title: Visualization and Quantification of 3-Dimensional Stereotactic Surface Projections for 18F-Flutemetamol PET Using Variable Depth.
abstract: Three-dimensional stereotactic surface projection (3D-SSP) is a widely used method for the analysis of clinical (18)F-FDG brain studies. However, for PET amyloid scans the use of 3D-SSP is challenging because of nonspecific uptake in white matter. Our objective was to implement a method for 3D-SSP quantification and visualization of (18)F-flutemetamol images that avoids extraction of white matter signal.
  
  
  METHODS
  Triangulated brain surface models were extracted from a T1-weighted MR template image. Using an (18)F-flutemetamol-negative template, a maximum depth for each vertex on the surface models was calculated to avoid extraction of white matter. The method was evaluated using (18)F-flutemetamol images from 2 cohorts. Cohort 1 consisted of 105 healthy volunteers and was used to create a normal database for each reference region. Cohort 2 consisted of 171 subjects including patients with Alzheimer disease and mild cognitive impairment and healthy volunteers. Images were spatially normalized using an adaptive template registration method, and SUV ratio 3D-SSP values were computed using the pons and cerebellar cortex as reference regions. Images from cohort 2 were then compared with the normal database and classified into negatives and positives, based on a calculated z score threshold. The results were compared with consensus visual interpretation results from 5 trained interpreters blinded to clinical data.
  
  
  RESULTS
  With the pons as the reference region, the optimal z score threshold was 1.97, resulting in an overall agreement with visual interpretation results in 170 of 171 images (99.42%). With the cerebellar cortex as the reference region, the optimal z score threshold was 2.41, with an overall agreement with visual interpretation in 168 of 171 images (98.25%).
  
  
  CONCLUSIONS
  Variable-depth 3D-SSP allows computation and visualization of (18)F-flutemetamol 3D-SSP maps, with minimized contribution from white matter signal while retaining sensitivity in detecting gray matter signal.
authors.affiliation: GE Healthcare, Uppsala, Sweden Nuclear Medicine and PET, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden; and johan.lilja@radiol.uu.se.
authors.forename: Johan
authors.initials: J
authors.lastname: Lilja
authors.affiliation: GE Healthcare, Uppsala, Sweden Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden.
authors.forename: Lennart
authors.initials: L
authors.lastname: Thurfjell
authors.affiliation: Nuclear Medicine and PET, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden; and.
authors.forename: Jens
authors.initials: J
authors.lastname: Sörensen
mesh_terms: D000544:Alzheimer Disease / Q000000981:diagnostic imaging; D000814:Aniline Compounds; D052160:Benzothiazoles; D001921:Brain / Q000000981:diagnostic imaging; D002525:Cerebellar Cortex / Q000000981:diagnostic imaging; D060825:Cognitive Dysfunction / Q000000981:diagnostic imaging; D015331:Cohort Studies; D066128:Gray Matter / Q000000981:diagnostic imaging; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional; D015588:Observer Variation; D011149:Pons / Q000000981:diagnostic imaging; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals; D013238:Stereotaxic Techniques; D066127:White Matter / Q000000981:diagnostic imaging
chemical_list: D000814:Aniline Compounds; D052160:Benzothiazoles; D019275:Radiopharmaceuticals; C581552:flutemetamol
keywords: Alzheimer’s disease; amyloid; brain mapping; flutemetamol; positron emission tomography; stereotactic surface projections