Ultrasonic imaging is becoming the most popular medical imaging modality,owing to the low price per examination and its safety.However,blood is a poor scatterer of ultrasound waves at clinical diagnostic transmit freq...Ultrasonic imaging is becoming the most popular medical imaging modality,owing to the low price per examination and its safety.However,blood is a poor scatterer of ultrasound waves at clinical diagnostic transmit frequencies.For perfusion imaging,markers have been designed to enhance the contrast in B-mode imaging.These so-called ultrasound contrast agents consist of microscopically small gas bubbles encapsulated in biodegradable shells.In this review,the physical principles of ultrasound contrast agent microbubble behavior and their adjustment for drug delivery including sonoporation are described.Furthermore,an outline of clinical imaging applications of contrast-enhanced ultrasound is given.It is a challenging task to quantify and predict which bubble phenomenon occurs under which acoustic condition,and how these phenomena may be utilized in ultrasonic imaging.Aided by high-speed photography,our improved understanding of encapsulated microbubble behavior will lead to more sophisticated detection and delivery techniques.More sophisticated methods use quantitative approaches to measure the amount and the time course of bolus or reperfusion curves,and have shown great promise in revealing effective tumor responses to anti-angiogenic drugs in humans before tumor shrinkage occurs.These are beginning to be accepted into clinical practice.In the long term,targeted microbubbles for molecular imaging and eventually for directed anti-tumor therapy are expected to be tested.展开更多
Magnetic microbubbles(MMBs)can be controlled and directed to the target site by a suitable external magnetic field,and thus have potential in therapeutic drug-delivery application.However,few studies focus on their dy...Magnetic microbubbles(MMBs)can be controlled and directed to the target site by a suitable external magnetic field,and thus have potential in therapeutic drug-delivery application.However,few studies focus on their dynamics in blood vessels under the action of magnetic and ultrasonic fields,giving little insight into the mechanism generated in diagnostic and therapeutic applications.In this study,equations of MMBs were established for simulating translation,radial pulsation and the coupled effect of both.Meanwhile,the acoustic streaming and shear stress on the vessel wall were also presented,which are associated with drug release.The results suggest that the magnetic pressure increases the bubble pulsation amplitude,and the translation coupled with pulsation is manipulated by the magnetic force,causing retention in the target area.As the bubbles approach the vessel wall,the acoustic streaming and shear stress increase with magnetic field enhancement.The responses of bubbles to a uniform and a gradient magnetic field were explored in this work.The mathematical models derived in this work could provide theoretical support for experimental phenomena in the literature and also agree with the reported models.展开更多
文摘Ultrasonic imaging is becoming the most popular medical imaging modality,owing to the low price per examination and its safety.However,blood is a poor scatterer of ultrasound waves at clinical diagnostic transmit frequencies.For perfusion imaging,markers have been designed to enhance the contrast in B-mode imaging.These so-called ultrasound contrast agents consist of microscopically small gas bubbles encapsulated in biodegradable shells.In this review,the physical principles of ultrasound contrast agent microbubble behavior and their adjustment for drug delivery including sonoporation are described.Furthermore,an outline of clinical imaging applications of contrast-enhanced ultrasound is given.It is a challenging task to quantify and predict which bubble phenomenon occurs under which acoustic condition,and how these phenomena may be utilized in ultrasonic imaging.Aided by high-speed photography,our improved understanding of encapsulated microbubble behavior will lead to more sophisticated detection and delivery techniques.More sophisticated methods use quantitative approaches to measure the amount and the time course of bolus or reperfusion curves,and have shown great promise in revealing effective tumor responses to anti-angiogenic drugs in humans before tumor shrinkage occurs.These are beginning to be accepted into clinical practice.In the long term,targeted microbubbles for molecular imaging and eventually for directed anti-tumor therapy are expected to be tested.
基金the National Natural Science Foundation of China(Grant Nos.12074238,11974232,and11727813)。
文摘Magnetic microbubbles(MMBs)can be controlled and directed to the target site by a suitable external magnetic field,and thus have potential in therapeutic drug-delivery application.However,few studies focus on their dynamics in blood vessels under the action of magnetic and ultrasonic fields,giving little insight into the mechanism generated in diagnostic and therapeutic applications.In this study,equations of MMBs were established for simulating translation,radial pulsation and the coupled effect of both.Meanwhile,the acoustic streaming and shear stress on the vessel wall were also presented,which are associated with drug release.The results suggest that the magnetic pressure increases the bubble pulsation amplitude,and the translation coupled with pulsation is manipulated by the magnetic force,causing retention in the target area.As the bubbles approach the vessel wall,the acoustic streaming and shear stress increase with magnetic field enhancement.The responses of bubbles to a uniform and a gradient magnetic field were explored in this work.The mathematical models derived in this work could provide theoretical support for experimental phenomena in the literature and also agree with the reported models.
