title: Evaluation of scatter limitation correction: a new method of correcting photopenic artifacts caused by patient motion during whole-body PET/CT imaging.
abstract: OBJECTIVE
  Overcorrection of scatter caused by patient motion during whole-body PET/computed tomography (CT) imaging can induce the appearance of photopenic artifacts in the PET images. The present study aimed to quantify the accuracy of scatter limitation correction (SLC) for eliminating photopenic artifacts.
  
  
  METHODS
  This study analyzed photopenic artifacts in (18)F-fluorodeoxyglucose ((18)F-FDG) PET/CT images acquired from 12 patients and from a National Electrical Manufacturers Association phantom with two peripheral plastic bottles that simulated the human body and arms, respectively. The phantom comprised a sphere (diameter, 10 or 37 mm) containing fluorine-18 solutions with target-to-background ratios of 2, 4, and 8. The plastic bottles were moved 10 cm posteriorly between CT and PET acquisitions. All PET data were reconstructed using model-based scatter correction (SC), no scatter correction (NSC), and SLC, and the presence or absence of artifacts on the PET images was visually evaluated. The SC and SLC images were also semiquantitatively evaluated using standardized uptake values (SUVs).
  
  
  RESULTS
  Photopenic artifacts were not recognizable in any NSC and SLC image from all 12 patients in the clinical study. The SUVmax of mismatched SLC PET/CT images were almost equal to those of matched SC and SLC PET/CT images. Applying NSC and SLC substantially eliminated the photopenic artifacts on SC PET images in the phantom study. SLC improved the activity concentration of the sphere for all target-to-background ratios. The highest %errors of the 10 and 37-mm spheres were 93.3 and 58.3%, respectively, for mismatched SC, and 73.2 and 22.0%, respectively, for mismatched SLC.
  
  
  CONCLUSIONS
  Photopenic artifacts caused by SC error induced by CT and PET image misalignment were corrected using SLC, indicating that this method is useful and practical for clinical qualitative and quantitative PET/CT assessment.
authors.affiliation: aDepartment of Health Sciences, Division of Medical Quantum Science, Faculty of Medical Sciences, Kyushu University, Fukuoka bDepartment of Nuclear Medicine, Cancer Institute Hospital of Japanese Foundation for Cancer Research cResearch Team for Neuroimaging, Tokyo Metropolitan Institute of Gerontology, Tokyo dDepartment of Radiology, Chiba University Hospital, Chiba Prefecture, Japan.
authors.forename: Kenta
authors.initials: K
authors.lastname: Miwa
authors.forename: Takuro
authors.initials: T
authors.lastname: Umeda
authors.forename: Taisuke
authors.initials: T
authors.lastname: Murata
authors.forename: Kei
authors.initials: K
authors.lastname: Wagatsuma
authors.forename: Noriaki
authors.initials: N
authors.lastname: Miyaji
authors.forename: Takashi
authors.initials: T
authors.lastname: Terauchi
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Koizumi
authors.forename: Masayuki
authors.initials: M
authors.lastname: Sasaki
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016477:Artifacts; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009068:Movement; D064847:Multimodal Imaging; D019047:Phantoms, Imaging; D049268:Positron-Emission Tomography; D012189:Retrospective Studies; D012542:Scattering, Radiation; D014057:Tomography, X-Ray Computed; D051598:Whole Body Imaging
chemical_list: D019788:Fluorodeoxyglucose F18