Artifacts in brain magnetic resonance imaging due to metallic dental objects.

OBJECTIVE: Artifacts caused by metallic objects, such as dental crowns, dental implants and metallic orthodontic appliances, are a common problem in head and neck MRI. The aim of this retrospective study was to identify the main metal dental objects that produce artifacts on brain MRIs. STUDY DESIGN: Imaged metallic artifacts and their sources were identified. Artifact image plane was rated on a score of 0 or 1 (0--distinguishable for diagnosis and 1--not distinguishable for diagnosis). RESULTS: Seventy-eight percent of the artifacts appearing in images were caused by orthodontic appliances, followed by dental titanium implants (18%) and metallic crowns (4%). Orthodontic appliances obtained the highest scores in all planes. CONCLUSIONS: We concluded that is difficult to avoid the effect of metallic artifacts in the maxillofacial regions on brain scan. Removing metallic parts of the orthodontic appliance should ensure diagnostically useful quality scans.

MRI shows dorsal lesions and spinal cord atrophy in chronic sensory neuronopathies.

BACKGROUND AND PURPOSE: Sensory neuronopathies (SN) represent a specific subgroup of peripheral nervous system diseases, characterized by degeneration of dorsal root ganglia (DRG) and its projections. We tried to estimate the frequency and extent of spinal cord MRI abnormalities in a group of patients with SN and correlate these with clinical and neurophysiological features. METHODS: We performed spinal cord MRI scans in 16 chronic SN patients. Images were analyzed for the presence of posterior hyperintense lesions on T2WI and cord areas at C3 level were obtained using a previously validated method. A group of 14 healthy controls with similar age and gender distribution was used for comparison. ANOVA was employed for statistical analysis. RESULTS: Posterior T2WI lesions were found in 13 out of 16 patients. Cord areas were significantly smaller in SN patients than controls (84.3 x 97.2 mm(2), P < .05). Atrophy correlated with severity of sensory ataxia and neurophysiologic abnormalities but not with duration of disease. CONCLUSIONS: These findings support volumetric spinal cord MRI as a useful tool in the assessment of chronic SN.

Pulmonary involvement in ankylosing spondylitis.

This is a prospective study analyzing 52 asymptomatic, consecutive patients with ankylosing spondylitis (AS), who submitted to a pulmonary investigation that included plain chest radiography, pulmonary function test (PFT), and thoracic high-resolution computed tomography (HRCT). The results were compared according to sex, race, dorsal spine involvement, thoracic diameter, smoking status, and HLA-B27. There were four patients (8%) with an altered plain chest radiograph. PFT presented a restrictive pattern in 52% of the patients. Thoracic HRCT showed abnormalities in 21 patients (40%), predominantly nonspecific linear parenchymal opacities (19%), lymphadenopathy (12%), emphysema (10%), bronchiectasis (8%), and pleural involvement (8%). Linear parenchymal opacities were associated with a smoking history (p=0.026) and dorsal spine involvement (p=0.032). HLA-B27 was not associated with any abnormality. A lower thoracic diameter was observed in patients with dorsal spine involvement (p=0.0001), restrictive pattern at PFT (p=0.023), and linear parenchymal opacities (p=0.015). The study concluded that nonspecific subclinical pulmonary involvement is frequent in AS.

Imaging findings of Ewing's sarcoma in the mandible.

First described by James Ewing in 1921, Ewing's sarcoma (ES) or Ewing's tumor is one of the most aggressive bone tumors known. ES is an uncommon intra-osseous malignant tumor of questionable pathogenesis that occurs in children and young adults. Reports indicate that only 2 to 7% of cases involve the maxillofacial region, usually the mandible ramus, and few reported cases have involved the maxilla. In the present report of a case of ES of the mandible, we describe the results of imaging and evaluation after therapeutic treatment. This report provides a rare opportunity to observe radiologic features of ES in the mandible.

Dissemination patterns of pilocytic astrocytoma.

Two patients with multifocal pilocytic astrocytoma diagnosed by magnetic resonance imaging (MRI) and confirmed by histopathological examination are reported. They presented distinct sites and mechanisms of metastasis: to distant ventricles through the cerebral spinal fluid (CSF) in patient 1 and to contralateral parenchyma, possibly through white matter tracts, in patient 2, a pathway not so far reported in pilocytic astrocytoma. Early detection of multifocal pilocytic astrocytoma by MRI may change treatment strategies and improve prognosis.

