title: Impact of contrast-enhanced ultrasound in patients with renal function impairment.
abstract: OBJECTIVE
  To investigate the role of contrast enhanced ultrasound (CEUS) in evaluating patients with renal function impairment (RFI) showing: (1) acute renal failure (ARF) of suspicious vascular origin; or (2) suspicious renal lesions.
  
  
  METHODS
  We retrospectively evaluated patients addressed to CEUS over an eight years period to rule-out vascular causes of ARF (first group of 50 subjects) or assess previously found suspicious renal lesions (second group of 41 subjects with acute or chronic RFI). After preliminary grey-scale and color Doppler investigation, each kidney was investigated individually with CEUS, using 1.2-2.4 mL of a sulfur hexafluoride-filled microbubble contrast agent. Image analysis was performed in consensus by two readers who reviewed digital clips of CEUS. We calculated the detection rate of vascular abnormalities in the first group and performed descriptive statistics of imaging findings for the second group.
  
  
  RESULTS
  In the first group, CEUS detected renal infarction or cortical ischemia in 18/50 patients (36%; 95%CI: 23.3-50.9) and 1/50 patients (2%; 95%CI: 0.1-12), respectively. The detection rate of infarction was significantly higher (P= 0.0002; McNemar test) compared to color Doppler ultrasonography (10%). No vascular causes of ARF were identified in the remaining 31/50 patients (62%). In the second group, CEUS detected 41 lesions on 39 patients, allowing differentiation between solid lesions (21/41; 51.2%) vs complex cysts (20/41; 48.8%), and properly addressing 15/39 patients to intervention when feasible based on clinical conditions (surgery and cryoablation in 13 and 2 cases, respectively). Cysts were categorized Bosniak II, IIF, III and IV in 8, 5, 4 and 3 cases, respectively. In the remaining two patients, CEUS found 1 pseudolesion and 1 subcapsular hematoma.
  
  
  CONCLUSIONS
  CEUS showed high detection rate of renal perfusion abnormalities in patients with ARF, influencing the management of patients with acute or chronic RFI and renal masses throughout their proper characterization.
authors.affiliation: Rossano Girometti, Institute of Diagnostic Radiology, Department of Medical and Biological Sciences, University of Udine, University Hospital "S. Maria della Misericordia", 33100 Udine, Italy.
authors.forename: Rossano
authors.initials: R
authors.lastname: Girometti
authors.affiliation: Rossano Girometti, Institute of Diagnostic Radiology, Department of Medical and Biological Sciences, University of Udine, University Hospital "S. Maria della Misericordia", 33100 Udine, Italy.
authors.forename: Tiziano
authors.initials: T
authors.lastname: Stocca
authors.affiliation: Rossano Girometti, Institute of Diagnostic Radiology, Department of Medical and Biological Sciences, University of Udine, University Hospital "S. Maria della Misericordia", 33100 Udine, Italy.
authors.forename: Elena
authors.initials: E
authors.lastname: Serena
authors.affiliation: Rossano Girometti, Institute of Diagnostic Radiology, Department of Medical and Biological Sciences, University of Udine, University Hospital "S. Maria della Misericordia", 33100 Udine, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Granata
authors.affiliation: Rossano Girometti, Institute of Diagnostic Radiology, Department of Medical and Biological Sciences, University of Udine, University Hospital "S. Maria della Misericordia", 33100 Udine, Italy.
authors.forename: Michele
authors.initials: M
authors.lastname: Bertolotto
keywords: Acute renal failure; Bosniak classification; Contrast-enhanced ultrasonography; Renal cysts; Renal function impairment; Renal infarction; Renal lesions