title: Differentiation of malignant tumours from granulomas by using dynamic [(18)F]-fluoro-L-α-methyltyrosine positron emission tomography.
abstract: BACKGROUND
  Previous clinical studies have revealed the potential of [(18)F]-fluoro-L-α-methyltyrosine ((18)F-FAMT) for the differential diagnosis of malignant tumours from sarcoidosis. However, one concern regarding the differential diagnosis with (18)F-FAMT is the possibility of false negatives given the small absolute uptake of (18)F-FAMT that has been observed in some malignant tumours. The aim of this study was to evaluate a usefulness of dynamic (18)F-FAMT positron emission tomography (PET) for differentiating malignant tumours from granulomas.
  
  
  METHODS
  Rats bearing both granulomas (Mycobacterium bovis bacillus Calmette-Guérin (BCG)-induced) and tumours (C6 glioma cell-induced) underwent dynamic 2-deoxy-2-[(18)F]-fluoro-D-glucose ((18)F-FDG) PET and (18)F-FAMT PET for 120 min on consecutive days. Time-activity curves, static images, mean standardized uptake values (SUVs) and the SUV ratios (SUVRs; calculated by dividing SUV at each time point by that of 2 min after injection) were assessed.
  
  
  RESULTS
  In tumours, (18)F-FAMT showed a shoulder peak immediately after the initial distribution followed by gradual clearance compared with granulomas. Although the mean SUV in the tumours (1.00 ± 0.10) was significantly higher than that in the granulomas (0.88 ± 0.12), a large overlap was observed. In contrast, the SUVR was markedly higher in tumours than in granulomas (50 min/2 min, 0.72 ± 0.06 and 0.56 ± 0.05, respectively) with no overlap. The dynamic patterns, SUVR, and mean SUV of (18)F-FDG in the granulomas were comparable to those in the tumours.
  
  
  CONCLUSIONS
  Dynamic (18)F-FAMT and SUVR analysis might compensate for the current limitations and help in improving the diagnostic accuracy of (18)F-FAMT.
authors.affiliation: Department of Bioimaging Information Analysis, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Japan.
authors.forename: Aiko
authors.initials: A
authors.lastname: Yamaguchi
authors.affiliation: Department of Bioimaging Information Analysis, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Japan.
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Hanaoka
authors.affiliation: Faculty of Pharmaceutical Sciences, Suzuka University of Medical Science, 3500-3 Minamitamagaki-Cho, Suzuka, Mie 510-8760 Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Fujisawa
authors.affiliation: Department of Tracer Kinetics & Bioanalysis, Graduate School of Medicine, Hokkaido University, 5 Chome Kita 8 Jōnishi, Sapporo, Japan ; Department of Molecular Imaging, Graduate School of Medicine, Hokkaido University, 5 Chome Kita 8 Jōnishi, Sapporo, Japan.
authors.forename: Songji
authors.initials: S
authors.lastname: Zhao
authors.affiliation: Department of Parasitology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Japan.
authors.forename: Kazutomo
authors.initials: K
authors.lastname: Suzue
authors.affiliation: Faculty of Pharmaceutical Sciences, Suzuka University of Medical Science, 3500-3 Minamitamagaki-Cho, Suzuka, Mie 510-8760 Japan.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Morita
authors.affiliation: Advanced Clinical Research Center, Fukushima Medical University, 1 Hikariga-oka, Fukushima, Japan.
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Tominaga
authors.affiliation: Department of Diagnostic Radiology and Nuclear Medicine, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Japan.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Higuchi
authors.affiliation: Department of Parasitology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Japan.
authors.forename: Hajime
authors.initials: H
authors.lastname: Hisaeda
authors.affiliation: Department of Diagnostic Radiology and Nuclear Medicine, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Japan.
authors.forename: Yoshito
authors.initials: Y
authors.lastname: Tsushima
authors.affiliation: Department of Integrated Molecular Imaging, Graduate School of Medicine, Hokkaido University, 5 Chome Kita 8 Jōnishi, Sapporo, Japan ; Central Institute of Isotope Science, Hokkaido University, 5 Chome Kita 8 Jōnishi, Sapporo, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Kuge
authors.affiliation: Department of Bioimaging Information Analysis, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Japan ; Faculty of Pharmaceutical Sciences, Suzuka University of Medical Science, 3500-3 Minamitamagaki-Cho, Suzuka, Mie 510-8760 Japan.
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Iida
keywords: 3-[18F]-Fluoro-α-methyl-L-tyrosine; Dynamic positron emission tomography; Granuloma; Inflammation; Tumour