title: Bolus versus continuous infusion of microbubble contrast agent for liver ultrasound by using an automatic power injector in humans: A pilot study.
abstract: OBJECTIVE
  To evaluate the feasibility of using continuous infusion, in comparison with bolus injection, of a sulfur hexafluoride-microbubble contrast agent to prolong the duration of hepatic parenchymal enhancement in humans during sonographic examination.
  
  
  METHODS
  This pilot study was approved by our institution's ethics committee. Ten patients (5 men and 5 women; mean age ± SD, 65 ± 10 years) each received two injections: a bolus injection (2 ml/s) and then continuous infusion (0.5 ml/min) of the contrast agent by using an automatic injector. Acquired cine clips were transferred to a personal computer, and the video intensity was quantified by dedicated software.
  
  
  RESULTS
  From the time of the first microbubble visualization in the scanning plane, maximal enhancement was reached in 6.3 ± 0.94 seconds after bolus injection and in 13.9 ± 1.44 seconds during continuous infusion (p = 0.002, Wilcoxon's test for paired data). Compared with bolus injection, continuous infusion prolonged the duration of contrast enhancement (4.3 minutes ± 42 seconds versus 7.3 minutes ± 40 seconds; p = 0.002), although no statistically significant difference in maximal enhancement was observed (45 ± 18% for bolus injection and 39 ± 6% for continuous infusion; p = 0.62).
  
  
  CONCLUSIONS
  Continuous infusion of sulfur hexafluoride-filled microbubbles via an automatic power injector prolongs hepatic contrast enhancement without significantly modifying the maximal enhancement over that at baseline. These data, coming from a pilot study, can be used to design a larger study with adequate statistical power.
authors: Department of Radiology, Cattinara Hospital, University of Trieste, Strada di Fiume 447, Trieste, Italy, 34149.
authors: Emilio
authors: E
authors: Quaia
authors: Department of Radiology, Cattinara Hospital, University of Trieste, Strada di Fiume 447, Trieste, Italy, 34149.
authors: Antonio Giulio
authors: AG
authors: Gennari
authors: Department of Radiology, Cattinara Hospital, University of Trieste, Strada di Fiume 447, Trieste, Italy, 34149.
authors: Roberta
authors: R
authors: Angileri
authors: Department of Radiology, Cattinara Hospital, University of Trieste, Strada di Fiume 447, Trieste, Italy, 34149.
authors: Maria Assunta
authors: MA
authors: Cova
mesh_terms: D000368:Aged; D003287:Contrast Media / Q000008:administration & dosage*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007275:Injections, Intravenous / Q000295:instrumentation / Q000379:methods; D008099:Liver / Q000000981:diagnostic imaging*; D008297:Male; D045423:Microbubbles; D010743:Phospholipids / Q000008:administration & dosage*; D010865:Pilot Projects; D013459:Sulfur Hexafluoride / Q000008:administration & dosage*; D014463:Ultrasonography
chemical_list: D003287:Contrast Media; D010743:Phospholipids; C420843:contrast agent BR1; D013459:Sulfur Hexafluoride
keywords: automatic injector; continuous infusion; contrast agent; liver; microbubble; ultrasonography