Fabiano Reis

Neuroimaging in Pineal Tumors

Background and Purpose. The authors report radiological findings in 11 tumors in the pineal region, which were histologically diagnosed as germinomas, pineocytomas pineoblastomas, ependymomas, teratomas, and astrocytomas. Methods. Computed tomography (CT) was performed in seven patients and magnetic resonance imaging (MRI) was performed in all patients. Results. CT showed a solid or solid/cystic mass with variable contrast enhancement. MRI showed a heterogeneous mass, with hypointense signal on T1 and iso/hyperintense signal on T2‐weighted images (WI) and gadolinium enhancement. Extension to adjacent structures occurred in five patients and spread through the cerebral spinal fluid (CSF) in two. Conclusions. Pineal region tumors have no pathognomonic imaging pattern. MRI and CT are complementary in diagnosis and are important to determine localization, extension, and meningeal spread.

Focal transient lesion in the splenium of the corpus callosum in three non-epileptic patients.

IntroductionWe analyzed the imaging features of transient focal lesions in the splenium of the corpus callosum (SCC) in non-epileptic patients receiving antiepileptic drugs (AEDs).MethodsWe identified signal abnormalities in the SCC in three non-epileptic patients, all of them receiving AEDs. We examined two of these patients with multiplanar magnetic resonance (MR) imaging using 1.0-T equipment including fluid-attenuated inversion recovery (FLAIR), T2-weighted (TSE) and T1-weighted (SE) sequences before and after injection of contrast agent. The third patient was studied using 1.5-T equipment with the same sequences. Additionally, a T1 SE sequence with a magnetization transfer contrast pulse off resonance (T1 SE/MTC), diffusion-weighted imaging (EPI-DWI) and apparent diffusion coefficient (ADC) maps were obtained.ResultsWe observed an identical pattern of imaging abnormalities in all patients characterized by round lesions, hyperintense on FLAIR and hypointense on T1 SE images, located in the central portion of the SCC. One lesion showed homogeneous gadolinium enhancement and perilesional vasogenic edema. This particular lesion showed restricted diffusion confirmed on the ADC map. This pattern was considered consistent with focal demyelination. Follow-up MR examinations showed complete disappearance or a clear reduction in lesion size. All patients had been treated with AEDs, but they did not show any clinical signs of toxicity, interhemispheric symptoms, or abnormal neurological findings (including seizures).ConclusionWe believe that our MR findings might be interpreted as transient lesions related to AED toxicity. They presumably resulted from focal demyelination in the central portion of the SCC.

Pleomorphic xanthoastrocytoma: magnetic resonance imaging findings in a series of cases with histopathological confirmation

Pleomorphic xanthoastrocytoma (PXA) is a rare glioma. This paper aimed to analyze magnetic resonance imaging (MRI) characteristics in a series of patients diagnosed with PXA. We analyzed MRI findings in 9 patients with histopathologic diagnosis of PXA in our department over the last 12 years. The mean age of patients was 27.3 years. Cortical location was observed in all cases. The lesion imaging was solid-cystic in six cases. In eight cases, the solid component presented hypo or isointense on T1 and iso or hyperintense on T2. Contrast enhancement in the solid component was observed in eight cases. The observed imaging pattern of PXA was superficial location with leptomeningeal involvement, solid-cystic pattern and contrast enhancement in the solid component. We should consider that the association between PXA and other cortical tumors may occur, particularly, with gangliogliomas, which tend to be the main differential diagnosis in MRI.

MRI findings in the diagnosis and monitoring of Rasmussen's encephalitis.

Rasmussens encephalitis is a devastating syndrome of multifocal brain dysfunction and focal seizures. Magnetic resonance (MR) findings, associated with clinical data and electroencephalogram (EEG), may indicate the diagnosis and could be an indicative of prognosis. We studied 5 patients with Rasmussens encephalitis, assessing clinical history and MR images. All patients had refractory focal seizures with a predominant motor component associated with hemispheric atrophy, that was proportional to severity of disease and neurological deficits in these patients. Gray and white matter abnormal signal on T2 MR images were found in patients who had hemiparesis. It was not related to the duration of the disease but to aggressiveness. MR proton spectroscopy in severe disease showed lactate and choline increase and decreased NAA, reflecting neuronal and axonal loss, gliosis and elevated membrane turnover and recent - crisis (not controlled). MR studies, in addition to help in diagnosis, may be useful for monitoring metabolic changes and progression of disease in Rasmussens encephalitis.

Neuroparacoccidioidomycosis (NPCM): Magnetic Resonance Imaging (MRI) Findings

ObjectiveTo describe the magnetic resonance imaging (MRI) patterns of the central nervous system (CNS) involvement by neuroparacoccidioidomycosis (NPCM).MethodsBetween January 1999 and March 2011, a review of MRI data analysis from 8 cases of NPCM was performed. The following MRI characteristics were examined by an experienced neuroradiologist: topography of lesions, aspects on T1- and T2-weighted images (WI), contrast enhancement, diffusion and spectroscopy.ResultsAll patients had evidence of paracoccidioidomycosis infection outside the nervous system. Regarding CNS involvement, five patients had only supratentorial lesions; three had infra- and supratentorial ones. Meningeal extension occurred in three patients. The lesions were predominantly hyperintense on T1WI. At T2WI, a hypointense component was present in five cases as well as a perilesional abnormal white matter. A ring-enhancement pattern was seen in five cases. Spectroscopy was performed in three patients and showed an increased lipid peak in all of them. In one case, there was also an increased choline peak.ConclusionNPCM is rare, and MRI may help its differentiation from other inflammatory lesions. However, the presence of active infection outside CNS and some imaging characteristics should point to this diagnosis.

