PMC3779388_01
61-year-old male with change in mental status and decline in function diagnosed with semantic dementia. (a and b) The magnetic resonance imaging (MRI) transaxial views of the T1-weighted and (c and d) T2-weighted images with proton density and fluid suppression sequences demonstrate diffuse parenchymal atrophy, slightly more substantial in the temporal lobes (arrows on a and c). These non-specific findings do raise the possibility of frontotemporal dementia (FTD). A thalamic infarct (arrows on b and d), along with subtle white matter abnormalities are also seen, which are suggestive of vascular dementia, though inconsistent with the negative magnetic resonance angiography findings.
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F1
The MRI [Figure 1] demonstrated diffuse parenchymal atrophy, which was slightly more extensive in the temporal lobes.
61-year-old male with change in mental status and decline in function diagn osed with semantic dementia. The fluorine-18 fluorodeoxyglucose (F-18 FDG) positron emission tomography (PET) of the brain was obtained and coregistered with the T1-weighted sequences of the MRI. Two separate triangulated cross-sections of the reconstructed images in (a and d) axial views, (b and e) coronal views, and (c and f) sagittal dimensions show significantly reduced uptake corresponding to atrophy in the temporal lobes (arrows on a), involving the amygdalae (arrows on b), hippocampi (arrows on e), and Wernicke's area (arrow on c). The function is well preserved in the remaining areas of global atrophic change and white matter changes. There is also reduced activity in the location of the suspected right thalamic infract (arrow d). These findings are pathognomonic for semantic dementia.
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F2
The resultant PET/MR images [Figure 2] demonstrated a pattern of decreased FDG uptake that was predominantly confined to the temporal lobes and was particularly severe in the amygdalae and hippocampi.