title: Inflammatory myofibroblastic tumours of the liver: gadoxetic acid-enhanced and diffusion-weighted MRI findings with 18F-FDG PET/CT and clinical significance of regression on follow-up.
abstract: OBJECTIVE
  To assess gadoxetic acid-enhanced and diffusion-weighted (DW) magnetic resonance imaging (MRI) findings of inflammatory myofibroblastic tumours (IMTs) of the liver using combined 2-[(18)F]-fluoro-2-deoxy-D-glucose (FDG) positron-emission tomography (PET)/computed tomography (CT), and to evaluate clinical course with volume change on follow-up.
  
  
  METHODS
  Gadoxetic acid-enhanced and DW MRI findings of 18 histopathologically proven hepatic IMTs in 13 patients were retrospectively reviewed. The clinical features, qualitative (signal intensity and enhancement pattern) and quantitative data [apparent diffusion coefficient (ADC)], and analysis of FDG-PET/CT findings were collected. The volume of IMTs during follow-up was measured using a tumour half-time.
  
  
  RESULTS
  Most of the IMTs (9/13, 69.2%) were found incidentally. IMTs were predominantly seen as well-defined (16/18, 88.9%) masses with peritumoural hypointensity during the hepatobiliary phase (17/18, 94.4%) and showed five morphological types: target-like hypervascular mass (n = 9), hypovascular mass (n = 5), heterogeneous enhancing mass (n = 2), sclerosing mass (n = 1), and non-target hypervascular mass (n = 1). All lesions showed diffusion restriction and hypermetabolic mass on FDG-PET/CT images. The mean ADC value and ADC ratio of IMTs to liver were 0.828 × 10(-3) mm(2)/s and 0.76, respectively. On follow-up, all 11 IMTs showed rapid regression (mean tumour half-time, 38.49 days) with no tumour recurrence or distant metastasis.
  
  
  CONCLUSIONS
  Although hepatic IMTs can mimic abscess and malignant tumours at MRI and PET/CT, peritumoural hypointensity during the hepatobiliary phase with rapid regression on follow-up could be helpful for differentiating it from other lesions.
authors.affiliation: Departments of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: T W
authors.initials: TW
authors.lastname: Kang
authors.affiliation: Departments of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea. Electronic address: kshyun@skku.edu.
authors.forename: S H
authors.initials: SH
authors.lastname: Kim
authors.affiliation: Departments of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: K M
authors.initials: KM
authors.lastname: Jang
authors.affiliation: Departments of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: D
authors.initials: D
authors.lastname: Choi
authors.affiliation: Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: J Y
authors.initials: JY
authors.lastname: Choi
authors.affiliation: Department of Pathology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: C K
authors.initials: CK
authors.lastname: Park
mesh_terms: D000328:Adult; D000368:Aged; D003287:Contrast Media; D003937:Diagnosis, Differential; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D019788:Fluorodeoxyglucose F18; D005500:Follow-Up Studies; D019786:Gadolinium DTPA; D006801:Humans; D008113:Liver Neoplasms / Q000175:diagnosis* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D049268:Positron-Emission Tomography / Q000379:methods; D019275:Radiopharmaceuticals; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media; D019275:Radiopharmaceuticals; C073590:gadolinium ethoxybenzyl DTPA; D019788:Fluorodeoxyglucose F18; D019786:Gadolinium DTPA