Published online Jan 28, 2017. doi: 10.4329/wjr.v9.i1.10
Peer-review started: June 15, 2016
First decision: July 29, 2016
Revised: September 18, 2016
Accepted: November 1, 2016
Article in press: November 2, 2016
Published online: January 28, 2017
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.
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.
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.
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.
Core tip: Imaging in patients with renal function impairment (RFI) is challenging because of well-known limitations of conventional color Doppler ultrasound or risks related to the use of contrast media on computed tomography and magnetic resonance imaging. Contrast-enhanced ultrasound is a safer imaging tool in patients with RFI, showing 36% detection rate of renal infarction in patients with acute renal failure of suspicious vascular origin, and the capability of characterizing renal lesions in order to address patients to most proper treatment.