Neuropathological correlate of the “concentric target sign” in MRI of HIV-associated cerebral toxoplasmosis
Department of Neuropathology, National Institute of Mental Health & Neurosciences, Bangalore, India. . Journal of Magnetic Resonance Imaging
(Impact Factor: 3.21).
08/2013; 38(2). DOI: 10.1002/jmri.24036
Cerebral toxoplasmosis is a frequent cause of focal brain lesions in the setting of immunodeficiency states, particularly acquired immune deficiency syndrome (AIDS), and magnetic resonance imaging (MRI) is an important diagnostic modality to differentiate toxoplasmosis from tuberculoma, and primary central nervous system lymphoma with diverse therapeutic implications. Several imaging patterns have been described in cerebral toxoplasmosis. The "concentric target sign" is a recently described MRI sign on T2-weighted imaging of cerebral toxoplasmosis that has concentric alternating zones of hypo- and hyperintensities. It is believed to be more specific than the well-known "eccentric target sign" in the diagnosis of cerebral toxoplasmosis and hence more useful in differentiation from other focal brain lesions in the context of AIDS. The concentric target sign, seen in deep parenchymal lesions, is distinct from the surface-based cortical "eccentric" target sign. The histopathological correlate of the latter has been recently described, but that of the concentric target sign is not known. In this study we describe the neuropathological correlate of this concentric target sign from the postmortem of a 40-year-old man with AIDS-associated cerebral toxoplasmosis. The concentric alternating zones of hypo/hyper/iso/intensities corresponded to zones of hemorrhage/fibrin-rich necrosis with edema/coagulative compact necrosis/inflammation with foamy histiocytes admixed with hemorrhage forming the outermost zone, respectively. The exclusive specificity of this sign in cerebral toxoplasmosis remains to be further elucidated. J. Magn. Reson. Imaging 2013;. © 2013 Wiley Periodicals, Inc.
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ABSTRACT: The aim of this paper is to illustrate the potential of magnetic resonance imaging (MRI) in diagnosis, differential diagnosis, treatment planning and evaluation of therapy effectiveness of pyogenic brain abscesses, through the use of morphological (or conventional) and functional (or advanced) sequences. Conventional MRI study is useful for the identification of lesions, to determine the location and morphology and allows a correct hypothesis of nature in the most typical cases. However, the differential diagnosis from other brain lesions, such as non-pyogenic abscesses or necrotic tumors (high-grade gliomas and metastases) is often only possible through the use of functional sequences, as the measurement of diffusion with apparent diffusion coefficient (DWI-ADC), proton magnetic resonance spectroscopy ((1)H-MRS) and perfusion weighted imaging (PWI), which complement the morphological sequences and provide essential information on structural, metabolic and hemodynamic characteristics allowing greater neuroradiological confidence. Modern diagnostic MRI of pyogenic brain abscesses cannot be separated from knowledge, integration and proper use of the morphological and functional sequences.
Journal of Neuroradiology 06/2014; 41(3). DOI:10.1016/j.neurad.2014.05.004 · 1.75 Impact Factor
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ABSTRACT: Neurologic disease in acquired immunodeficiency syndrome (AIDS) patients is related either to opportunistic pathogens or to direct central nervous system (CNS) invasion by the human immunodeficiency virus. Despite the increasing availability of antiretroviral therapy, opportunistic infections continue to afflict patients in the developing world and in other populations with limited access to appropriate treatment. Classic CNS infections in the setting of AIDS include toxoplasmosis, cryptococcosis, progressive multifocal leukoencephalopathy, and cytomegalovirus encephalitis. Additionally, AIDS patients are far more susceptible to acquiring CNS tuberculosis and neurosyphilis, both of which exhibit altered disease characteristics in the setting of immunosuppression. Neuroimaging is a crucial component of the diagnostic work-up of these conditions, and findings include, but are not limited to, intracranial mass lesions, white matter disease, meningoencephalitis, vascular complications, and hydrocephalus. Though various disease processes can produce imaging findings that overlap with one another, certain characteristic patterns may suggest a particular pathogen, and advanced imaging techniques and laboratory tests allow for definitive diagnosis. Knowledge of the imaging patterns seen in the setting of AIDS-related CNS disease is vital to the neuroradiologist, whose interpretation may guide decisions related to treatment and further work-up.
Topics in magnetic resonance imaging: TMRI 10/2014; 23(5):275-291. DOI:10.1097/RMR.0000000000000031
Available from: jstage.jst.go.jp
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ABSTRACT: Cerebral toxoplasmosis is a rare disease predominantly found in immunocompromised hosts. However, cerebral toxoplasmosis has not been frequently described in association with the use of immunosuppressive medications. We herein report a case of cerebral toxoplasmosis in a 76-year-old Caucasian woman on methotrexate and infliximab for rheumatoid arthritis. The patient presented with right facial droop, slurred speech and difficulty walking. In addition to receiving methotrexate and infliximab and owning a cat, she had no other obvious risk factors. Imaging studies were not conclusive; however, brain biopsy confirmed the diagnosis. Serology was positive for anti-toxoplasma immunoglobulin G. Cerebral toxoplasmosis should be included in the differential diagnosis of patients under immunosuppressive medication who present with neurological manifestations.
Internal Medicine 06/2015; 54(11):1433-6. DOI:10.2169/internalmedicine.54.3977 · 0.90 Impact Factor
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