Journal of neuroimaging : official journal of the American Society of Neuroimaging
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The relationship between subcortical hyperintensity (SH) on magnetic resonance imaging (MRI), cortical perfusion on single photon emission computed tomography (SPECT), and cognitive function is not well understood. The authors examined these relationships in individuals with vascular dementia (VaD), paying particular attention to frontal lobe function to determine whether the presence of SH on MRI was associated with frontal hypoperfusion on SPECT, which in turn would be associated with impairments of executive-attention function. ⋯ These results suggest that a functional "disconnection" between the frontal lobes and subcortical structures does not fully account for the magnitude of global cognitive impairment in VaD. Cortical perfusion as measured by SPECT appears to be associated with cognitive performance, but not specifically executive-attention dysfunction. Additional studies are needed to further examine the relationship between subcortical and cortical function in VaD.
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High-resolution magnetic resonance images obtained in a patient several months after carbon monoxide (CO) intoxication revealed nearly symmetric regional atrophy of both lateral temporal lobes. This pattern of cortical lesions after CO exposure has not been reported before. The patient suffered from severe cognitive deficits including a transient Klüver-Bucy-like behavior. This report underlines the value of high-resolution magnetic resonance imaging in chronic stages of CO intoxication in the attempt to understand the neuroanatomical bases of the observed behavior.
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Case Reports
Cerebral vasculitis: diagnosis and follow-up with transcranial Doppler ultrasonography.
The authors report a patient with postpartum intracerebral hemorrhage associated with cerebral vasculitis. Cerebral circulation was assessed with transcranial Doppler (TCD) ultrasonography, magnetic resonance angiography, and conventional cerebral angiography. Initial TCD studies demonstrated bilateral patchy increased cerebral blood flow velocity (CBFV) in the anterior circulation with complete normalization during remission. This case report provides evidence that cerebral vasculitis leads to relevant CBFV changes and that the TCD technique may assist in diagnosis and follow-up of these patients.
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A 36-year-old homosexual man with 6 months of visual symptoms and headaches had right homonymous hemianopia, mild new learning impairment, and alexia with agraphia. The initial brain magnetic resonance imaging (MRI) scan was reported consistent with left occipital infarction. Subsequent MRI demonstrated abnormal demyelination in subcortical white matter and deep parieto-occipital white matter bilaterally, but primarily left. ⋯ After the antiretroviral regimen was intensified by the addition of a protease inhibitor, rapid clinical and radiographic improvement occurred with subsequent MRI studies revealing only residual left parieto-occipital encephalomalacia. PML in AIDS patients has been associated with a nearly uniformly poor prognosis until recent reports of improved outcomes after highly active antiretroviral therapy. This patient with PML and AIDS similarly showed a robust clinical and MRI response to intensive antiretroviral combination therapy, which has been maintained for more than 3 years.
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Case Reports
Does reversal of ischemia on diffusion-weighted imaging reflect higher apparent diffusion coefficient values?
This study investigated whether ischemia on diffusion-weighted imaging (DWI) that reverses has higher apparent diffusion coefficients (ADCs). A patient treated with thrombolytics was evaluated with serial magnetic resonance imaging studies before treatment, at 3 and 14 days and at 4 weeks. ⋯ The mean ADC was 7.43 x 10(-3) mm2/s in the 6 regions that reversed and 7.31 x 10(-3) mm2/s in the 6 regions that persisted (P < .036). With thrombolytic treatment, large ischemic lesions on DWI may reverse, and these areas display higher mean ADCs.