Amyloid Imaging Update: How the Amyloid Landscape Is Changing in Light of the Recent Food and Drug Administration Approval of Antiamyloid Therapeutics

Use of off-table head holder. (A) Canthomeatal line should be vertical and perpendicular to imaging table. (B) Even small deflections of canthomeatal line from vertical position can result in abnormal head tilt. (Reprinted from (22).)

Patient positioning. (A) Body strap, knee cushion, and blanket applied for patient comfort. (B) Chin strap, head strap, and laser lights applied to position and secure head. Long arrow indicates laser light at level of patient’s ear, assisting in fixing table at proper height. Short arrow indicates laser light centered on patient’s head to keep it straight. (Courtesy of Barbara Grabher and Virtua Health System, Vorhees, NJ.)

Examples of patient motion on static (A–C) and dynamic (D and E) images. (D) No motion. (E) Patient motion indicated by arrows. (F) Gold standard of motion-free negative (left) and positive images (right). Yellow arrows in A and B indicate thick scalp. Red arrow in C illustrates that tracer uptake does not reach the scalp. Blue arrow in C shows activity shifts (bright/dark) on same structure. Yellow arrows in F indicate scalp, and blue arrow indicates skull and cerebral spinal fluid. (A–C and F courtesy of Life Molecular Imaging; D and E reprinted from (23).)

Normal and abnormal distribution patterns of uptake of ¹⁸F-florbetapir (A and B), ¹⁸F-flutemetamol (C–E), and ¹⁸F-florbetaben (G and H). Normal patterns of tracer uptake are similar where you can differentiate white matter from gray matter. In abnormal pattern of tracer uptake, you cannot differentiate white matter from gray matter. (F) Assessment of striatal binding, as required by FDA for Vizamyl only. White arrows denote level of transverse slice. Yellow dashed lines and arrowheads in G and H denote areas taken directly from florbetaben package insert. Cerebellum: contrast between white matter (arrows) and gray matter is seen in both negative and positive scans. Extracerebral tracer uptake in scalp and in posterior sagittal sinus (arrowhead) can be seen. Lateral temporal lobes: Spiculated or “mountainous” appearance of white matter (arrows) is seen in negative scan, and radioactive signal does not reach outer rim of brain (dashed line) because of lower tracer uptake in gray matter. Positive scan shows “plumped”, smooth appearance of outer border of brain parenchyma (dashed line) due to tracer uptake in gray matter. Frontal lobes: Spiculated appearance of white matter in frontal lobes (arrows) is seen in negative scan. Positive scan shows that tracer uptake in these regions has “plumped”, smooth appearance due to increased gray matter signal (dashed line). Posterior cingulate/precuneus: Adjacent and posterior to splenium (arrow), these regions appear as hypointense “hole” (circle) in negative scan, whereas this hole is “filled-up” (circle) in positive scan. Parietal lobes: In negative scan, midline between parietal lobes can be easily identified (long arrow); white matter has spiculated appearance (short arrow) with low signal near outer rim of brain (dashed line). In positive scan, midline between parietal lobes is much thinner. Cortical areas are “filled-up” and are smooth in appearance as tracer uptake extends to outer rim of brain. f = frontal; lt = lateral temporal; s = striatal region; pc = posterior cingulate region; cc = callosum; p = pons; ip = inferior parietal. (A and B reprinted from (1), C–E reprinted from (2), F reprinted with permission of (24), and G and H reprinted from (3).)

AQ steps. (1) Coregistration of PET and MR images. (2) Segmentation of MR image. (3) Voxel-to-voxel intersection of segmented MR to predefined atlas to obtain individual regions of interest. (4) Application of individual regions of interest onto coregistered PET image and extraction of regional values. (Reprinted with permission of (7).)

(A) How SUV and SUVRs are calculated for particular brain regions. (B) Defined reference regions and 7 defined target regions. (A courtesy of Life Molecular Imaging Medical Affairs; B reprinted with permission of (9).)