title: Microbubble Void Imaging: A Non-invasive Technique for Flow Visualisation and Quantification of Mixing in Large Vessels Using Plane Wave Ultrasound and Controlled Microbubble Contrast Agent Destruction.
abstract: There is increasing recognition of the influence of the flow field on the physiology of blood vessels and their development of pathology. Preliminary work is reported on a novel non-invasive technique, microbubble void imaging, which is based on ultrasound and controlled destruction of microbubble contrast agents, permitting flow visualisation and quantification of flow-induced mixing in large vessels. The generation of microbubble voids can be controlled both spatially and temporally using ultrasound parameters within the safety limits. Three different model vessel geometries-straight, planar-curved and helical-with known effects on the flow field and mixing were chosen to evaluate the technique. A high-frame-rate ultrasound system with plane wave transmission was used to acquire the contrast-enhanced ultrasound images, and an entropy measure was calculated to quantify mixing. The experimental results were cross-compared between the different geometries and with computational fluid dynamics. The results indicated that the technique is able to quantify the degree of mixing within the different configurations, with a helical geometry generating the greatest mixing, and a straight geometry, the lowest. There is a high level of concordance between the computational fluid dynamics and experimental results. The technique could also serve as a flow visualisation tool.
authors: Department of Bioengineering, Imperial College London, London, UK.
authors: Chee Hau
authors: CH
authors: Leow
authors: Department of Aeronautics, Imperial College London, London, UK.
authors: Francesco
authors: F
authors: Iori
authors: Imperial College Renal and Transplant Centre, Imperial College Healthcare NHS Trust, London, UK.
authors: Richard
authors: R
authors: Corbett
authors: Imperial College Renal and Transplant Centre, Imperial College Healthcare NHS Trust, London, UK.
authors: Neill
authors: N
authors: Duncan
authors: Department of Bioengineering, Imperial College London, London, UK.
authors: Colin
authors: C
authors: Caro
authors: Department of Aeronautics, Imperial College London, London, UK.
authors: Peter
authors: P
authors: Vincent
authors: Department of Bioengineering, Imperial College London, London, UK. Electronic address: mengxing.tang@imperial.ac.uk.
authors: Meng-Xing
authors: MX
authors: Tang
mesh_terms: D001808:Blood Vessels / Q000000981:diagnostic imaging*; D003287:Contrast Media; D007089:Image Enhancement / Q000379:methods*; D066298:In Vitro Techniques; D045423:Microbubbles; D008962:Models, Theoretical; D019047:Phantoms, Imaging; D014463:Ultrasonography / Q000379:methods*
chemical_list: D003287:Contrast Media
keywords: Contrast-enhanced ultrasound; Flow indicator; High-frame-rate plane wave imaging; Microbubble contrast agents; Microbubble void imaging; Mixing