Fig. 5

Named signs of normal and abnormal patterns of amyloid activity on florbetapir PET/CT. Normal activity in the white matter of the frontal lobes leads to the “tree-in-winter sign” on coronal images, abnormal activity in the gray matter leads to the appearance of leaves known as the “tree-in-summer sign” (a, b). Absence of gray matter activity in the medial orbitofrontal lobes creates a diamond pattern of the white matter activity which is lost in abnormal studies (c, d). A similar phenomenon is seen at the cerebral convexities where the superior white matter tracts create the “double convex lens sign” (e) which is lost with abnormal gray matter activity morphing to the “kissing hemispheres sign” (f). Lastly, normal absence of gray matter activity in the temporal and occipital lobes creates a mountainous façade referred to as the “temporo-occipital ridge” (g), whereas abnormal gray matter activity leads to a more flat profile termed the “temporo-occipital plain” (h)