title: Multidetector CT: diagnostic impact of slice thickness on detection of hypervascular hepatocellular carcinoma.
abstract: OBJECTIVE
  The objective of our study was to evaluate the diagnostic impact of varying slice thickness on multidetector CT to optimize detection of hypervascular hepatocellular carcinoma.
  
  
  METHODS
  Forty-three patients with 87 hypervascular hepatocellular carcinomas (diameter: range, 3-80 mm; mean, 22 mm) and 19 patients with either chronic hepatitis or liver cirrhosis and without hepatocellular carcinoma who had undergone early arterial and late arterial phase imaging of the entire liver on multidetector CT were retrospectively enrolled in this study. The detector row configuration was 2.5 x 4 mm, the pitch was 6, and the scanning time was 10.5 sec for each phase. All patients received contrast medium (2 mL/kg of body weight) at a rate of 5 mL/sec; the mean scanning delay for the early arterial phase was 19.0 sec, and the mean delay for the late arterial phase was 34.5 sec. Eighty 2.5-mm-thick reconstruction images, forty 5-mm-thick reconstruction images, and twenty-six 7.5-mm-thick reconstruction images were obtained for each phase. Each image set was interpreted separately by three observers to detect hypervascular hepatocellular carcinoma by viewing images on a workstation monitor. Sensitivity, positive predictive value, and area under the receiver operating characteristic curve (A(z)) were calculated. We used retrospectively excellent follow-up and imaging or pathologic proof as the gold standard.
  
  
  RESULTS
  The mean sensitivity and positive predictive value for hypervascular hepatocellular carcinoma were 76% and 69% on 2.5-mm images, 73% and 69% on 5-mm images, and 67% and 76% on 7.5-mm images, respectively. No significant difference in sensitivity among the images was detected, except by one observer who reported a significant difference in the sensitivity between 2.5- and 7.5-mm images (p < 0.05) and between 5- and 7.5-mm images (p < 0.05). The mean A(z) values were 0.79, 0.80, and 0.78 for 2.5-, 5-, and 7.5-mm images, respectively. No significant difference in A(z) values among the images obtained with different slice thicknesses was detected.
  
  
  CONCLUSIONS
  For multidetector CT identification of hypervascular hepatocellular carcinoma, we found little or no advantage in reducing slice thickness to less than 5 mm.
authors.affiliation: Department of Radiology, Osaka University Graduate School of Medicine D1, 2-2 Yamadaoka, Suita City, Osaka, 565-0871 Japan.
authors.forename: Shuji
authors.initials: S
authors.lastname: Kawata
authors.forename: Takamichi
authors.initials: T
authors.lastname: Murakami
authors.forename: Tonsok
authors.initials: T
authors.lastname: Kim
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Hori
authors.forename: Michael P
authors.initials: MP
authors.lastname: Federle
authors.forename: Seishi
authors.initials: S
authors.lastname: Kumano
authors.forename: Eiji
authors.initials: E
authors.lastname: Sugihara
authors.forename: Shigeru
authors.initials: S
authors.lastname: Makino
authors.forename: Hironobu
authors.initials: H
authors.lastname: Nakamura
authors.forename: Masayuki
authors.initials: M
authors.lastname: Kudo
mesh_terms: D000328:Adult; D000368:Aged; D006528:Carcinoma, Hepatocellular / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008099:Liver / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D008102:Liver Circulation / Q000502:physiology*; D008113:Liver Neoplasms / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012372:ROC Curve; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D019043:Vascular Neoplasms / Q000000981:diagnostic imaging* / Q000503:physiopathology*