title: Computed tomographic perfusion imaging for the prediction of response and survival to transarterial radioembolization of liver metastases.
abstract: OBJECTIVE
  The purpose of this study was to evaluate prospectively, in patients with liver metastases, the ability of computed tomographic (CT) perfusion to predict the morphologic response and survival after transarterial radioembolization (TARE).
  
  
  METHODS
  Thirty-eight patients (22 men; mean [SD] age, 63 [12] years) with otherwise therapy-refractory liver metastases underwent dynamic, contrast-enhanced CT perfusion within 1 hour before treatment planning catheter angiography, for calculation of the arterial perfusion (AP) of liver metastases, 20 days before TARE with Yttrium-90 microspheres. Treatment response was evaluated morphologically on follow-up imaging (mean, 114 days) on the basis of the Response Evaluation Criteria in Solid Tumors criteria (version 1.1). Pretreatment CT perfusion was compared between responders and nonresponders. One-year survival was calculated including all 38 patients using the Kaplan-Meier curves; the Cox proportional hazard model was used for calculating predictors of survival.
  
  
  RESULTS
  Follow-up imaging was not available in 11 patients because of rapidly deteriorating health or death. From the remaining 27, a total of 9 patients (33%) were classified as responders and 18 patients (67%) were classified as nonresponders. A significant difference in AP was found on pretreatment CT perfusion between the responders and the nonresponders to the TARE (P < 0.001). Change in tumor size on the follow-up imaging correlated significantly and negatively with AP before the TARE (r = -0.60; P = 0.001). Receiver operating characteristics analysis of AP in relation to treatment response revealed an area under the curve of 0.969 (95% confidence interval, 0.911-1.000; P < 0.001). A cutoff AP of 16 mL per 100 mL/min was associated with a sensitivity of 100% (9/9) (95% CI, 70%-100%) and a specificity of 89% (16/18) (95% CI, 62%-96%) for predicting therapy response. A significantly higher 1-year survival after the TARE was found in the patients with a pretreatment AP of 16 mL per 100 mL/min or greater (P = 0.028), being a significant, independent predictor of survival (hazard ratio, 0.101; P = 0.015).
  
  
  CONCLUSIONS
  Arterial perfusion of liver metastases, as determined by pretreatment CT perfusion imaging, enables prediction of short-term morphologic response and 1-year survival to TARE.
authors.affiliation: From the *Institute of Diagnostic and Interventional Radiology, and †Division of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland; ‡Imaging and Therapy Systems Division, Siemens Healthcare, Forchheim, Germany; §Clinic for Oncology, University Hospital Zurich; and ∥Division of Biostatistics, Institute for Social and Preventive Medicine, University of Zurich, Zurich, Switzerland.
authors.forename: Fabian
authors.initials: F
authors.lastname: Morsbach
authors.forename: Thomas
authors.initials: T
authors.lastname: Pfammatter
authors.forename: Caecilia S
authors.initials: CS
authors.lastname: Reiner
authors.forename: Michael A
authors.initials: MA
authors.lastname: Fischer
authors.forename: Bert-Ram
authors.initials: BR
authors.lastname: Sah
authors.forename: Sebastian
authors.initials: S
authors.lastname: Winklhofer
authors.forename: Ernst
authors.initials: E
authors.lastname: Klotz
authors.forename: Thomas
authors.initials: T
authors.lastname: Frauenfelder
authors.forename: Alexander
authors.initials: A
authors.lastname: Knuth
authors.forename: Burkhardt
authors.initials: B
authors.lastname: Seifert
authors.forename: Niklaus
authors.initials: N
authors.lastname: Schaefer
authors.forename: Hatem
authors.initials: H
authors.lastname: Alkadhi
mesh_terms: D000792:Angiography; D001158:Arteries; D003287:Contrast Media; D005260:Female; D006801:Humans; D007472:Iohexol / Q000031:analogs & derivatives; D008099:Liver / Q000098:blood supply / Q000473:pathology; D008113:Liver Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy* / Q000556:secondary*; D008297:Male; D008863:Microspheres; D008875:Middle Aged; D011446:Prospective Studies; D019275:Radiopharmaceuticals / Q000627:therapeutic use; D015996:Survival Rate; D014057:Tomography, X-Ray Computed / Q000379:methods*; D016896:Treatment Outcome; D015021:Yttrium Radioisotopes / Q000627:therapeutic use
chemical_list: D003287:Contrast Media; D019275:Radiopharmaceuticals; D015021:Yttrium Radioisotopes; D007472:Iohexol; C038192:iopromide