CEUS Evaluation of Hypoxic Ischemic Injury

Contrast-enhanced ultrasonography (CEUS) is a novel imaging technique in which gas-filled microbubbles, smaller than red blood cells, generate increased signal due to the acoustic impedance mismatch. Injection of ultrasound contrast agents into blood increase the echogenicity, allowing enhanced visualization of a blood vessel. Ultrasound contrast agents have been approved for use in Europe for almost two decades. In the case of SonoVue (now called LumasonTM), a second-generation lipid/sulfur hexafluoride US contrast agent (Bracco, Milan, Italy), European Union approved its intravenous use in adults in 2001. The FDA in the United States just recently approved the use of LumasonTM for evaluation of focal hepatic lesions in pediatric population in 2016, and very recently (Jan 2017) approved its use in children for the evaluation of the urinary tract in pediatric patients with known or suspected vesicoureteral reflux. For the remainder of clinical applications, the ultrasound contrast agents are being used off-label in both Europe and the United States. There is already good evidence in the literature that CEUS may be very valuable in children, and that is why it is routinely performed off-label for this purpose in the USA. However, there are ways in which it could be improved, and more studies are needed to definitively establish its diagnostic performance. Sulfur hexafluoride lipid-type A microspheres (LumasonTM, Bracco Inc) is an FDA-approved ultrasound contrast agent. The study duration per subject will be approximately 15 minutes including the time to prepare LumasonTM contrast agent and perform the CEUS, as well as the 60 minute monitoring period after the first and second injection of LumasonTM. CEUS will be performed at the time HII is first suspected or diagnosed and within 24 hours of clinically indicated MRI (which occurs approximately on day 5 of life) for a total of two CEUS exams of 1 hour and 15-minute duration each. Study participation will be complete when the 60 minute monitoring period after the second CEUS is complete. Injection of LumasonTM contrast agent will be performed via the existing peripheral intravenous line or central line using the FDA-recommended dose of up to 0.03 mg/kg. Contrast-agent injection will be performed twice per CEUS scan to ensure image quality and test reproducibility. In the case of more stable patients without an IV line, a peripheral IV line will be started to conduct the investigational CEUS. Two bolus injections will performed to evaluate for dynamic brain perfusion and several 2-minute cine clips as well as static images will be acquired during the exam. Qualitative analysis with visual assessment and quantitative analysis of the acquired CEUS scans will be performed and interpreted by the PI. The scans will be assessed for diagnostic quality of images, artifacts encountered, and the presence of additional contributory diagnostic information.