title: Re-evaluation of detectability of liver metastases by contrast-enhanced CT: added value of hepatic arterial phase imaging.
abstract: OBJECTIVE
  We compared the detectability of liver metastases on 2- and 3-phase images using robust statistical methods. Nine radiologists evaluated unenhanced CT plus portal venous phase (2-phase) images and 2-phase plus hepatic arterial phase (HAP) (3-phase) images.
  
  
  METHODS
  Our study included 54 patients with primary malignant tumors who underwent 3-phase hepatic dynamic CT more than twice to screen for liver metastases; 24 had 1-6 liver metastases measuring 4-27 mm in diameter (median 13 mm). The other 30 had no metastases. Nine board-certified radiologists participated in our observer performance study. They specified the location of the metastatic lesions and rated the probability of metastatic nodules on 2-phase images acquired with and without HAP imaging. We used jackknife alternative free-response receiver operating characteristic (JAFROC) analysis to compare their performances.
  
  
  RESULTS
  For all radiologists the area under the curve without and with HAP imaging was 0.86 and 0.88, respectively; the difference was significant (p = 0.04). For metastases smaller than 10 mm the averaged lesion localization fraction without and with HAP imaging was 0.17 and 0.26 (p < 0.01).
  
  
  CONCLUSIONS
  Adding HAP to 2-phase imaging improved the detectability of liver metastases, especially of lesions smaller than 10 mm.
authors.affiliation: Department of Diagnostic Radiology, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima, 734-8551, Japan.
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Honda
authors.forename: Toru
authors.initials: T
authors.lastname: Higaki
authors.forename: Haruka
authors.initials: H
authors.lastname: Higashihori
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Monzen
authors.forename: Fuminari
authors.initials: F
authors.lastname: Tatsugami
authors.forename: Shuji
authors.initials: S
authors.lastname: Date
authors.forename: Kazuo
authors.initials: K
authors.lastname: Awai
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media; D005260:Female; D006499:Hepatic Artery / Q000000981:diagnostic imaging*; D006801:Humans; D007479:Iopamidol; D008099:Liver / Q000000981:diagnostic imaging; D008113:Liver Neoplasms / Q000000981:diagnostic imaging* / Q000556:secondary; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D012372:ROC Curve; D011856:Radiographic Image Enhancement / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D007479:Iopamidol