[Molecular ultrasound imaging: Clinical applications]

[Ultrasound diagnostics of extracranial cerebral arteries]

Color-coded duplex sonography (CCDS) remains the primary angiological method for most clinical cerebrovascular problems. The application of ultrasound is a non-invasive, cost-effective and arbitrarily repeatable examination technique. Simultaneous acquisition of morphologic B‑mode images and hemodynamic parameters with high temporal and spatial resolution is unequalled by any other neurovascular imaging modality. The correct and reproducible use of CCDS requires knowledge of technical details and adequate examination techniques. Its multiparametric approach uses main and additional criteria to detect and precisely quantify clinically highly relevant stenosis of the proximal internal carotid artery. Quantification of vertebral artery stenosis is performed semiquantitatively due to the generally less reliable sonographic approach. The use of CCDS plays an essential role in supporting endovascular and operative procedures as well as in monitoring hemodynamically relevant dissections.

Intracellular delivery and ultrasonic activation of folate receptor-targeted phase-change contrast agents in breast cancer cells in vitro

Breast cancer is a diverse and complex disease that remains one of the leading causes of death among women. Novel, outside-of-the-box imaging and treatment methods are needed to supplement currently available technologies. In this study, we present evidence for the intracellular delivery and ultrasound-stimulated activation of folate receptor (FR)-targeted phase-change contrast agents (PCCAs) in MDA-MB-231 and MCF-7 breast cancer cells in vitro. PCCAs are lipid-coated, perfluorocarbon-filled particles formulated as nanoscale liquid droplets capable of vaporization into gaseous microbubbles for imaging or therapy. Cells were incubated with 1:1 decafluorobutane (DFB)/octafluoropropane (OFP) PCCAs for 1h, imaged via confocal microscopy, exposed to ultrasound (9MHz, MI=1.0 or 1.5), and imaged again after insonation. FR-targeted PCCAs were observed intracellularly in both cell lines, but uptake was significantly greater (p<0.001) in MDA-MB-231 cells (93.0% internalization at MI=1.0, 79.5% at MI=1.5) than MCF-7 cells (42.4% internalization at MI=1.0, 35.7% at MI=1.5). Folate incorporation increased the frequency of intracellular PCCA detection 45-fold for MDA-MB-231 cells and 7-fold for MCF-7 cells, relative to untargeted PCCAs. Intracellularly activated PCCAs ranged from 500nm to 6μm (IQR=800nm-1.5μm) with a mean diameter of 1.15±0.59 (SD) microns. The work presented herein demonstrates the feasibility of PCCA intracellular delivery and activation using breast cancer cells, illuminating a new platform toward intracellular imaging or therapeutic delivery with ultrasound.