Cerebral venous thrombosis: influence of risk factors and imaging findings on prognosis.

PURPOSE: To investigate imaging findings, risk factors and outcome in patients with cerebral venous thrombosis (CVT). METHODS: Records of all patients with diagnosis of CVT between 1992 and 2002 were reviewed. Patients with CNS infection and with CVT secondary to invasive procedures were excluded. Inherited and acquired thrombophilia were searched in all patients. RESULTS: Twenty-four patients (18 women, 6 men) with mean age of 29.5 years (range 3-48 years) were identified. Mean follow-up was 44 months (range 11-145 months). The most common symptoms were headache (75%), vomiting (33%) and impairment of consciousness (21%). Probable causes of CVT could be determined in 21 (88%) patients: pregnancy or puerperium in six (25%), oral contraceptive use in four (17%), head trauma in two (8%), mastoiditis in one (4%), nephrotic syndrome in one (4%), systemic disease in three (13%), and inherited thrombotic risk factors in four (17%) patients. CVT associated with pregnancy, puerperium and use of oral contraceptives had a significant better outcome than CVT caused by inherited thrombophilia or systemic disease (OR=14.4; p=0.02). CT scans were abnormal in 15 (62.5%) patients and MRI with gadolinium was abnormal in all. Those with parenchymal involvement had neurological sequelae during follow-up. All were treated with heparin followed by oral anticoagulants, and none had new or worsening of pre-existing intracerebral hemorrhage. CONCLUSION: MRI is superior to conventional CT for diagnosing CVT. Patients with parenchymal lesions, thrombophilia and antiphospholipid syndrome had greater risk to be left with neurological sequelae. Anticoagulant therapy did not predispose to further intracerebral hemorrhage.

Central neurocytoma: report of two cases.

INTRODUCTION: Central neurocytomas are rare neuroectodermal tumors believed to arise from the subependymal matrix of the lateral ventricles. CASE REPORTS: A 26-year-old woman and a 33-year-old man each had a large, heterogeneous, contrast enhancing mass in the lateral ventricles at the foramen of Monro causing bilateral hydrocephalus. The woman died after surgery, but the man is asymptomatic after three years. HISTOPATHOLOGY: Both tumors were composed of isomorphic rounded cells positive for synaptophysin, chromogranin and NSE, while some reacted for GFAP, vimentin and S-100 protein. Electron microscopy revealed neuropil-like tissue between cells, but synapses were rare.

Crossed cerebellar atrophy in patients with precocious destructive brain insults.

OBJECTIVE: To analyze the frequency and pathogenetic factors of crossed cerebellar atrophy (CCA) in adult patients with epilepsy secondary to destructive brain insults of early development. METHODS: We studied 51 adult patients with epilepsy and precocious destructive lesions. Patients were divided into 3 groups according to the topographic distribution of their lesions on magnetic resonance imaging: group A, hemispheric (n = 9); group B, main arterial territory (n = 25); and group C, arterial border zone (n = 17). We evaluated the presence of CCA visually and with cerebellar volumetric measurement, correlating it with the clinical data. Other features shown on magnetic resonance imaging, such as the thalamus, brainstem, and middle cerebellar peduncle, were also carefully analyzed. RESULTS: Seven patients (13%) had CCA that was associated with the extent of the supratentorial lesion (6 from group A, 1 from group B, and none from group C; P<.001). Status epilepticus was present in 6 patients from group A and in none from the other groups. There was an association between the antecedent of status epilepticus and CCA (P<.001). All patients had atrophy of the cerebral peduncle ipsilateral to the supratentorial lesion and 4 had contralateral atrophy of the middle cerebellar peduncle. The duration of epilepsy was not associated with the presence of CCA (P =.20). CONCLUSIONS: Our data suggest that in patients with epilepsy and destructive insults early in life, the extent of the supratentorial lesion as well as the antecedent of status epilepticus play a major role in the pathogenesis of CCA. Recurrent seizures do not seem to be relevant to the development of CCA.

Proton magnetic resonance spectroscopy and magnetic resonance imaging findings in a patient with central nervous system paracoccidioidomycosis.

The authors describe a patient with brain paracoccidioidomycosis whose magnetic resonance image (MRI) showed multiple hypointense lesions on T2-weighted images with peripheral enhancement after gadolinium injection. Single-voxel proton magnetic resonance spectroscopy (1H-MRS) of one of the lesions showed 2 peaks at 0.9 and 1.32 ppm, corresponding to lipid signals, indicating intense necrosis. The other characteristic peaks of 1H-MRS were undifferentiated from baseline. These findings, although not specific, may help to differentiate fungal abscess from tumoral lesions and other types of abscess.

