title: Renal perfusion imaging using contrast-enhanced phase-inversion ultrasound.
abstract: OBJECTIVE
  We evaluated different techniques of contrast-enhanced phase-inversion ultrasound to visualize renal perfusion in native kidneys and kidney transplants.
  
  
  METHODS
  Contrast-enhanced phase inversion ultrasound with different levels of mechanical index and frame rate was performed in 20 kidneys of 13 healthy volunteers. In addition, five dysfunctioning kidneys of patients with chronic renal failure, five functionally intact kidney transplants, three kidney transplants with compensated renal failure, and two kidney transplants with acute rejection were studied. Analysis using a software algorithm for time-resolved perfusion imaging was compared to single-image analysis performed by three independent radiologists.
  
  
  RESULTS
  Optimal depiction of renal perfusion was achieved only by using a mechanical index, which was high enough to destroy the microbubbles of the contrast agent (burst imaging) combined with a low frame rate (0.5 images/second). Renal cortex and medulla showed a homogeneous enhancement in kidneys of healthy volunteers and functionally intact renal transplants. Dysfunctioning kidneys of patients with chronic renal failure as well as kidney transplants with compensated renal failure or acute rejection showed a significantly reduced level of enhancement. Computer-assisted time-resolved perfusion analysis was not superior to single-image analysis.
  
  
  CONCLUSIONS
  Renal perfusion patterns of normal and abnormal tissue can be visualized using contrast-enhanced phase-inversion ultrasound imaging.
authors.affiliation: Department of Neuroradiology, University of Munich, Germany. martin.wiesmann@med.uni-muenchen.de
authors.forename: M
authors.initials: M
authors.lastname: Wiesmann
authors.forename: C U
authors.initials: CU
authors.lastname: Bergmann-Köster
authors.forename: B
authors.initials: B
authors.lastname: Kreft
authors.forename: M
authors.initials: M
authors.lastname: Stöckelhuber
authors.forename: H B
authors.initials: HB
authors.lastname: Gehl
authors.forename: B M
authors.initials: BM
authors.lastname: Stöckelhuber
mesh_terms: D000328:Adult; D003287:Contrast Media; D005260:Female; D006084:Graft Rejection / Q000000981:diagnostic imaging; D006801:Humans; D007668:Kidney / Q000000981:diagnostic imaging*; D007672:Kidney Cortex / Q000000981:diagnostic imaging; D007676:Kidney Failure, Chronic / Q000000981:diagnostic imaging; D007679:Kidney Medulla / Q000000981:diagnostic imaging; D016030:Kidney Transplantation; D008297:Male; D012079:Renal Circulation / Q000502:physiology*; D014463:Ultrasonography / Q000379:methods
chemical_list: D003287:Contrast Media