title: Transient hepatic echogenicity difference on contrast-enhanced ultrasonography: sonographic sign and pitfall.
abstract: OBJECTIVE
  The purpose of this study was to report and analyze a new contrast-enhanced ultrasonographic (CEUS) imaging finding, the transient hepatic echogenicity difference due to perfusion changes, using computed tomography (CT) as a reference standard.
  
  
  METHODS
  We retrospectively investigated the records of patients evaluated in a 2-year period, selecting those who had undergone both CT and CEUS within 15 days, who had CT evidence of a perfusion abnormality, and who had had a CEUS study that included the malperfused parenchymal area.
  
  
  RESULTS
  There were 30 patients with 44 hepatic perfusion changes on CT scans (28 around liver focal lesions and 16 unrelated to focal lesions). Retrospectively, CEUS allowed recognition of 21 of 28 perifocal transient hepatic attenuation differences (THADs), 6 of 10 subsegmental THADs, 2 of 3 segmental THADs, and 1 of 3 lobar THADs. Only some of these abnormalities had been identified at the original CEUS examinations: 0 of 3 lobar THADs, 1 of 3 segmental THADs, 2 of 10 subsegmental THADs, and 16 of 28 perifocal THADs.
  
  
  CONCLUSIONS
  Contrast-enhanced ultrasonography can show hepatic perfusion abnormalities similar to those well known from CT literature, although with a lower sensitivity. Knowledge of this transient hepatic echogenicity difference phenomenon may be relevant for avoiding incorrect image interpretation or incorrect tumor size measurement and for eventually identifying occult vascular disorders such as venous thrombosis or fistulas.
authors.affiliation: Department of radiology, National Cancer Institute Fondazione G. Pascale, Naples, Italy. orlandcat@tin.it
authors.forename: Orlando
authors.initials: O
authors.lastname: Catalano
authors.forename: Fabio
authors.initials: F
authors.lastname: Sandomenico
authors.forename: Antonio
authors.initials: A
authors.lastname: Nunziata
authors.forename: Mauro Mattace
authors.initials: MM
authors.lastname: Raso
authors.forename: Paolo
authors.initials: P
authors.lastname: Vallone
authors.forename: Alfredo
authors.initials: A
authors.lastname: Siani
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D006528:Carcinoma, Hepatocellular / Q000000981:diagnostic imaging* / Q000556:secondary; D003287:Contrast Media; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008099:Liver / Q000098:blood supply / Q000000981:diagnostic imaging*; D008102:Liver Circulation / Q000502:physiology*; D008113:Liver Neoplasms / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D010743:Phospholipids; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013459:Sulfur Hexafluoride; D014057:Tomography, X-Ray Computed; D014463:Ultrasonography / Q000379:methods
chemical_list: D003287:Contrast Media; D010743:Phospholipids; C420843:contrast agent BR1; D013459:Sulfur Hexafluoride