Current uses of intracranial vessel wall imaging for clinical practice: a high-resolution MR technique recently available.

Intracranial vessel wall imaging plays an increasing role in diagnosing intracranial vascular diseases. With the growing demand and subsequent increased use of this technique in clinical practice, radiologists and neurologists should be aware of the choices in imaging parameters and how they affect image quality, clinical indications, methods of assessment, and limitations in the interpretation of these images. Due to the improvement of the MRI techniques, the possibility of accurate and direct evaluation of the abnormalities in the arterial vascular wall (vessel wall imaging) has evolved, adding substantial data to diagnosis when compared to the indirect evaluation based on conventional flow analyses. Herein, the authors proposed a comprehensive approach of this technique reinforcing appropriated clinical settings to better use intracranial vessel wall imaging.

Current uses of intracranial vessel wall imaging for clinical practice: a high-resolution MR technique recently available / Usos atuais do estudo de parede vascular intracraniana na prática clínica: uma técnica de RM de alta resolução recentemente disponível

ABSTRACT Intracranial vessel wall imaging plays an increasing role in diagnosing intracranial vascular diseases. With the growing demand and subsequent increased use of this technique in clinical practice, radiologists and neurologists should be aware of the choices in imaging parameters and how they affect image quality, clinical indications, methods of assessment, and limitations in the interpretation of these images. Due to the improvement of the MRI techniques, the possibility of accurate and direct evaluation of the abnormalities in the arterial vascular wall (vessel wall imaging) has evolved, adding substantial data to diagnosis when compared to the indirect evaluation based on conventional flow analyses. Herein, the authors proposed a comprehensive approach of this technique reinforcing appropriated clinical settings to better use intracranial vessel wall imaging.

RESUMO O estudo angiográfico intracraniano não invasivo está sendo amplamente utilizado no diagnóstico de doenças vasculares intracranianas. Com a crescente demanda e o aumento subsequente do uso dessa técnica na prática clínica, radiologistas e neurologistas devem estar cientes das opções nos parâmetros de imagem e como estes afetam a qualidade da imagem, as indicações clínicas, os métodos de avaliação e as limitações na interpretação dessas imagens. Devido ao aprimoramento das técnicas de imagem por RM, a possibilidade de avaliação precisa e direta das anormalidades na parede vascular arterial (vessel wall imaging) evoluiu, agregando dados substanciais ao diagnóstico quando comparados à avaliação indireta baseada em análises de fluxo convencionais. Neste artigo, os autores discorrem sobre a avaliação e interpretação dos achados de imagem desta nova técnica e suas aplicações clínicas.

Uso do tensor de difusão na avaliação dos padrões de acometimento da substância branca em pacientes com tumores cerebrais: é uma ferramenta útil para o diagnóstico diferencial? / Use of diffusion tensor magnetic resonance imaging in the assessment of patterns of white matter involvement in patients with brain tumors: is it useful in the differential diagnosis?

OBJETIVO: Propõe-se avaliar o papel do tensor de difusão na avaliação dos diferentes padrões de acometimento da substância branca em pacientes com tumores cerebrais e a utilidade desta técnica no diagnóstico diferencial dessas neoplasias. MATERIAIS E MÉTODOS: Quarenta e quatro pacientes com tumores cerebrais, incluindo gliomas de baixo grau, astrocitomas anaplásicos, glioblastomas multiformes e metástases, foram estudados com imagens de ressonância magnética convencional e tensor de difusão. Os tratos de substância branca próximos aos tumores foram caracterizados como deslocados, interrompidos, infiltrados e edematosos. RESULTADOS: Houve significativa sobreposição entre os padrões de acometimento da substância branca pelo tensor de difusão, uma vez que o padrão deslocado foi observado em todos os tipos de tumor. Os padrões interrompido e infiltrado foram encontrados em glioblastomas multiformes e astrocitomas anaplásicos e o padrão edematoso foi observado em metástases. CONCLUSÃO: Os padrões de envolvimento dos tratos de substância branca cerebral avaliados pelo tensor de difusão auxiliam no mapeamento dos tratos adjacentes aos tumores e fornecem informações importantes sobre a extensão do tumor, no entanto, eles não possibilitam fazer a distinção entre gliomas de baixo e alto graus e metástases.

