title: Arterial perfusion imaging-defined subvolume of intrahepatic cancer.
abstract: OBJECTIVE
  To assess whether an increase in a subvolume of intrahepatic tumor with elevated arterial perfusion during radiation therapy (RT) predicts tumor progression after RT.
  
  
  METHODS
  Twenty patients with unresectable intrahepatic cancers undergoing RT were enrolled in a prospective, institutional review board-approved study. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) was performed before RT (pre-RT), after delivering ∼60% of the planned dose (mid-RT) and 1 month after completion of RT to quantify hepatic arterial perfusion. The arterial perfusions of the tumors at pre-RT were clustered into low-normal and elevated perfusion by a fuzzy clustering-based method, and the tumor subvolumes with elevated arterial perfusion were extracted from the hepatic arterial perfusion images. The percentage changes in the tumor subvolumes and means of arterial perfusion over the tumors from pre-RT to mid-RT were evaluated for predicting tumor progression post-RT.
  
  
  RESULTS
  Of the 24 tumors, 6 tumors in 5 patients progressed 5 to 21 months after RT completion. Neither tumor volumes nor means of tumor arterial perfusion at pre-RT were predictive of treatment outcome. The mean arterial perfusion over the tumors increased significantly at mid-RT in progressive tumors compared with the responsive tumors (P=.006). From pre-RT to mid-RT, the responsive tumors had a decrease in the tumor subvolumes with elevated arterial perfusion (median, -14%; range, -75% to 65%), whereas the progressive tumors had an increase of the subvolumes (median, 57%; range, -7% to 165%) (P=.003). Receiver operating characteristic analysis of the percentage change in the subvolume for predicting tumor progression post-RT had an area under the curve of 0.90.
  
  
  CONCLUSIONS
  The increase in the subvolume of the intrahepatic tumor with elevated arterial perfusion during RT has the potential to be a predictor for tumor progression post-RT. The tumor subvolume could be a radiation boost candidate for response-driven adaptive RT.
authors.affiliation: Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan. Electronic address: hesheng@umich.edu.
authors.forename: Hesheng
authors.initials: H
authors.lastname: Wang
authors.affiliation: Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan.
authors.forename: Reza
authors.initials: R
authors.lastname: Farjam
authors.affiliation: Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan.
authors.forename: Mary
authors.initials: M
authors.lastname: Feng
authors.affiliation: Department of Radiology, University of Michigan, Ann Arbor, Michigan.
authors.forename: Hero
authors.initials: H
authors.lastname: Hussain
authors.affiliation: Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan.
authors.forename: Randall K
authors.initials: RK
authors.lastname: Ten Haken
authors.affiliation: Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan.
authors.forename: Theodore S
authors.initials: TS
authors.lastname: Lawrence
authors.affiliation: Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan; Department of Radiology, University of Michigan, Ann Arbor, Michigan; Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan.
authors.forename: Yue
authors.initials: Y
authors.lastname: Cao
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019540:Area Under Curve; D001650:Bile Duct Neoplasms / Q000098:blood supply* / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D001653:Bile Ducts, Intrahepatic; D006528:Carcinoma, Hepatocellular / Q000098:blood supply / Q000473:pathology / Q000532:radiotherapy / Q000601:surgery; D018281:Cholangiocarcinoma / Q000098:blood supply / Q000473:pathology / Q000532:radiotherapy / Q000601:surgery; D003287:Contrast Media; D018450:Disease Progression; D005260:Female; D006499:Hepatic Artery / Q000503:physiopathology; D006801:Humans; D008113:Liver Neoplasms / Q000098:blood supply* / Q000473:pathology / Q000532:radiotherapy* / Q000556:secondary / Q000601:surgery; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D055420:Perfusion Imaging / Q000379:methods*; D011446:Prospective Studies; D012372:ROC Curve; D016634:Radiosurgery; D020266:Radiotherapy, Conformal
chemical_list: D003287:Contrast Media