RESUMO
Superparamagnetic iron oxide was applied as a reticuloendothelial contrast agent in the diagnosis of cirrhosis and hepatitis in seven patients. Three patients had compensated cirrhosis, and four had active hepatitis. T1- and T2-weighted spin-echo magnetic resonance images were obtained before and 1 hour after the administration of iron oxide. Eight patients without diffuse liver disease served as a control group. Normal liver tissue showed a 75% +/- 9% reduction in signal intensity after the administration of iron oxide, and the liver appeared homogeneously hypointense. Cirrhotic liver tissue showed a smaller response (P less than .05) to iron oxide, with a 52% +/- 13% reduction in liver signal intensity. Inhomogeneous structures could be observed in enhanced images and are thought to represent fibrous bands or regenerating nodules. Liver tissue with active hepatitis showed a markedly reduced response to iron oxide (11% +/- 2%) (P less than .05), and the parenchyma appeared homogeneous. The authors conclude that the uptake of iron oxide particles is inhomogeneously altered in cirrhosis because of structural changes and homogeneously decreased in hepatitis because of functional changes of hepatic parenchyma.
Assuntos
Hepatite/diagnóstico , Ferro , Cirrose Hepática/diagnóstico , Imageamento por Ressonância Magnética/métodos , Óxidos , Meios de Contraste , Óxido Ferroso-Férrico , Humanos , Projetos Piloto , Estudos ProspectivosRESUMO
We reviewed the MR findings in 56 patients with neurocysticercosis (NCC). MR findings were correlated with other neuroradiologic findings in 40 cases, with histopathologic studies in 15 surgically treated patients, and with autopsy findings in one case. Active NCC was characterized by the presence of a cyst in the brain parenchyma (53%) or in an intraventricular subependymal (22%) or subarachnoid (10%) location. The cysticercus appeared as a vesicle with a high-intensity signal nodule that corresponded to the scolex. Cyst mobility was observed in two intraventricular cases. Periventricular edema and ependymitis appeared as high-intensity signal on T2 sequences. Inactive NCC (15%) was characterized by calcifications (signal void on T1 and T2 sequences), aqueductal stenosis, and tissue thickness in the basal meninges. Degenerative cysticercus appeared on MR as an irregular vesicle without a scolex. Active NCC was better detected with MR than with CT (85% vs 21%), whereas inactive forms were observed better with CT (23% vs 14%). We conclude that MR is sensitive in the diagnosis of active NCC and may be useful in evaluating the degenerative changes in the parasite that occur as a result of natural degeneration, host response, or medical therapy.
Assuntos
Encefalopatias/patologia , Cisticercose/patologia , Imageamento por Ressonância Magnética , Adolescente , Adulto , Idoso , Anti-Helmínticos/uso terapêutico , Encefalopatias/líquido cefalorraquidiano , Encefalopatias/diagnóstico por imagem , Criança , Cisticercose/líquido cefalorraquidiano , Cisticercose/diagnóstico por imagem , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Valores de Referência , Espaço Subaracnóideo/diagnóstico por imagem , Espaço Subaracnóideo/patologia , Tomografia Computadorizada por Raios XRESUMO
PURPOSE: Autopsy studies have shown that pregnancy results in physiologic pituitary enlargement. We used magnetic resonance imaging (MRI) to corroborate those findings in vivo. PATIENTS AND METHODS: Based on gestational age, 32 normal primigravid patients were divided into three groups: Group I (n = 10), less than 12 gestational weeks; Group II (n = 11), 13 to 26 gestational weeks; and Group III (n = 11), 27 gestational weeks or more. The pituitary dimensions and volumes in these groups were compared with those in 20 healthy nulliparous women (control group). RESULTS: MRI measurements showed a significant increase in pituitary volume in Groups I, II, and III when compared with the control group (p less than 0.001). Furthermore, there was an increase in pituitary volume between Groups I and II and between Groups II and III, although the former was not statistically significant (p greater than 0.05). At the end of pregnancy, the hypophysis had increased 2.6 mm in vertical, anteroposterior, and transversal dimensions, with an overall increase of 136 percent when compared with that of the control group. CONCLUSION: Baseline measurements of the normal enlargement of the pituitary gland that occurs during pregnancy could prove useful when evaluating pregnant patients with suspected pituitary tumors or lymphocytic hypophysitis.
Assuntos
Imageamento por Ressonância Magnética , Hipófise/anatomia & histologia , Gravidez/fisiologia , Adolescente , Adulto , Feminino , Humanos , Hipófise/crescimento & desenvolvimentoRESUMO
Magnetic resonance images were obtained before and after treatment in 17 patients with 29 amebic liver abscesses. Pretreatment T1-weighted images showed a sharply circumscribed, heterogeneous, low-signal-intensity mass, devoid of normal hepatic tissue and corresponding to the abscess cavity as measured sonographically. T2-weighted images showed the abscess cavity as a hyperintense region and also showed a larger region of hyperintensity extending from the cavity margins to the liver surface, corresponding to edematous but morphologically normal liver tissue. After treatment, the abscess cavity became homogeneously hypointense on T1-weighted images, corresponding to liquefaction of the abscess center. With successful treatment, concentric rings corresponding to (a) an inner margin of inflamed granulation tissue, (b) bands of type I collagen, and (c) the outer margin of atrophic and/or mildly inflamed liver tissue became prominent on T1- and T2-weighted images. T2-weighted images showed rapid resolution of the perifocal hepatic edema.