OBJECTIVE: The present study was aimed at evaluating the role of diffusion tensor imaging for the assessment of different patterns of white matter involvement in patients with brain tumors and the utility of this technique for differential diagnosis of such neoplasms. MATERIALS AND METHODS: Forty-four patients with brain tumors, including low-grade gliomas, anaplastic astrocytomas, glioblastomas multiforme and metastases, were studied with conventional and diffusion tensor magnetic resonance imaging. White matter tracts around the tumors were characterized as displaced, disrupted, infiltrated and edematous. RESULTS: A significant overlap was observed between patterns of white matter involvement on diffusion tensor images as the displaced pattern was seen in all the types of tumor. Disrupted and infiltrated patterns were found in glioblastomas multiforme and anaplastic astrocytomas. The edematous pattern was found in the cases of metastases. CONCLUSION: Diffusion tensor imaging patterns of white matter involvement assists in the mapping of tracts adjacent to tumors, providing significant data about tumors extent; however, they cannot distinguish low-grade and high-grade gliomas from metastases.

Confiabilidade da análise qualitativa da ressonância magnética do encéfalo em prematuros extremos / Reliability of qualitative assessment of brain magnetic resonance imaging in extremely premature infants

OBJETIVO: O objetivo deste estudo foi avaliar a confiabilidade da análise visual qualitativa dos achados de imagem de ressonância magnética (RM) em recém-nascidos prematuros extremos. MATERIAIS E MÉTODOS: Uma coorte de 45 recém-nascidos de idade gestacional de 30 semanas ou menos foram inseridos neste estudo. Dois neurorradiologistas, cegos quanto aos dados clínicos, avaliaram de forma independente as RMs de crânio em relação aos seguintes achados: presença de hipersinal difuso e excessivo (DEHSI), dilatação dos ventrículos laterais, hemorragia intracraniana, áreas de sinal anormal em núcleos da base e córtex, áreas de aspecto cístico, deformidades ventriculares, dilatação do espaço subaracnóideo, leucoencefalomalácia precoce e anormalidades corticais. RESULTADOS: Quarenta e um pacientes (91,1 por cento) apresentaram exame de RM anormal. Os achados mais comuns foram DEHSI (75,6 por cento) e dilatação dos ventrículos (42,2 por cento). A concordância interobservadores entre os dois experientes neurorradiologistas foi alta (κ > 0,60) para a maioria das alterações detectadas pela RM. O valor de kappa foi moderado (κ = 0,52) para alargamento do espaço subaracnoide e fraco (κ = 0,39) para DEHSI na substância branca. CONCLUSÃO: A avaliação qualitativa da maioria dos achados de imagem por RM de neonatos prematuros extremos foi considerada confiável, entretanto, a presença de DEHSI na substância branca demonstrou um grau de confiabilidade menor.

OBJECTIVE: The present study was aimed at evaluating the reliability of the qualitative visual assessment of brain abnormalities using conventional brain MRI in extremely preterm infants. MATERIALS AND METHODS: A cohort of 45 consecutive infants with gestational age of 30 weeks or less (median of 27 weeks, ranging from 25 to 30 weeks) was enrolled in this study. Two independent, experienced neuroradiologists blindly reviewed MRI studies of the infants' brain for diffuse and excessive high-signal intensity (DEHSI), dilated lateral ventricles, intracranial hemorrhage, areas of abnormal signal in the basal ganglia and cortex, cyst-like areas, ventricular deformities, enlargement of subarachnoid spaces, early leukoencephalomalacia, and cortical abnormalities. RESULTS: Forty-one patients (91.1 percent) presented abnormalities at MRI. The most common findings were DEHSI in the white matter (75.6 percent) and ventricular dilatation (42.2 percent). The interobserver agreement was high (κ > 0.60) for most of the abnormal MRI findings. The kappa statistic values were moderate for enlargement of the subarachnoid space (κ = 0.52) and was only low for DEHSI in the white matter (κ = 0.39). CONCLUSION: Conventional MRI seems to be a reliable method for evaluating the most common brain abnormalities in extremely premature infants; however, the presence of DEHSI in the white matter demonstrated to be is a less reliable finding.

