Improving sensitivity and imaging depth of ultrasound-switchable fluorescence via an EMCCD-gain-controlled system and a liposome-based contrast agent.

摘要: Background The ultrasound-switchable fluorescence (USF) technique was recently developed to achieve high-resolution imaging in centimeters-deep tissue. This study introduced strategies significantly improve sensitivity and depth using an electron multiplying charge-coupled device (EMCCD) camera-based USF system a newly contrast agent of indocyanine green (ICG)-encapsulated liposomes. For quantitative study, phantom sub-millimeter silicone tube embedded centimeter-thick chicken breast tissue adopted this as model. Methods synthesized ICG-liposome characterized compared with the previously reported ICG-nanogel. exposure EMCCD camera controlled via MATLAB (The MathWorks, Inc. USA), instead external hardware trigger. stability (EM) gain between two trigger modes: mode mode. signal-to-noise ratio (SNR) different EM various thick studied. Results hydrodynamic size ~181 nm. had sharper temperature switching curve better performance than more stable Although, usual, SNR decreased quickly increase thickness, proposed improved by adopting novel controlling gain. Conclusions We successfully imaged inner diameter 0.76 mm outer 1.65 5.5 cm-thick 808 nm excitation light low intensity 28.35 mW/cm2, ICG-liposomes.