Early development destructive brain lesions and their relationship to epilepsy and hippocampal damage.

Fifty-one consecutive adult patients with epilepsy and early development destructive brain lesions were divided into three main groups according to the topographic distribution of the lesion on magnetic resonance imaging: hemispheric (H) (n=9); main arterial territory (AT) (n=25) and arterial borderzone (Bdz) (n=17). Eight (89%) patients from group H presented status epilepticus in the first 5 years of life, five of them associated with fever. Seventeen of the 25 patients from group AT (76%) had an obvious hemiparesis observed early in life. In addition, major prenatal events were significantly more common in the group AT compared with the other two groups. Among patients from group Bdz, prenatal or postnatal events were not identified, except for one patient. Conversely, nine patients from group Bdz (60%) showed a history of perinatal complications. Hippocampal atrophy (HA) was determined by visual analysis in 74.5% of all patients and by volumetry in 92%. The frequency of HA was comparable among groups, but patients from group H presented the most severe atrophy and more frequent hyperintense T2 hippocampal signal. In conclusion, these three groups of patients with early destructive lesions and epilepsy (H, AT and Bdz), appear to have distinct pathogenic mechanisms. Our data show that there is a striking association of HA with different patterns of neocortical destructive lesions of early development. This association seems to be related to a common and synchronic pathogenic mechanism. The recognition of the pattern and degree of HA among these patients with intractable seizures may influence the surgical rationale.

Epilepsy and destructive brain insults in early life: a topographical classification on the basis of MRI findings.

Destructive insults of early development can lead to a wide variety of lesional patterns and are a well known cause of epilepsy. The aim of this study is to present a topographic magnetic resonance imaging (MRI) classification of these lesions in adult patients with epilepsy. Thirty-three consecutive patients were divided in three groups according to the topographic distribution of their lesion on MRI: hemispheric (H, n = 7); main arterial territory (AT, n = 18); arterial borderzone (Bdz, n = 8). We analyzed clinical, MRI and magnetic resonance angiography (MRA) data. Status epilepticus (SE) during childhood was more common in group H (7/7) than in the groups AT (1/18) and Bdz (0/8) (P < 0.001). MRA pattern of impaired flow signal in the distal segments of all three major arteries in the affected hemisphere was present in 85.7% of group H patients, and was exclusive to this group. 88.8% (16/18) of patients from group AT presented congenital motor deficit, in contrast to 37.5% (3/8) of group Bdz, and in none of group H (P < 0.001). All patients with Bdz lesions had antecedent of fetal distress, in contrast to 1/7 from group H and 5/18 of group AT (P = 0.001). The MRAs of patients with Bdz lesions were often normal except in those with larger lesions. Our data suggest that in adult patients with epilepsy due to precocious destructive brain insults, a MRI topographical classification distributes them in relatively homogenous clinical groups.

Number and viability of parasite influence seizure frequency in children with neurocysticercosis.

We investigated the relationship between CT findings - number and the viability phase of the parasites - and the seizure frequency in children with neurocysticercosis before and short-term after antiepileptic drug (AED) introduction. We only found a significant interaction between stage of parasitic infection and number of lesions on seizure frequency after AED treatment. Patients with more than five lesions on active or transitional stages had higher seizure frequency predicting a worse short-term prognosis.

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.

Interrelationship between radiologic findings and prognosis of epilepsy in children with neurocysticercosis.

INTRODUCTION: Epileptic manifestations of Neurocysticercosis (NC) appear to depend on number and localization of the cysts. The objective of this study was to investigate the relationship between CT findings, number of parasites and the evolutive stage of the cysts, and the prognosis of epilepsy in children with NC. METHOD: We studied 28 patients with the parenchymal form of NC, considering: epilepsy duration; seizure frequency before and after AED treatment; seizure control; number of AED and recurrence after AED withdrawal. Clinical information was crossed with the number of lesions and disease activity in univariate comparison. RESULTS: The analysis of the clinical data in relation to the number of lesions and disease activity showed no statistical difference among the variables (p>0.05). CONCLUSION: We conclude that the course of epilepsy due to NC in childhood cannot be based exclusively on the number or stage of the parasites.

Angular analysis of corpus callosum in 18 patients with frontonasal dysplasia.