Proton magnetic resonance spectroscopy in children with fetal alcohol spectrum disorders / Espectroscopia por ressonância magnética de prótons em crianças com transtornos do espectro alcoólico fetal

OBJECTIVE: To analyze the metabolic constitution of brain areas through proton magnetic resonance spectroscopy in children affected with fetal alcohol spectrum disorder compared with normal children. METHOD: The sample of this case-control study included eight boys with epidemiologic history of in utero exposure to alcohol (median age 13.6±3.8 years) who were diagnosed with fetal alcohol spectrum disorder, and eight controls (median age 12.1±3,4 years). An 8 cm³ single voxel approach was used, with echo time 30 ms, repetition time 1500 ms, and 128 acquisitions in a 1.5T scanner, and four brain areas were analyzed: anterior cingulate, left frontal lobe, left striatum, and left cerebellar hemisphere. Peaks and ratios of metabolites N-acetylaspartate, choline, creatine, and myo-inositol were measured. RESULTS: Children with fetal alcohol spectrum disorder showed a decrease in choline/creatine ratio (p=0.020) in left striatum and an increase in myo-inositol/creatine ratio (p=0.048) in left cerebellum compared with controls. There was no statistically significant difference in all peaks and ratios from the anterior cingulate and frontal lobe between the two groups. CONCLUSION: This study found evidence that the left striatum and left cerebellum are affected by intrauterine exposure to alcohol. Additional studies with larger samples are necessary to expand our knowledge of the effects of fetal exposure to alcohol.

OBJETIVO: Analisar a composição metabólica de áreas encefálicas através da espectroscopia de prótons por ressonância magnética em crianças com transtornos do espectro alcoólico fetal e crianças normais. MÉTODO: A amostra deste estudo de casos-controles incluiu 8 meninos com história epidemiológica de exposição fetal ao álcool (idade mediana 13,6±3,8 anos), diagnosticados com transtorno do espectro alcoólico fetal, e 8 controles (idade mediana 12,1±3,4 anos). Utilizou-se voxel único de 8 cm³, tempo de eco 30 ms, tempo de repetição 1.500 ms, 128 aquisições, em scanner de 1,5T para as seguintes áreas: cíngulo anterior, lobo frontal esquerdo, estriado esquerdo e hemisfério cerebelar esquerdo. Estudaram-se os picos e as razões dos metabólitos N-acetilaspartato, colina, creatina e o mio-inositol. RESULTADOS: As crianças acometidas apresentaram diminuição da razão colina/creatina (p=0,020) no estriado esquerdo, e aumento da razão mio-inositol/creatina (p=0,048) no cerebelo esquerdo. Não houve diferença estatisticamente significativa nos valores encontrados no cíngulo anterior e lobo frontal entre os dois grupos. CONCLUSÃO: Este estudo encontrou evidências de que o estriado e o cerebelo esquerdos são acometidos pela exposição intra-uterina ao álcool. Estudos adicionais com amostras maiores são essenciais para expandir nosso conhecimento dos efeitos da exposição fetal ao álcool.

