title: Validation of fast-RAMLA in clinical PET.
abstract: OBJECTIVE
  Images using the fast row action maximum likelihood algorithm (fast-RAMLA), which employs half-interpolated sinograms of conventional 3DRAMLA, are immediately generated following positron emission tomography (PET) scanning and are invariably produced in the process of line-of-response RAMLA (LOR-RAMLA) reconstruction. We quantitatively and visually compared the clinical validity of dual time point [(18)F]-FDG imaging with fast-RAMLA and LOR-RAMLA.
  
  
  METHODS
  An International Electrotechnical Commission (IEC) phantom was established in which the ratio of the activities in the hot sphere was set up and a background of 3.8:1 was scanned and reconstructed using both algorithms. The contrast recovery coefficient was then calculated. The clinical study retrospectively analyzed 35 patients (25 men and 10 women; age range 30-84 years; mean age 63.9 years) with confirmed specific pathological lesions or clinical follow-up; 21 of the patients had 51 malignant lesions and 15 had 23 benign lesions. The maximum standard uptake value (SUV(max)) was measured in all lesions using LOR-RAMLA. The maximal counts of all lesions determined manually were divided by the average count of bilateral ventricles and the aortic arch for standardization on fast-RAMLA, and the values were compared with the SUV(max) of LORRAMLA. Inter-observer variation in detection was determined among three radiologists who blindly reviewed and scored 70 maximum intensity projection images from 35 patients reconstructed using LORRAMLA and fast-RAMLA.
  
  
  RESULTS
  We identified a quantitative correlation and determined the visual quality of lesion detection between fast-RAMLA and LOR-RAMLA and indicated usefulness and improvement point on fast-RAMLA.
  
  
  CONCLUSIONS
  Fast-RAMLA can improve the strategy for using dual time point [(18)F] fluorodeoxyglucose positron emission tomography ([(18)F]-FDG-PET) and increase the efficiency of the [(18)F]-FDG-PET scanner.
authors.affiliation: Department of Radiology, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo 113-0022, Japan. chobidog@nms.ac.jp
authors.forename: Hidetaka
authors.initials: H
authors.lastname: Sato
authors.forename: Keiichi
authors.initials: K
authors.lastname: Cho
authors.forename: Yoshimitsu
authors.initials: Y
authors.lastname: Fukushima
authors.forename: Masato
authors.initials: M
authors.lastname: Shiiba
authors.forename: Kenta
authors.initials: K
authors.lastname: Hakozaki
authors.forename: Tomonari
authors.initials: T
authors.lastname: Kiriyama
authors.forename: Minoru
authors.initials: M
authors.lastname: Sakurai
authors.forename: Kouji
authors.initials: K
authors.lastname: Kanaya
authors.forename: Shin-Ichiro
authors.initials: S
authors.lastname: Kumita
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000000981:diagnostic imaging*; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D051598:Whole Body Imaging / Q000379:methods*
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18