title: Enhanced sonography using carbon dioxide gas for small hepatocellular carcinoma: a comparison study between pure carbon dioxide gas and carbon dioxide microbubbles.
abstract: OBJECTIVE
  To evaluate the feasibility of enhanced sonography using arterial injection of pure carbon dioxide gas (CO(2)) for detecting small hepatocellular carcinoma (HCC) nodules.
  
  
  METHODS
  We performed enhanced sonography on 51 HCC nodules of 35 patients with HCC. The patients underwent enhanced sonography with two methods: injection of pure CO(2) (26 nodules), or injection of CO(2) microbubbles (25 nodules) using CO(2) and soy bean oil. We observed the enhancement effect of HCC on enhanced sonography, and measured the accumulation time of CO(2) in the nodules.
  
  
  RESULTS
  Twenty-three nodules appeared hyperechoic on enhanced sonography, and 12 of the nodules could be found on enhanced sonography only. Sixteen of the hyperechoic nodules on baseline sonography revealed no enhancement. Multiple regression analysis with regard to the method of injection of CO(2), nodule location, and nodule size revealed that method (p<0.0001) and nodule size (p=0.02) remained significant. The accumulation time of CO(2) microbubbles in the nodules was 4.4+/-0.8 minutes, whereas pure CO(2) accumulation time was 14.7+/-1.5 minutes, significantly longer than the CO(2) microbubbles regardless of nodule size and location.
  
  
  CONCLUSIONS
  Enhanced sonography of arterial injection of pure CO(2) is a feasible technique for detecting small HCC nodules.
authors.affiliation: Department of Radiology, Sapporo Medical University, Hokkaido, Japan.
authors.forename: Kazumitsu
authors.initials: K
authors.lastname: Koito
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Namieno
authors.forename: Naoki
authors.initials: N
authors.lastname: Hirokawa
authors.forename: Takeshi
authors.initials: T
authors.lastname: Ichimura
authors.forename: Mutsumi
authors.initials: M
authors.lastname: Nishida
authors.forename: Naoya
authors.initials: N
authors.lastname: Yama
authors.forename: Koichi
authors.initials: K
authors.lastname: Sakata
authors.forename: Masato
authors.initials: M
authors.lastname: Hareyama
authors.forename: Motoi
authors.initials: M
authors.lastname: Nish
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002245:Carbon Dioxide / Q000008:administration & dosage; D006528:Carcinoma, Hepatocellular / Q000000981:diagnostic imaging*; D003287:Contrast Media / Q000008:administration & dosage; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D008113:Liver Neoplasms / Q000000981:diagnostic imaging*; D008297:Male; D045423:Microbubbles; D008875:Middle Aged; D013997:Time Factors; D014463:Ultrasonography; D014743:Videotape Recording
chemical_list: D003287:Contrast Media; D002245:Carbon Dioxide