Brain abscesses: etiologic categorization with in vivo proton MR spectroscopy.
ABSTRACT To compare the metabolite patterns observed at in vivo proton magnetic resonance (MR) spectroscopy of brain abscesses in patients for whom bacteriologic information was obtained from cultures and to categorize the MR spectral patterns with respect to the underlying etiologic agents.
MR imaging and in vivo single-voxel proton MR spectroscopic data obtained from 75 patients with brain abscesses were retrospectively analyzed. Ex vivo spectroscopic experiments with the pus from 45 of these patients also were performed, and the data were further categorized on the basis of bacteriologic information. Quantification of various metabolites and metabolite ratios and statistical analyses of lactate and lactate/amino acid (AA) ratio levels were performed by using one-way analysis of variance.
On the basis of in vivo proton MR spectroscopic and bacteriologic analysis findings, data were classified into three categories: Group 1 data showed resonances of lactate, AAs, and acetate, with or without succinate at proton MR spectroscopy; cultures for this group showed obligate anaerobes or a mixture of obligate and facultative anaerobes. The metabolite patterns in the group 2 and group 3 data were similar to the pattern of the group 1 data, with the exception that acetate and succinate resonances were absent. Culture was positive for either obligate aerobes or facultative anaerobes in group 2 and was sterile in group 3. At analysis of variance, in vivo data showed significant differences in lactate/AA ratios (P =.008), and ex vivo data showed significant differences in lactate levels (P =.001) among the three groups.
It is possible to differentiate anaerobic from aerobic or sterile brain abscesses on the basis of metabolite patterns observed at in vivo proton MR spectroscopy. This information may be useful in facilitating prompt and appropriate treatment of patients with these abscesses.
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ABSTRACT: Nocardia intracranial abscesses occur almost exclusively in patients who are immunocompromised due to diabetes, transplantation, or HIV/AIDS. Patients usually present with seizures, headaches, fevers, and menin-gismus. Laboratory evaluation is nonspecific but may reveal an elevated erythrocyte sedimentation rate and white blood cell count. An important task in the workup of intracranial infection is searching for local causes such as sinusitis, otitis media, or mastoiditis.Proceedings (Baylor University. Medical Center) 10/2012; 25(4):381-2.
Article: Neuroimaging of infections.[show abstract] [hide abstract]
ABSTRACT: Neuroimaging plays a crucial role in the diagnosis and therapeutic decision making in infectious diseases of the nervous system. The review summarizes imaging findings and recent advances in the diagnosis of pyogenic brain abscess, ventriculitis, viral disease including exotic and emergent viruses, and opportunistic disease. For each condition, the ensuing therapeutic steps are presented. In cases of uncomplicated meningitis, cranial computed tomography (CT) appears to be sufficient for clinical management to exclude acute brain edema, hydrocephalus, and pathology of the base of skull. Magnetic resonance imaging (MRI) is superior in depicting complications like sub-/epidural empyema and vasculitic complications notably on FLAIR (fluid-attenuated inversion recovery)-weighted images. The newer technique of diffusion-weighted imaging (DWI) shows early parenchymal complications of meningitis earlier and with more clarity and is of help in differentiation of pyogenic abscess (PA) from ring enhancing lesions of other etiology. Proton magnetic resonance spectroscopy (PMRS) seems to produce specific peak patterns in cases of abscess. The presence of lactate cytosolic amino acids and absence of choline seems to indicate PA. Also in cases of suspected opportunistic infection due to toxoplasma DWI may be of help in the differentiation from lymphoma, showing no restriction of water diffusion. In patients with herpes simplex and more exotic viruses like West Nile and Murray Valley virus DWI allows earlier lesion detection and therapeutic intervention with virustatic drugs.NeuroRx 05/2005; 2(2):324-32.