title: Added value of subtraction imaging in detecting arterial enhancement in small (<3 cm) hepatic nodules on dynamic contrast-enhanced MRI in patients at high risk of hepatocellular carcinoma.
abstract: OBJECTIVE
  To determine the importance of arterial enhancement in diagnosing small (<3 cm) hepatocellular carcinomas (HCCs) and to evaluate the added value of dynamic subtraction magnetic resonance imaging (MRI) in detecting arterial enhancement in small (<3 cm) hepatic nodules in high-risk patients.
  
  
  METHODS
  Eighty-six patients with 135 pathologically confirmed small (<3 cm) hepatic nodules (104 HCCs, 31 benign nodules) underwent MRI before curative surgery. Arterial enhancement was determined by three methods: (1) visual assessment of the arterial phase alone, (2) visual comparison of the arterial phase with the unenhanced phase and (3) additional review of subtraction images. The diagnostic performance of each method was calculated and compared using generalised estimating equations analysis.
  
  
  RESULTS
  Arterial enhancement demonstrated high positive predictive value (PPV) (96.5-98.9 %) and specificity (90.3-96.8 %), but low negative predictive value (NPV) (54.6-62.5 %) and intermediate sensitivity (76-79.8 %) for diagnosing small HCCs. Diagnostic performance was highest for subtraction imaging. There were significant differences among the three methods in sensitivity (P = 0.04), accuracy (P = 0.044), PPV (P < 0.001) and NPV (P = 0.024), but not in specificity (P = 0.167).
  
  
  CONCLUSIONS
  The accurate detection of arterial enhancement in small hepatic nodules is important for diagnosing HCC and may be enhanced by subtraction imaging.
authors.affiliation: Department of Radiology, Research Institute of Radiological Science, Severance Hospital, Yonsei University College of Medicine, Seoul, South Korea.
authors.forename: Chansik
authors.initials: C
authors.lastname: An
authors.forename: Mi-Suk
authors.initials: MS
authors.lastname: Park
authors.forename: Dowhan
authors.initials: D
authors.lastname: Kim
authors.forename: Yeo-Eun
authors.initials: YE
authors.lastname: Kim
authors.forename: Woo-Suk
authors.initials: WS
authors.lastname: Chung
authors.forename: Hyungjin
authors.initials: H
authors.lastname: Rhee
authors.forename: Myeong-Jin
authors.initials: MJ
authors.lastname: Kim
authors.forename: Ki Whang
authors.initials: KW
authors.lastname: Kim
mesh_terms: D000328:Adult; D000368:Aged; D006528:Carcinoma, Hepatocellular / Q000473:pathology*; D003287:Contrast Media; D005260:Female; D019786:Gadolinium DTPA; D006499:Hepatic Artery / Q000473:pathology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D008113:Liver Neoplasms / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013382:Subtraction Technique
chemical_list: D003287:Contrast Media; C073590:gadolinium ethoxybenzyl DTPA; D019786:Gadolinium DTPA