title: The usefulness of fully three-dimensional OSEM algorithm on lymph node metastases from lung cancer with 18F-FDG PET/CT.
abstract: OBJECTIVE
  This work assessed the usefulness of fully three-dimensional ordered subset expectation maximization (3D-OSEM) algorithm for lymph node (LN) metastases from lung cancer. 3D-OSEM images were evaluated by comparing them with those reconstructed by conventional algorithms, such as conventional OSEM algorithm (2D-OSEM) for 2D acquisition and Fourier rebinning plus conventional OSEM algorithm (FORE + OSEM) for 3D acquisition.
  
  
  METHODS
  In a phantom study, the contrast ratio, the image noise and the signal-to-noise ratio (SNR) were calculated, and the detectability and the image quality of these images were visually evaluated. In a clinical study, 14 patients suffering from lung cancer with LN metastases were evaluated. The image quality and the malignancy, and the detectability were visually evaluated.
  
  
  RESULTS
  The contrast ratio was significantly improved using 3D-OSEM as compared with FORE + OSEM, and it was similar to 2D-OSEM. The image noise and SNR in 3D-OSEM images were significantly improved compared with those by other algorithms (p < 0.001). In the visual assessment, the image quality was significantly improved in 3D-OSEM images compared with those by 2D-OSEM and FORE + OSEM (p < 0.001, p = 0.001, respectively). In the clinical study, the image quality and the detectability of LN metastases were improved in 3D-OSEM images compared with those by FORE + OSEM (p < 0.001, p = 0.006, respectively), and image quality and detectability were similar to those of 2D-OSEM images.
  
  
  CONCLUSIONS
  3D-OSEM algorithm successfully improved the diagnostic accuracy of LN metastases in 3D-PET tests.
authors.affiliation: Functional Imaging Division, Research Center for Innovative Oncology, National Cancer Center Hospital East, Kashiwa, Japan.
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Inoue
authors.forename: Etsuo
authors.initials: E
authors.lastname: Moriya
authors.forename: Takayuki
authors.initials: T
authors.lastname: Suzuki
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Ohnuki
authors.forename: Takashi
authors.initials: T
authors.lastname: Sato
authors.forename: Hideaki
authors.initials: H
authors.lastname: Kitamura
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Sasaki
authors.forename: Masahiro
authors.initials: M
authors.lastname: Fukushi
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Moriyama
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Fujii
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D021621:Imaging, Three-Dimensional; D008175:Lung Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology*; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D019047:Phantoms, Imaging; D049268:Positron-Emission Tomography; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed
chemical_list: D019788:Fluorodeoxyglucose F18