title: CT Evaluation of the progression of hypoattenuating nodular lesions in virus-related chronic liver disease.
abstract: OBJECTIVE
  The purpose of this study was to clarify the natural outcomes of hypoattenuating nodular lesions in patients with virus-related chronic liver disease depicted on dynamic CT.
  
  
  METHODS
  Sixty lesions (mean size, 1.3 cm) exhibiting hypoattenuation or isoattenuation in the arterial and delayed phases of dynamic CT were retrospectively evaluated with additional CT (mean, six examinations) for a mean period of 838 days. The primary end point was emergence of hyperattenuating areas within hypoattenuating lesions, a phenomenon called attenuation conversion. Cumulative attenuation conversion rates suggesting rates of malignant transformation were calculated with the Kaplan-Meier method, and factors affecting attenuation conversion rate were analyzed with the Cox proportional hazard model.
  
  
  RESULTS
  Thirty-six (60%) of 60 hypoattenuating lesions developed to hyperattenuating lesions, 21 were unchanged, and three disappeared spontaneously. The 36 lesions that became hyperattenuating were divided into two subgroups according to lesion enhancement pattern: hyper-in-hypoattenuating (n = 25) and entirely hyperattenuating (n = 11). The cumulative attenuation conversion rates for the 60 hypoattenuating lesions were 15.8%, 44.3%, and 58.7% at 1, 2, and 3 years. The hyper-in-hypoattenuating lesions showed more rapid progression to entirely enhanced lesions. Positive results for hepatitis C viral antibody (p = 0.028) and initial lesion size (p = 0.007) showed a positive correlation with attenuation conversion rate.
  
  
  CONCLUSIONS
  Hypoattenuating hepatic nodular lesions in chronic liver disease depicted on dynamic CT have high malignant potential and should be followed with special attention to conversion from hypoattenuation to hyperattenuation to determine the optimal timing of treatment.
authors.affiliation: Department of Diagnostic Radiology, National Cancer Center Hospital, 5-1-1, Tsukiji, Chuo-ku, Tokyo 104-0045, Japan. ktakayas@ncc.go.jp
authors.forename: Kenichi
authors.initials: K
authors.lastname: Takayasu
authors.forename: Yukio
authors.initials: Y
authors.lastname: Muramatsu
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Mizuguchi
authors.forename: Takuji
authors.initials: T
authors.lastname: Okusaka
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Shimada
authors.forename: Tadatoshi
authors.initials: T
authors.lastname: Takayama
authors.forename: Michiie
authors.initials: M
authors.lastname: Sakamoto
mesh_terms: D000368:Aged; D006528:Carcinoma, Hepatocellular / Q000150:complications* / Q000000981:diagnostic imaging*; D018450:Disease Progression; D005260:Female; D019694:Hepatitis B, Chronic / Q000150:complications* / Q000000981:diagnostic imaging*; D019698:Hepatitis C, Chronic / Q000150:complications* / Q000000981:diagnostic imaging*; D006801:Humans; D008113:Liver Neoplasms / Q000150:complications* / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed