title: Quantitative Measurements of Enhancement on Preprocedure Triphasic CT Can Predict Response of Colorectal Liver Metastases to Radioembolization.
abstract: OBJECTIVE
  Colorectal liver metastases (CLM) have a variable response to radioembolization. This may be due at least partly to differences in tumor arterial perfusion. The present study examines whether quantitative measurements of enhancement on preprocedure triphasic CT can be used to predict the response of CLM to radioembolization.
  
  
  METHODS
  We retrospectively reviewed patients with CLM treated with radioembolization who underwent pretreatment PET/CT and triphasic CT examinations and posttreatment PET/CT examinations. A total of 31 consecutive patients with 60 target tumors were included in the present study. For each tumor, we calculated the hepatic artery coefficient (HAC), portal vein coefficient (PVC), and arterial enhancement fraction (AEF) based on enhancement measurements on pretreatment triphasic CT. HAC and PVC are estimates of the hepatic artery and portal vein blood supply. AEF, which is the arterial phase enhancement divided by the portal phase enhancement, provides an estimate of the hepatic artery blood supply as a fraction of the total blood supply. For each tumor, the metabolic response to radioembolization was based on findings from the initial follow-up PET/CT scan obtained at 4-8 weeks after treatment.
  
  
  RESULTS
  A total of 55% of CLM had a complete or partial metabolic response. Arterial phase enhancement, the HAC, and the PVC did not predict which tumors responded to radioembolization. However, the AEF was statistically significantly greater in tumors with a complete or partial metabolic response than in tumors with no metabolic response (i.e., those with stable disease or disease progression) (p = 0.038). An AEF of less than 0.4 was associated with a 40% response rate, whereas an AEF greater than 0.75 was associated with a 78% response rate.
  
  
  CONCLUSIONS
  Response to radioembolization can be predicted using the AEF calculated from the preprocedure triphasic CT.
authors.affiliation: 1 Division of Interventional Radiology, Memorial Sloan Kettering Cancer Center, 1275 York Ave, New York, NY 10065.
authors.forename: F Edward
authors.initials: FE
authors.lastname: Boas
authors.affiliation: 1 Division of Interventional Radiology, Memorial Sloan Kettering Cancer Center, 1275 York Ave, New York, NY 10065.
authors.forename: Lynn A
authors.initials: LA
authors.lastname: Brody
authors.affiliation: 1 Division of Interventional Radiology, Memorial Sloan Kettering Cancer Center, 1275 York Ave, New York, NY 10065.
authors.forename: Joseph P
authors.initials: JP
authors.lastname: Erinjeri
authors.affiliation: 1 Division of Interventional Radiology, Memorial Sloan Kettering Cancer Center, 1275 York Ave, New York, NY 10065.
authors.forename: Hooman
authors.initials: H
authors.lastname: Yarmohammadi
authors.affiliation: 1 Division of Interventional Radiology, Memorial Sloan Kettering Cancer Center, 1275 York Ave, New York, NY 10065.
authors.forename: Waleed
authors.initials: W
authors.lastname: Shady
authors.affiliation: 1 Division of Interventional Radiology, Memorial Sloan Kettering Cancer Center, 1275 York Ave, New York, NY 10065.
authors.forename: Sirish
authors.initials: S
authors.lastname: Kishore
authors.affiliation: 1 Division of Interventional Radiology, Memorial Sloan Kettering Cancer Center, 1275 York Ave, New York, NY 10065.
authors.forename: Constantinos T
authors.initials: CT
authors.lastname: Sofocleous
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015179:Colorectal Neoplasms / Q000473:pathology*; D003287:Contrast Media; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007472:Iohexol; D008113:Liver Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy* / Q000556:secondary*; D008297:Male; D008863:Microspheres; D008875:Middle Aged; D000072078:Positron Emission Tomography Computed Tomography; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*; D016896:Treatment Outcome; D015021:Yttrium Radioisotopes / Q000627:therapeutic use
chemical_list: D003287:Contrast Media; D015021:Yttrium Radioisotopes; D007472:Iohexol
keywords: colorectal cancer; enhancement; liver metastasis; perfusion; yttrium-90