title: Low mechanical index contrast mode versus high mechanical index contrast mode: which is a more sensitive method for detecting Sonazoid microbubbles in the liver of normal subjects?
abstract: OBJECTIVE
  Using the low mechanical index (MI) contrast mode and the high MI contrast mode of contrast-enhanced ultrasonography, we evaluated which method is more sensitive for detecting Sonazoid microbubbles in the liver of normal subjects.
  
  
  METHODS
  Thirteen normal subjects received an intravenous bolus injection of 0.2 mL of Sonazoid. We defined the intensity difference as the intensity post-injection minus the intensity pre-injection. We evaluated the intensity difference at the portal vein using both the low MI (0.21-0.23) and the high MI (0.7-1.2) at 1 min, at every 10 min between 10 to 60 min, and at every 30 min between 60 to 300 min post-injection. The intensity difference at the liver parenchyma was also evaluated at eight points (1, 10, 30, 60, 120, 180, 240, and 300 min) using the low MI and at three points (1, 10, and 300 min) using the high MI.
  
  
  RESULTS
  The intensity differences at the portal vein measured using high MI were significantly higher than those measured using the low MI at each point between 1 and 240 min (P < 0.01) and at 270 min post-injection (P < 0.05). The intensity differences at the liver parenchyma measured using the high MI were also significantly higher than those measured using the low MI at each time point (P < 0.01).
  
  
  CONCLUSIONS
  Compared with the low MI, the high MI is more sensitive for detecting Sonazoid microbubbles in the liver of normal subjects.
authors.affiliation: Gastroenterological Center, Yokohama City University Medical Center, 4-57 Urafune-cho, Minami-ku, Yokohama, Kanagawa, 232-0024, Japan.
authors.forename: Hiromi
authors.initials: H
authors.lastname: Nihonmatsu
authors.affiliation: Gastroenterological Center, Yokohama City University Medical Center, 4-57 Urafune-cho, Minami-ku, Yokohama, Kanagawa, 232-0024, Japan. kz-numa@urahp.yokohama-cu.ac.jp.
authors.forename: Kazushi
authors.initials: K
authors.lastname: Numata
authors.affiliation: Gastroenterological Center, Yokohama City University Medical Center, 4-57 Urafune-cho, Minami-ku, Yokohama, Kanagawa, 232-0024, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Fukuda
authors.affiliation: Gastroenterological Center, Yokohama City University Medical Center, 4-57 Urafune-cho, Minami-ku, Yokohama, Kanagawa, 232-0024, Japan.
authors.forename: Katsuaki
authors.initials: K
authors.lastname: Tanaka
authors.affiliation: Department of Biostatistics, Yokohama City University Medical Center, Yokohama, Kanagawa, 236-0004, Japan.
authors.forename: Mari
authors.initials: M
authors.lastname: Ooba
authors.affiliation: Division of Gastroenterology, Yokohama City University Graduate School of Medicine, Yokohama, Kanagawa, 232-0024, Japan.
authors.forename: Shin
authors.initials: S
authors.lastname: Maeda
mesh_terms: D000328:Adult; D003287:Contrast Media; D005260:Female; D005290:Ferric Compounds; D006801:Humans; D007501:Iron; D008099:Liver / Q000000981:diagnostic imaging*; D008297:Male; D045423:Microbubbles; D008875:Middle Aged; D015588:Observer Variation; D010087:Oxides; D011169:Portal Vein / Q000000981:diagnostic imaging; D011446:Prospective Studies; D013997:Time Factors; D014463:Ultrasonography / Q000379:methods*
chemical_list: D003287:Contrast Media; D005290:Ferric Compounds; D010087:Oxides; C069727:Sonazoid; D007501:Iron
keywords: Contrast-enhanced ultrasonography; High mechanical index contrast mode; Intensity difference; Low mechanical index contrast mode; Sonazoid microbubbles