title: Measurement of shear wave velocity using acoustic radiation force impulse imaging is not hampered by previous use of ultrasound contrast agents.
abstract: OBJECTIVE
  To assess the inter-observer reproducibility of acoustic radiation force impulse imaging (ARFI) between 2 skilled physicians and to evaluate if ultrasound contrast agents (UCA) affect the measurement of shear wave velocity (SWV) using ARFI.
  
  
  METHODS
  53 patients (29 males, 24 females, 59 ± 15 [22-84] years) who underwent contrast enhanced ultrasound (CEUS) examination were included. ARFI was performed on liver segment V by physicians A and B before CEUS, and by physician A within 4-6 minutes and 7-10 minutes after contrast injection. In a subgroup of 31 patients (15 males, 16 females, 57 ± 18 [22-84] years), ARFI was also performed on focal liver lesions (FLL) by physician A before CEUS, and within 4-6 minutes and 7-10 minutes after contrast injection.
  
  
  RESULTS
  The SWV values obtained by physician A and B before CEUS yielded an intra-class correlation coefficient value of 0.913 (95% CI, 0.849-0.950). No significant differences were shown between the SWV values of liver segment V in all 53 patients and of FLL in the subgroup of 31 patients obtained before CEUS and that of within 4-6 minutes and 7-10 minutes after contrast injection (all P > 0.05).
  
  
  CONCLUSIONS
  ARFI showed excellent inter-observer reproducibility between 2 skilled physicians. UCA did not affect the measurement of SWV in both liver parenchyma and FLL, at least when performed 4 minutes after the contrast injection. ARFI may become an additional tool in the differential diagnosis of FLL.
authors.affiliation: Medizinische Klinik 2, Caritas Krankenhaus, Bad Mergentheim, Germany.
authors.forename: X W
authors.initials: XW
authors.lastname: Cui
authors.affiliation: Medizinische Klinik 2, Caritas Krankenhaus, Bad Mergentheim, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Pirri
authors.affiliation: Medizinische Klinik 2, Caritas Krankenhaus, Bad Mergentheim, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Ignee
authors.affiliation: Medizinische Klinik 2, Caritas Krankenhaus, Bad Mergentheim, Germany.
authors.forename: C
authors.initials: C
authors.lastname: De Molo
authors.affiliation: Innere Medizin, Deutsche Klinik für Diagnostik, Wiesbaden, Germany.
authors.forename: T O
authors.initials: TO
authors.lastname: Hirche
authors.affiliation: Pädiatrie, Caritas-Krankenhaus, Bad Mergentheim, Germany.
authors.forename: D G
authors.initials: DG
authors.lastname: Schreiber-Dietrich
authors.affiliation: Medizinische Klinik 2, Caritas Krankenhaus, Bad Mergentheim, Germany.
authors.forename: C F
authors.initials: CF
authors.lastname: Dietrich
mesh_terms: D000328:Adult; D000368:Aged; D016477:Artifacts; D003287:Contrast Media / Q000008:administration & dosage*; D055119:Elastic Modulus / Q000187:drug effects; D054459:Elasticity Imaging Techniques / Q000187:drug effects* / Q000379:methods*; D005260:Female; D006801:Humans; D008103:Liver Cirrhosis / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D033081:Shear Strength / Q000187:drug effects; D055815:Young Adult
chemical_list: D003287:Contrast Media