title: Evaluation of optimal timing of arterial phase imaging for the detection of hypervascular hepatocellular carcinoma by using triple arterial phase imaging with multidetector-row helical computed tomography.
abstract: OBJECTIVE
  We evaluated the optimal timing of arterial phase imaging for detection of hypervascular hepatocellular carcinoma by using triple arterial phase imaging with multidetector-row helical computed tomography.
  
  
  METHODS
  Forty-nine patients with 90 hypervascular hepatocellular carcinomas (3 to 50 mm in diameter; mean, 18.7 mm) underwent triple arterial phase imaging of the whole liver using a multidetector-row helical computed tomography. At 20 seconds, 30 seconds, and 40 seconds after intravenous administration of 100 mL of 300 mgI/mL of nonionic contrast medium at a rate of 4 mL/s, early, middle, and late arterial phase images were obtained serially during a single breath-hold with an interscan delay of 5 seconds. Detector-row configurations of 4 mm x 4, scan pitch of 5.5, and scan time of 5 seconds for each phase were used. Forty prospective reconstruction images of 5-mm thickness for each phase were obtained. The images from each phase were interpreted separately for detection of hypervascular hepatocellular carcinoma by 3 observers independently who were unaware of tumor burden in the liver. Sensitivity, positive predictive value, and area under the receiver operating characteristic curve values for each arterial phase were calculated and compared statistically.
  
  
  RESULTS
  The mean sensitivity and positive predictive values for hypervascular hepatocellular carcinoma diagnosis of blind readers were 37% and 87% for the early arterial phase, 73% and 85% for the middle arterial phase, and 49% and 81% for the late arterial phase, respectively. The middle arterial phase imaging showed significantly superior sensitivity compared with the early and late arterial phase for detecting hepatocellular carcinoma (P < 0.05). Mean area under the receiver operating characteristic curve value of the middle arterial phase imaging (0.84) was significantly higher that that of the early (0.56) or late arterial phase (0.62; P < 0.05).
  
  
  CONCLUSIONS
  If a single arterial phase is used for diagnosis of hypervascular hepatocellular carcinoma, the middle phase (delay time of 30 seconds) is optimal.
authors.affiliation: Department of Radiology, Osaka University Graduate School of Medicine, Osaka, Japan. murakami@radiol.med.osaka-u.ac.jp
authors.forename: Takamichi
authors.initials: T
authors.lastname: Murakami
authors.forename: Tonsok
authors.initials: T
authors.lastname: Kim
authors.forename: Syuji
authors.initials: S
authors.lastname: Kawata
authors.forename: Masayuki
authors.initials: M
authors.lastname: Kanematsu
authors.forename: Michael P
authors.initials: MP
authors.lastname: Federle
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Hori
authors.forename: Atsuya
authors.initials: A
authors.lastname: Okada
authors.forename: Seishi
authors.initials: S
authors.lastname: Kumano
authors.forename: Eiji
authors.initials: E
authors.lastname: Sugihara
authors.forename: Kaname
authors.initials: K
authors.lastname: Tomoda
authors.forename: Hironobu
authors.initials: H
authors.lastname: Nakamura
mesh_terms: D000328:Adult; D000368:Aged; D006528:Carcinoma, Hepatocellular / Q000098:blood supply / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008099:Liver / Q000098:blood supply / Q000000981:diagnostic imaging; D008113:Liver Neoplasms / Q000098:blood supply / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity; D013997:Time Factors; D014057:Tomography, X-Ray Computed