Considering the rarity of the frontonasal dysplasia (FD) and the few reports about it in a large casuistry using magnetic resonance image (MRI), we describe the results of the angular analysis of the corpus callosum of 18 individuals with FD (7 male, 11 female), using an easily-reproductive method. Group I had 12 individuals with isolated form and Group II had 6 individuals with FD syndromic with unknown etiology. The results are presented in set. Comparing with the control group, patients with FD presented alpha angle increase and beta and gamma angles reduction (p<0.05). Alpha and gamma angles express the relationship between the anterior portion of corpus callosum and the floor of 4th ventricle. Considering the embryonary development, these findings would occur secondarily to failure during the development of nasal capsula. Thus, angular anomaly in corpus callosum would be a usual finding, and not fortuitous in patients with FD.

Lateralization of epileptiform discharges in patients with epilepsy and precocious destructive brain insults.

Unilateral destructive brain lesions of early development can result in compensatory thickening of the ipsilateral cranial vault. The aim of this study was to determine the frequency of these bone changes among patients with epilepsy and precocious destructive lesions, and whether a relationship exists between these changes and epileptiform discharges lateralization. Fifty-one patients had their ictal / interictal scalp EEG and skull thickness symmetry on MRI analyzed. Patients were divided into three main groups according to the topographic distribution of the lesion on the MRI: hemispheric (H) (n=9); main arterial territory (AT) (n=25); arterial borderzone (Bdz) (n=17). The EEG background activity was abnormal in 26 patients and were more frequent among patients of group H (p= 0.044). Thickening of the skull was more frequent among patients of group H (p= 0.004). Five patients (9.8%) showed discordant lateralization between epileptiform discharges and structural lesion (four of them with an abnormal background, and only two of them with skull changes). In one of these patients, ictal SPECT provided strong evidence for scalp EEG false lateralization. The findings suggest that compensatory skull thickening in patients with precocious destructive brain insults are more frequent among patients with unilateral and large lesions. However, EEG lateralization discordance among these patients seems to be more related to EEG background abnormalities and extent of cerebral damage than to skull changes.

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.

Brainstem involvement in Sjögren's syndrome-related sensory neuronopathy.

BACKGROUND AND PURPOSE: Sensory neuronopathies (SN) are peripheral nervous system disorders associated with degeneration of dorsal root ganglion neurons. Magnetic resonance imaging (MRI) studies have shown abnormalities limited to T2-weighted high signal intensity in the posterior columns. METHODS AND RESULTS: A 65-year-old woman with Sjögren syndrome had slowly progressive unsteadiness of gait and limb paresthesias. A blink reflex examination suggested a paramedian brainstem lesion, confirmed by MRI. CONCLUSIONS: Sjögren's syndrome-related SN may be associated with a more diffuse immune-mediated aggression, involving also the brainstem, and leading to some of the blink reflex abnormalities observed in nonparaneoplastic SN.

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

Rasmussen's 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 Rasmussen's 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 Rasmussen's encephalitis.

Vascular involvement of the central nervous system and systemic diseases: etiologies and MRI findings.

The objective of this study was to review magnetic resonance imaging (MRI) findings in patients with vascular involvement of the central nervous system (CNS) associated with systemic diseases. We reviewed the MRI findings in clinically suspected cases of vascular involvement of the CNS associated with systemic diseases. Vascular CNS involvement was considered in the presence of characteristic clinical, MRI and/or MR angiography findings. In order to be included in the study, patients needed to have a complete clinical and laboratory investigation and a follow-up of a minimum of 6 months. Twenty-four patients (17 women and 7 men), with mean age of 29.5 years had diagnosis of CNS vasculitis and were included. The clinical presentation was variable, but the most common complaints were headache in 18, focal deficits in 9, disturbances of consciousness in 9, and seizures in 8 patients. Underlying causes for CNS vasculitis were identified in all patients and included systemic lupus erythematosus in eight, tuberculosis in three, bacterial meningitis in three, Takayasu arteritis in two, polyarteritis nodosa in two, syphilis in two, drug abuse in two, yellow fever in one and varicella in one patient. Nonspecific high intensity T2WI/FLAIR lesions in white matter were the most common finding, present in ten patients. Eight patients had infarctions in large cerebral arteries territory, associated or not with high intensity T2WI/FLAIR small foci. Vascular involvement of the CNS can be found in a great variety of systemic diseases, including rheumatologic, infectious and drug abuse. Clinical findings are unspecific and MRI/MRA may help to establish the correct diagnosis.