title: Threshold doses for focal liver reaction after stereotactic ablative body radiation therapy for small hepatocellular carcinoma depend on liver function: evaluation on magnetic resonance imaging with Gd-EOB-DTPA.
abstract: OBJECTIVE
  Focal liver reaction (FLR) appears on radiographic images after stereotactic ablative body radiation therapy (SABR) in patients with hepatocellular carcinoma (HCC) and chronic liver disease. We investigated the threshold dose (TD) of FLR and possible factors affecting the TD on gadoxetate acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI).
  
  
  METHODS
  In 50 patients who were treated with SABR for small HCC and followed up by MRI for >6 months, FLR, seen as a hypointense area, was evaluated on the hepatobiliary phase of Gd-EOB-DTPA-enhanced MRI. The follow-up MRI with the largest extent of FLR was fused to the planning computed tomography (CT) image, and patients with good image fusion concordance were eligible. After delineating the border of the FLR manually, a dose-volume histogram was used to identify the TD for the FLR. Clinical and volumetric factors were analyzed for correlation with the TD.
  
  
  RESULTS
  A total of 45 patients were eligible for analysis with a median image fusion concordance of 84.9% (range, 71.6-95.4%). The median duration between SABR and subsequent hepatobiliary phase MRI with the largest extent of FLR was 3 months (range, 1-6 months). The median TD for FLR was 28.0 Gy (range, 22.3-36.4 Gy). On univariate analysis, pre-treatment Child-Pugh (CP) score and platelet count were significantly correlated with the TD. On multiple linear regression analysis, CP score was the only parameter that predicted TD. Median TDs were 30.5 Gy (range, 26.2.3-36.4 Gy) and 25.2 Gy (range, 22.3-27.5 Gy) for patients with CP-A and CP-B disease, respectively.
  
  
  CONCLUSIONS
  The TD was significantly correlated with baseline liver function. We propose 30 Gy for CP-A disease and 25 Gy for CP-B disease in 5 fractions as TDs for FLR after SABR for patients with HCC and chronic liver disease. Use of these TDs will help to predict potential loss of liver tissue after SABR.
authors.affiliation: Radiation Oncology Center, Ofuna Chuo Hospital, Kanagawa, Japan; Department of Radiation Oncology, Tokai University, Kanagawa, Japan.
authors.forename: Naoko
authors.initials: N
authors.lastname: Sanuki
authors.affiliation: Radiation Oncology Center, Ofuna Chuo Hospital, Kanagawa, Japan; Department of Radiation Oncology, Tokai University, Kanagawa, Japan.
authors.forename: Atsuya
authors.initials: A
authors.lastname: Takeda
authors.affiliation: Radiation Oncology Center, Ofuna Chuo Hospital, Kanagawa, Japan; Department of Radiation Oncology, Tokai University, Kanagawa, Japan.
authors.forename: Yohei
authors.initials: Y
authors.lastname: Oku
authors.affiliation: Radiation Oncology Center, Ofuna Chuo Hospital, Kanagawa, Japan.
authors.forename: Takahisa
authors.initials: T
authors.lastname: Eriguchi
authors.affiliation: Radiation Oncology Center, Ofuna Chuo Hospital, Kanagawa, Japan.
authors.forename: Shuichi
authors.initials: S
authors.lastname: Nishimura
authors.affiliation: Radiation Oncology Center, Ofuna Chuo Hospital, Kanagawa, Japan.
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Aoki
authors.affiliation: Department of Radiology, Ofuna Chuo Hospital, Kanagawa, Japan.
authors.forename: Tomikazu
authors.initials: T
authors.lastname: Mizuno
authors.affiliation: Department of Hepatology and Gastroenterology, Ofuna Chuo Hospital, Kanagawa, Japan.
authors.forename: Shogo
authors.initials: S
authors.lastname: Iwabuchi
authors.affiliation: Department of Radiation Oncology, Tokai University, Kanagawa, Japan. Electronic address: kunieda-mi@umin.ac.jp.
authors.forename: Etsuo
authors.initials: E
authors.lastname: Kunieda
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D006528:Carcinoma, Hepatocellular / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D008099:Liver / Q000473:pathology / Q000503:physiopathology / Q000528:radiation effects*; D008113:Liver Neoplasms / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D016634:Radiosurgery / Q000009:adverse effects / Q000379:methods*; D011879:Radiotherapy Dosage
chemical_list: C073590:gadolinium ethoxybenzyl DTPA; D019786:Gadolinium DTPA