title: Prospective evaluation of vascular complications after liver transplantation: comparison of conventional and microbubble contrast-enhanced US.
abstract: OBJECTIVE
  To prospectively compare diagnostic performance of conventional Doppler ultrasonography (US) and microbubble contrast material-enhanced US for assessment of vascular complications after liver transplantation, with clinical follow-up or angiography as reference standard.
  
  
  METHODS
  This study was approved by institutional review board and was HIPAA compliant. Written informed consent was obtained. Seventy-two patients (49 men, 23 women; average age, 52.3 years) were included in this study. Patients who had undergone liver transplantation underwent conventional color Doppler and contrast-enhanced US of the liver. Quality of hepatic artery (HA) and portal vein (PV) visualization, contrast material arrival time, and time for complete evaluation of vasculature were compared for both techniques. McNemar test was used to compare vascular flow visualization scores; Student t test was used to compare mean study times with both techniques. Patients without HA flow at Doppler US underwent angiography; those with flow were followed up clinically. McNemar test was used to compare sensitivity of both techniques.
  
  
  RESULTS
  Contrast-enhanced US helped significantly improve flow visualization in hepatic vessels (P < .001). Mean contrast material arrival time was 13.7 seconds +/- 3.8 (standard deviation) in proper HA and 20.7 seconds +/- 6.3 in PV. Mean study time decreased from 27.4 minutes +/- 13.9 to 9.3 minutes +/- 4.5 (P < .01). Doppler US failed to depict HA flow in eight patients; contrast-enhanced US showed flow in six and no flow in two of these patients. Follow-up results confirmed contrast-enhanced US findings. Sensitivity, specificity, and accuracy for Doppler US were 91.3%, 100%, and 91.5%, respectively. Sensitivity, specificity, and accuracy of contrast-enhanced US were all 100%. Sensitivity and accuracy values of the two techniques were significantly different (P < .014); there was no significant difference in specificity (P > .99)
  
  
  CONCLUSIONS
  Contrast-enhanced US helped improve flow visualization in the HA and PV, decrease scanning time, and correctly differentiate between thrombosis and a patent artery in patients without HA flow at conventional Doppler US.
authors.affiliation: Department of Radiology, University of Southern California, Keck School of Medicine, USC University Hospital, 1500 San Pablo St, Los Angeles, CA 90033, USA.
authors.forename: Benjamin K
authors.initials: BK
authors.lastname: Hom
authors.forename: Ruchi
authors.initials: R
authors.lastname: Shrestha
authors.forename: Suzanne L
authors.initials: SL
authors.lastname: Palmer
authors.forename: Michael D
authors.initials: MD
authors.lastname: Katz
authors.forename: R Rick
authors.initials: RR
authors.lastname: Selby
authors.forename: Zhanna
authors.initials: Z
authors.lastname: Asatryan
authors.forename: Jabali K
authors.initials: JK
authors.lastname: Wells
authors.forename: Edward G
authors.initials: EG
authors.lastname: Grant
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D008099:Liver / Q000098:blood supply*; D016031:Liver Transplantation; D008297:Male; D045423:Microbubbles; D008875:Middle Aged; D011183:Postoperative Complications; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D014463:Ultrasonography / Q000379:methods*; D018615:Ultrasonography, Doppler, Color; D014652:Vascular Diseases / Q000000981:diagnostic imaging* / Q000209:etiology