title: Stereotactic body radiotherapy-induced arterial hypervascularity of non-tumorous hepatic parenchyma in patients with hepatocellular carcinoma: potential pitfalls in tumor response evaluation on multiphase computed tomography.
abstract: OBJECTIVE
  To evaluate temporal changes in contrast enhancement patterns of non-tumorous hepatic parenchyma with a focus on arterial hypervascularity on multiphase computed tomography (CT) in patients with hepatocellular carcinoma (HCC) treated with stereotactic body radiotherapy (SBRT).
  
  
  METHODS
  We retrospectively identified 61 patients who had undergone multiphase contrast-enhanced CT at one, three, and six months after SBRT. Irradiated versus non-irradiated liver parenchyma was delineated by cross-correlation with the dose-volume histogram of SBRT plan. Serial changes in the contrast enhancement patterns of the irradiated versus non-irradiated liver parenchyma were evaluated by two abdominal radiologists in consensus. We compared the frequency of the contrast enhancement patterns according to the follow-up period using the Fisher-Freeman-Halton exact test.
  
  
  RESULTS
  The irradiated non-tumorous hepatic parenchyma showed that the prevalence of arterial hypervascularity increased during the follow-up period (P<.01): 11.5% (7/61) in one, 45.9% (28/61) in three, and 54.1% (33/61) in six months. Contrast wash-out on the delayed phase was uncommon: 1.6% (1/61) in one, 3.3% (2/61) in three, and 0% in six months.
  
  
  CONCLUSIONS
  The incidence of arterial hypervascularity of the irradiated hepatic parenchyma gradually increased until six months after SBRT, which could interfere with the accurate evaluation of treatment response. The lack of wash-out on the delayed phase in the hypervascular area would distinguish SBRT-related change from residual/recurred HCC.
authors.affiliation: Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: Mee Jin
authors.initials: MJ
authors.lastname: Park
authors.affiliation: Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: So Yeon
authors.initials: SY
authors.lastname: Kim
authors.affiliation: Department of Radiation Oncology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: Sang Min
authors.initials: SM
authors.lastname: Yoon
authors.affiliation: Department of Radiation Oncology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: Jong Hoon
authors.initials: JH
authors.lastname: Kim
authors.affiliation: Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: Seong Ho
authors.initials: SH
authors.lastname: Park
authors.affiliation: Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: Seung Soo
authors.initials: SS
authors.lastname: Lee
authors.affiliation: Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: Yedaun
authors.initials: Y
authors.lastname: Lee
authors.affiliation: Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: Moon-Gyu
authors.initials: MG
authors.lastname: Lee
mesh_terms: D000368:Aged; D006528:Carcinoma, Hepatocellular / Q000098:blood supply / Q000175:diagnosis* / Q000473:pathology / Q000532:radiotherapy; D003287:Contrast Media / Q000737:chemistry; D005260:Female; D006801:Humans; D008099:Liver / Q000098:blood supply / Q000473:pathology / Q000528:radiation effects*; D008113:Liver Neoplasms / Q000098:blood supply / Q000175:diagnosis* / Q000473:pathology / Q000532:radiotherapy; D008297:Male; D008875:Middle Aged; D016634:Radiosurgery; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods; D059016:Tumor Microenvironment
chemical_list: D003287:Contrast Media