Assuntos
Síndrome de Beckwith-Wiedemann/complicações , Programas de Rastreamento , Neoplasias do Mediastino/etiologia , Neuroblastoma/etiologia , Alberta , Síndrome de Beckwith-Wiedemann/genética , Pré-Escolar , Feminino , Humanos , Neoplasias do Mediastino/genética , Neoplasias do Mediastino/prevenção & controle , Neuroblastoma/genética , Neuroblastoma/prevenção & controleRESUMO
PURPOSE: To investigate the decrease in signal intensity on T1 - weighted MR images of some hemorrhagic intracranial lesions after administration of contrast material. METHODS: Postprocessing digital image subtraction was performed in 16 MR studies (13 patients) of lesions that showed hyperintensity on noncontrast T1-weighted images. Repetition time and echo time were identical for all precontrast and postcontrast studies. Regions of interest were measured in each lesion, contralateral white matter, and background (before and after contrast enhancement). RESULTS: In six of 16 MR studies, a significant net decrease in signal intensity was seen within the hemorrhagic lesion after contrast enhancement (reverse enhancement). All the lesions were hematomas within residual or recurrent malignant tumors. CONCLUSIONS: Digital image subtraction confirms the existence of reverse enhancement. This phenomenon is due to the combined T2-shortening effects of two paramagnetic substances, methemoglobin and gadolinium, which cause the signal reduction produced by the T2 effects to occur at lower concentrations of gadolinium.
Assuntos
Neoplasias Encefálicas/diagnóstico , Hemorragia Cerebral/diagnóstico , Meios de Contraste , Compostos Heterocíclicos , Imageamento por Ressonância Magnética/métodos , Meglumina , Recidiva Local de Neoplasia/diagnóstico , Neoplasia Residual/diagnóstico , Compostos Organometálicos , Ácido Pentético/análogos & derivados , Técnica de Subtração , Adolescente , Adulto , Idoso , Criança , Combinação de Medicamentos , Feminino , Gadolínio , Gadolínio DTPA , Humanos , Processamento de Imagem Assistida por Computador , Masculino , Metemoglobina/metabolismo , Pessoa de Meia-Idade , Sensibilidade e Especificidade , SoftwareRESUMO
We report the MR and CT findings with pathologic correlation in a case of severe methanol intoxication. There was bilateral hemorrhagic necrosis of the putamen and caudate nuclei and, in addition, extensive subcortical necrosis and symmetric bilateral necrosis of the pontine tegmentum and optic nerves, which may indicate poor prognosis.
