title: Intratumoral gas in hepatocellular carcinoma following transarterial chemoembolization: associated factors and clinical impact.
abstract: OBJECTIVE
  To determine the frequency and factors associated with the presence of intratumoral gas-containing areas in hepatocellular carcinoma (HCC) on computed tomography (CT) scans obtained 4-6 weeks after transarterial chemoembolization.
  
  
  METHODS
  From June 2010 to December 2011, 201 patients underwent 286 chemoembolization procedures for HCC (n = 497 tumors) and were retrospectively included. The presence of intratumoral gas was assessed on CT 4-6 weeks after chemoembolization. Clinical and biologic data and tumoral and chemoembolization procedure characteristics were noted. Factors associated with the presence of intratumoral gas were evaluated. Tumor response was assessed by using European Society for the Study of the Liver criteria. Tumors containing gas or not containing gas were compared by univariate and multivariate analysis.
  
  
  RESULTS
  Intratumoral gas was found in 26 tumors (5%) after 26 chemoembolization procedures (9.1%) in 26 patients (13%). Gas was related to abscess formation in three patients (11.5%). On multivariate analysis, a large mean tumor diameter at baseline (72.4 mm vs 40.2 mm; P = .003), chemoembolization with drug-eluting beads (P = .033), and superselective approach (P = .024) were independently associated with the presence of gas. Tumors that exhibited gas-containing areas at 1 month had a significantly higher objective response rate than those that did not (P < .0001).
  
  
  CONCLUSIONS
  Intratumoral gas-containing areas after chemoembolization are rarely related to the formation of abscesses. The presence of intratumoral gas on CT 4-6 weeks after chemoembolization could be a surrogate marker for marked tumor necrosis.
authors.affiliation: Department of Radiology, Assistance Publique Hôpitaux de Paris, University Paris Diderot, Sorbonne Paris Cité, University Hospitals Paris Nord Val de Seine, Hôpital Beaujon, Assistance Publique Hôpitaux de Paris, 100 Boulevard du Général Leclerc, 92118 Clichy, France.
authors.forename: Damien
authors.initials: D
authors.lastname: Bisseret
authors.forename: Maxime
authors.initials: M
authors.lastname: Ronot
authors.forename: Mohamed
authors.initials: M
authors.lastname: Abdel-Rehim
authors.forename: Annie
authors.initials: A
authors.lastname: Sibert
authors.forename: Mohamed
authors.initials: M
authors.lastname: Bouattour
authors.forename: Laurent
authors.initials: L
authors.lastname: Castera
authors.forename: Jacques
authors.initials: J
authors.lastname: Belghiti
authors.forename: Valérie
authors.initials: V
authors.lastname: Vilgrain
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D006528:Carcinoma, Hepatocellular / Q000000981:diagnostic imaging / Q000473:pathology / Q000628:therapy*; D016461:Chemoembolization, Therapeutic / Q000009:adverse effects; D016009:Chi-Square Distribution; D005260:Female; D005740:Gases; D006801:Humans; D008100:Liver Abscess / Q000000981:diagnostic imaging / Q000209:etiology / Q000473:pathology; D008113:Liver Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000628:therapy*; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D061330:Multidetector Computed Tomography; D015999:Multivariate Analysis; D009336:Necrosis; D012189:Retrospective Studies; D013997:Time Factors; D016896:Treatment Outcome; D047368:Tumor Burden
chemical_list: D005740:Gases
keywords: 3D; EASL; European Association for the Study of the Liver; HCC; hepatocellular carcinoma; three-dimensional