Figure 1a.
Various causes of cognitive impairment. (a) Coronal T2-weighted MR image in a patient with progressive memory loss shows an extra-axial mass (arrow) with broad-based dural attachment, a finding most compatible with meningioma. Note the marked right frontal vasogenic edema and leftward midline shift with transfalcine herniation. (b) Axial contrast material–enhanced T1-weighted MR image in a patient with a 3-month history of progressive cognitive impairment shows a large left frontal lobe, a solid and cystic heterogeneously enhancing parenchymal mass with rightward midline shift, transfalcine herniation, and left ventricular effacement. This was a case of anaplastic oligodendroglioma. (c) Axial 18F-FDG PET image in a patient with mild cognitive impairment shows markedly decreased uptake in the left temporal lobe (arrow). (d) Corresponding axial CT image in the same patient as in c obtained for attenuation correction shows an acute intraparenchymal hematoma (arrow).