Linfoma do sistema nervoso central: ensaio iconográfico

Ilustramos este ensaio iconografico de linfoma do sistema nervoso central com imagens de ressonância magnetica obtidas em nosso servico nos ultimos 13 anos e discutimos algumas das principais caracteristicas radiologicas deste tipo de linfoma, primario e secundario. O linfoma sistema nervoso central e um tumor relativamente infrequente, mas alguns achados na ressonância magnetica podem sugerir este diagnostico.

The pattern of proton magnetic resonance spectroscopy in non-neoplastic encephalic lesions.

The purpose of this article is show the role of proton magnetic resonance spectroscopy (MRS), associated with magnetic resonance images, in the study of non-neoplastic disorders, helping in diagnosis and better characterization of the nature of the lesion. Herein, we analyzed single voxel proton spectroscopy in eight different non-neoplastic lesions, displayed in six categories (infectious, ischaemic, demyelinating, inflammatory, malformation of development and phacomatosis). The presence or the ratios of signal intensities brain tissue metabolites observed with this technique (N-acetyl aspartate, choline, creatine, lactate and lipids) helped in their differentiation with neoplastic lesions and helped in correct diagnosis. In infectious diseases, signals of acetate, succinate and amino acids were also important. In conclusion, proton MRS is a noninvasive method, very useful as an additional technique to define the nature of non-neoplastic encephalic lesions.

Analysis of neoplastic lesions in magnetic resonance imaging using self-organizing maps

OBJECTIVE To provide an improved method for the identification and analysis of brain tumors in MRI scans using a semi-automated computational approach, that has the potential to provide a more objective, precise and quantitatively rigorous analysis, compared to human visual analysis. BACKGROUND Self-Organizing Maps (SOM) is an unsupervised, exploratory data analysis tool, which can automatically domain an image into selfsimilar regions or clusters, based on measures of similarity. It can be used to perform image-domain of brain tissue on MR images, without prior knowledge. DESIGN/METHODS We used SOM to analyze T1, T2 and FLAIR acquisitions from two MRI machines in our service from 14 patients with brain tumors confirmed by biopsies--three lymphomas, six glioblastomas, one meningioma, one ganglioglioma, two oligoastrocytomas and one astrocytoma. The SOM software was used to analyze the data from the three image acquisitions from each patient and generated a self-organized map for each containing 25 clusters. RESULTS Damaged tissue was separated from the normal tissue using the SOM technique. Furthermore, in some cases it allowed to separate different areas from within the tumor--like edema/peritumoral infiltration and necrosis. In lesions with less precise boundaries in FLAIR, the estimated damaged tissue area in the resulting map appears bigger. CONCLUSIONS Our results showed that SOM has the potential to be a powerful MR imaging analysis technique for the assessment of brain tumors.

Visual pathway abnormalities were found in most multiple sclerosis patients despite history of previous optic neuritis

OBJECTIVE It was to investigate visual field (VF) abnormalities in a group of multiple sclerosis (MS) patients in the remission phase and the presence of magnetic resonance imaging (MRI) lesions in the optic radiations. METHODS VF was assessed in 60 participants (age range 20-51 years): 35 relapsing-remitting MS patients [20 optic neuritis (+), 15 optic neuritis (-)] and 25 controls. MRI (3-Tesla) was obtained in all patients. RESULTS Visual parameters were abnormal in MS patients as compared to controls. The majority of VF defects were diffuse. All patients except one had posterior visual pathways lesions. No significant difference in lesion number, length and distribution was noted between patients with and without history of optic neuritis. One patient presented homonymous hemianopsia. CONCLUSION Posterior visual pathway abnormalities were found in most MS patients despite history of previous optic neuritis.

Central nervous system lymphoma: magnetic resonance imaging features at presentation

OBJECTIVE This paper aimed at studying presentations of the central nervous system (CNS) lymphoma using structural images obtained by magnetic resonance imaging (MRI). METHODS The MRI features at presentation of 15 patients diagnosed with CNS lymphoma in a university hospital, between January 1999 and March 2011, were analyzed by frequency and cross tabulation. RESULTS All patients had supratentorial lesions; and four had infra- and supratentorial lesions. The signal intensity on T1 and T2 weighted images was predominantly hypo- or isointense. In the T2 weighted images, single lesions were associated with a hypointense signal component. Six patients presented necrosis, all of them showed perilesional abnormal white matter, nine had meningeal involvement, and five had subependymal spread. Subependymal spread and meningeal involvement tended to occur in younger patients. CONCLUSION Presentations of lymphoma are very pleomorphic, but some of them should point to this diagnostic possibility.