title: Differentiation of focal liver lesions: usefulness of parametric imaging with contrast-enhanced US.
abstract: OBJECTIVE
  To evaluate whether parametric imaging with contrast material-enhanced ultrasonography (US) is superior to visual assessment for the differential diagnosis of focal liver lesions (FLLs).
  
  
  METHODS
  This study had institutional review board approval, and verbal patient informed consent was obtained. Between August 2005 and October 2008, 146 FLLs in 145 patients (63 women, 82 men; mean age, 62.5 years; age range, 22-89 years) were imaged with real-time low-mechanical-index contrast-enhanced US after a bolus injection of 2.4 mL of a second-generation contrast agent. Clips showing contrast agent uptake kinetics (including arterial, portal, and late phases) were recorded and subsequently analyzed off-line with dedicated image processing software. Analysis of the dynamic vascular patterns (DVPs) of lesions with respect to adjacent parenchyma allowed mapping DVP signatures on a single parametric image. Cine loops of contrast-enhanced US and results from parametric imaging of DVP were assessed separately by three independent off-site readers who classified each lesion as benign, malignant, or indeterminate. Sensitivity, specificity, accuracy, and positive and negative predictive values were calculated for both techniques. Interobserver agreement (κ statistics) was determined.
  
  
  RESULTS
  Sensitivities for visual interpretation of cine loops for the three readers were 85.0%, 77.9%, and 87.6%, which improved significantly to 96.5%, 97.3%, and 96.5% for parametric imaging, respectively (P < .05, McNemar test), while retaining high specificity (90.9% for all three readers). Accuracy scores of parametric imaging were higher than those of conventional contrast-enhanced US for all three readers (P < .001, McNemar test). Interobserver agreement increased with DVP parametric imaging compared with conventional contrast-enhanced US (change of κ from 0.54 to 0.99).
  
  
  CONCLUSIONS
  Parametric imaging of DVP improves diagnostic performance of contrast-enhanced US in the differentiation between malignant and benign FLLs; it also provides excellent interobserver agreement.
authors: Department of Diagnostic and Interventional Radiology and Center for Clinical Epidemiology, Institute for Social and Preventive Medicine, University Hospital Lausanne, Switzerland. aanaye@ulb.ac.be
authors: Anass
authors: A
authors: Anaye
authors: Geneviève
authors: G
authors: Perrenoud
authors: Nicolas
authors: N
authors: Rognin
authors: Marcel
authors: M
authors: Arditi
authors: Laurent
authors: L
authors: Mercier
authors: Peter
authors: P
authors: Frinking
authors: Christiane
authors: C
authors: Ruffieux
authors: Philippe
authors: P
authors: Peetrons
authors: Reto
authors: R
authors: Meuli
authors: Jean-Yves
authors: JY
authors: Meuwly
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008113:Liver Neoplasms / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D014463:Ultrasonography; D055815:Young Adult
chemical_list: D003287:Contrast Media