Magnetic resonance imaging of brain abscess with hemorrhage: implications for the mechanism of hemorrhage.
ABSTRACT A 68-year-old woman presented with an extremely rare brain abscess associated with old and acute hemorrhages manifesting as gradual onset of symptoms of headache and fever. Magnetic resonance imaging clearly visualized the hemorrhage as heterogeneously hyperintense on diffusion-weighted imaging, concentric hypo-isointense on T(1)-weighted imaging, and homogeneously hyperintense with a hypointense rim on T(2)(*)-weighted imaging. T(1)-weighted imaging with contrast medium revealed a well-enhanced cyst wall. In spite of treatment with antibiotics, the neurological status of the patient deteriorated due to expansion of the abscess and perifocal edema. Needle aspiration of the cyst yielded bloody purulent fluid. The magnetic resonance imaging findings indicate that neovascularization of the cyst wall is involved in the mechanism of hemorrhage in brain abscess. Careful follow-up examinations are recommended in patients with brain abscess to detect warning signs of neurological deterioration.
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ABSTRACT: Diagnostic difficulties in discriminating brain abscess from necrotic or cystic tumors using conventional CT and MRI have been reported. In this article, we examine the diagnostic ability of diffusion-weighted imaging to discriminate brain abscess from necrotic or cystic tumors. In previous reports, necrotic or cystic tumors show low signal intensity in diffusion-weighted imaging, indicating a high apparent diffusion coefficient (ADC). In contrast, in our study, high signal intensity was observed in the abscess fluid, associated with low ADC.Magnetic Resonance Imaging 02/1996; 14(9):1113-6. · 2.06 Impact Factor
Article: MR imaging of brain abscesses.[show abstract] [hide abstract]
ABSTRACT: The MR images and CT scans of 14 patients with surgically verified pyogenic cerebral abscesses were reviewed. The MR findings correlated well with those seen on CT and were believed to be sufficiently characteristic to allow early and accurate diagnosis with MR alone. These features include (1) peripheral edema producing mild hypointensity on short TR/short TE and marked hyperintensity on long TR/intermediate to long TE scans; (2) central necrosis with abscess fluid hypointense relative to white matter and hyperintense relative to CSF on short TR/short TE scans and hyperintense relative to gray matter on long TR/intermediate to long TE scans (the fluid had concentric zones of varying intensity in seven cases, a finding not previously identified in other lesions); (3) extraparenchymal spread (intraventricular or subarachnoid), which was detected more easily on MR than on CT and was manifested by increased intensity relative to normal CSF on both short TR/short TE and long TR/intermediate TE scans; and (4) visualization of the abscess capsule, which was iso- to mildly hyperintense relative to brain on short TR/short TE scans and iso- to hypointense relative to white matter on long TR/intermediate to long TE scans. On the long TR scans, the relative hypointensity of the rim allowed for visualization of the typical morphologic features of the capsule, which in turn aided in differentiation of abscesses from other lesions (as it does on CT). To investigate the cause of the capsular intensity, pathologic studies of the capsules were reviewed when available (10 cases). Fibrosis was identified in all mature abscess capsules, but the combination of the intensities seen on short TR/short TE and long TR/intermediate to long TE scans as well as the temporal changes in intensity were believed to be incompatible with fibrosis as a cause of the capsular changes. Intensity patterns were suggestive of hemorrhage, but neither acute nor chronic hemorrhage was identified on routine H and E stains, while iron stain revealed scant hemorrhage in only two of the eight patients in whom these stains were used. We believe the capsular intensity (in particular the hypointense rims on long TR scans) may reflect paramagnetic T1, and to a greater extent T2, shortening, possibly due to the presence of heterogeneously distributed free radicals that are products of the respiratory burst produced by actively phagocytosing macrophages in the capsule wall. Distinctive MR features of pyogenic abscesses should afford early and accurate diagnosis.American Journal of Roentgenology 06/1989; 152(5):1073-85. · 2.90 Impact Factor
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ABSTRACT: Hemorrhage into the abscess cavity is a complication of brain abscess. It has been reported to be due to inflammation which results in the damage of the fragile neovasculature of the abscess wall. Hypoxia caused by Fallot's tetralogy or other congenital heart diseases facilitates the damage of these vessels with the lacking supportive tissues, and in turn intracavital bleeding.Pediatric Neurosurgery 02/2006; 42(1):65-6. · 0.42 Impact Factor