Evaluation of white matter in patients with multiple sclerosis through diffusion tensor magnetic resonance imaging

OBJECTIVE: To study the white matter of patients with multiple sclerosis (MS) with diffusion tensor magnetic resonance (MR) imaging (DTI). METHOD: Forty patients with clinical-laboratorial diagnosis of relapsing-remitting MS and 40 age- and sex-matched controls, who underwent conventional and functional (DTI) MR imaging, were included in the study. The DTI sequences resulted in maps of fractional anisotropy (FA) and regions of interest were placed on the plaques, peri-plaque regions, normal-appearing white matter (NAWM) around the plaques, contralateral normal white matter (CNWM) and normal white matter of the controls (WMC). The FA values were compared and the statistical treatment was performed with the Mann-Whitney U test. RESULTS: The mean FA in plaques was 0.268, in peri-plaque regions 0.365, in NAWM 0.509, in CNWM 0.552 and in WMC 0.573. Statistical significant differences in FA values were observed in plaques, peri-plaque regions and in NAWM around the plaques when compared to the white matter in the control group. There was no significant difference between the FA values of the CNWM of patients with MS and normal white matter of controls. CONCLUSION: Patients with MS show difference in the FA values of the plaques, peri-plaques and NAWM around the plaques when compared to the normal white matter of controls. As a result, DTI may be considered more efficient than conventional MR imaging for the study of patients with MS.

OBJETIVO: Estudar a substância branca de pacientes com esclerose múltipla (EM) através de imagens de ressonância magnética (RM) por tensor de difusão (DTI). MÉTODO: Foram avaliados 40 pacientes com diagnóstico clínico-laboratorial de EM remitente-recorrente e quarenta controles pareados por idade e sexo, os quais foram submetidos à RM convencional e funcional (DTI). As seqüências de DTI resultaram em mapas de anisotropia fracionada (FA) e as regiões de interesse foram posicionadas nas placas, regiões peri-placas, substância branca aparentemente normal (SBAN) ao redor das placas, substância branca normal contra-lateral (SBNC) e substância branca normal do grupo controle (SBC). Os valores de FA foram comparados e a análise estatística foi realizada utilizando o teste Mann-Whitney U. RESULTADOS: A média de FA nas placas foi 0,268, nas regiões peri-placas 0,365, na SBAN 0,509, na SBNC 0,552 e na SBC 0,573. Foram observadas diferenças estatisticamente significativas nos valores de FA nas placas, regiões peri-placas e na SBAN ao redor das placas quando comparados com a SBC. Não houve diferença entre os valores de FA na SBNC dos pacientes com EM e na SBC. CONCLUSÃO: Pacientes com EM demonstram diferença nos valores de FA nas placas, peri-placas e SBAN ao redor das placas quando comparados com a SBC. Assim, o DTI pode ser considerado mais eficiente do que as seqüências de ressonância magnética convencional no estudo dos pacientes com EM.

Central pontine and extrapontine myelinolysis: report of a case with a tragic outcome.

OBJECTIVE: To report a pediatric case of central pontine and extrapontine myelinolysis, a rare neurological disease often associated with rapid correction of hyponatremia. DESCRIPTION: A 15 year-old female adolescent developed locked-in syndrome during severe hyponatremia. Brain magnetic resonance imaging was consistent with the diagnosis of central pontine and extrapontine myelinolysis. COMMENTS: Serum sodium correction should proceed slowly and cautiously, based upon a careful calculation of sodium deficit, in order to minimize metabolic stress and avoid the occurrence of this dreadful complication, which has a tragic outcome in most cases. There is no scientifically proved effective treatment for myelinolysis, and severe cases usually have a dismal prognosis.

Central pontine and extrapontine myelinolysis: report of a case with a tragic outcome

OBJECTIVE: To report a pediatric case of central pontine and extrapontine myelinolysis, a rare neurological disease often associated with rapid correction of hyponatremia.DESCRIPTION: A 15 year-old female adolescent developed locked-in syndrome during severe hyponatremia. Brain magnetic resonance imaging was consistent with the diagnosis of central pontine and extrapontine myelinolysis.COMMENTS: Serum sodium correction should proceed slowly and cautiously, based upon a careful calculation of sodium deficit, in order to minimize metabolic stress and avoid the occurrence of this dreadful complication, which has a tragic outcome in most cases. There is no scientifically proved effective treatment for myelinolysis, and severe cases usually have a dismal prognosis.