with a supratentorial extension. Meningitis is not systematically associated, and may be absent in about 30% of cases. The pathogenesis of these lesions is incompletely understood, but inflammatory infiltrates include mainly neutrophils and activated T cells (mainly Th17). Differential diagnoses include infectious diseases (herpes, listeria, tuberculosis), and inflammatory diseases (i.e. multiple sclerosis and sarcoidosis). A prompt recognition of NBS should lead to initiate adequate therapies in order to limit the risk of sequelae, relapses or death.

Imaging findings of intraventricular and ependymal lesions.

Intraventricular and ependymal lesions comprise a wide spectrum of tumoral, cystic, vascular, infectious and inflammatory disorders. With respect to tumoral and cystic diseases, the location, age and CT and MRI patterns are the main factors for diagnosis. The MRI findings of infectious diseases are supported by the clinical history, immune status and laboratory findings. Intracranial associated lesions may be very helpful for the diagnosis of Sturge-Weber, subependymal giant cell astrocytoma and systemic diseases, such as sarcoidosis and histiocytosis. Intraventricular vascular lesions are rare but present typical features on neuroimaging. The aim of this review is to provide a detailed description of these disorders with an emphasis on the key imaging findings and to generate a narrow differential diagnosis. We present a diagnostic approach based on the solid or cystic aspect of the intraventricular focal mass, its origin from the ventricular wall or choroid plexus and its location within the ventricular system. We also propose a differential diagnosis for ependymal dissemination: the ependymal enhancement may be due to ventriculitis from adjacent parenchymal lesions, the ependymal spread of tumors or infectious or inflammatory/systemic diseases.

[Central nervous system involvement in systemic diseases: Spectrum of MRI findings]. / 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.

Diffusion-weighted MRI in acute stroke within the first 6 hours: 1.5 or 3.0 Tesla?

OBJECTIVES: To compare the sensitivity and specificity of 1.5-T and 3.0-T diffusion-weighted MRI (DWI) to detect hyperacute ischemic stroke lesions. METHODS: We blindly reviewed the DWI of 135 acute stroke patients and 34 controls performed at 1.5 T (n = 108) or 3.0 T (n = 61). The stroke patients all had subsequently proved carotid territory ischemic stroke and were imaged within the first 6 hours after stroke onset. Four readers (2 neuroradiologists and 2 stroke neurologists) blinded to clinical data and magnetic field strength recorded the presence of ischemic lesions on DWI and apparent diffusion coefficient (ADC) maps if necessary. Sensitivity, specificity, and false-negative rates were computed. Signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and DWI contrasts were calculated at both field strengths. RESULTS: The accuracy of DWI in stroke diagnosis was superior at 1.5 T (98.8%) than at 3.0 T (90.9%, p = 0.03). The sensitivity decreased from 99.1% at 1.5 T to 92.5% at 3.0 T (p = 0.06) and the specificity from 97.8% to 84.1% (p = 0.002). ADC map readings did not improve accuracy, sensitivity, or specificity. The false-negative rate was 0.6% at 1.5 T and 6.1% at 3.0 T. Type of readers, stroke severity, and type of the coil did not affect diagnosis value. SNR and CNR were significantly higher at 3 T (p < 0.0001) but DWI contrast was lower (p = 0.04). CONCLUSIONS: Blind reading by 4 experts of a large series of images shows that 1.5-T diffusion-weighted MRI (DWI) is better than 3.0-T DWI for the imaging of hyperacute stroke during the therapeutic window of thrombolysis.

Reliability of the ECASS radiological classification of postthrombolysis brain haemorrhage: a comparison of CT and three MRI sequences.

BACKGROUND: Postthrombolysis brain haemorrhagic transformations (HT) are often categorized with the CT-based classification of the European Cooperative Acute Stroke Study (ECASS). However, little is known about the reliability of this classification and its extension to MRI. Our objective was to compare the inter- and intraobserver reliability of this classification on CT and 3 MRI sequences. METHODS: Forty-three patients with postthrombolysis HT on CT or at least 1 of the 3 MRI sequences: fluid-attenuation inversion recovery (FLAIR), diffusion-weighted imaging (DWI), and T2* gradient recalled echo (T2*GRE) were selected. Twelve control patients without any bleeding were added to avoid a bias based on a pure HT-positive cohort. Each series of images were independently classified with the ECASS method by 6 blinded observers. Inter- and intraobserver reproducibility was categorized from poor to excellent depending on kappa values. RESULTS: The inter- and intraobserver overall concordance of the classification was good for T2*GRE, DWI and CT (kappa > 0.6) and moderate for FLAIR (kappa < 0.6). The interobserver concordance for parenchymal haematomas was excellent for T2*GRE (kappa > 0.8) and moderate for CT, FLAIR and DWI. CONCLUSION: The T2*GRE sequence is the most reproducible method to categorize postthrombolysis HT and has an excellent reliability for the severe parenchymal haematoma category, suggesting that this sequence should be used to assess HT in thrombolytic therapy trials.