Kevin J. Haworth

Learn More
RATIONALE AND OBJECTIVES Acoustic droplet vaporization (ADV) shows promise for spatial control and acceleration of thermal lesion production. The investigators hypothesized that microbubbles generated by ADV could enhance high-intensity focused ultrasound (HIFU) thermal ablation by controlling and increasing local energy absorption. MATERIALS AND METHODS(More)
The vaporization of a superheated droplet emulsion into gas bubbles using ultrasound--termed acoustic droplet vaporization (ADV)--has potential therapeutic applications in embolotherapy and drug delivery. The optimization of ADV for therapeutic applications can be enhanced by understanding the physical mechanisms underlying ADV, which are currently not(More)
Acoustic droplet vaporization (ADV) shows promise for spatially and temporally targeted tissue occlusion. In this study, substantial tissue occlusion was achieved in operatively exposed and transcutaneous canine kidneys by generating ADV gas bubbles in the renal arteries or segmental arteries. Fifteen canines were anesthetized, among which 10 underwent(More)
Ultrasound-mediated delivery systems have mainly focused on microbubble contrast agents as carriers of drugs or genetic material. This study uses micron-sized, perfluoropentane (PFP) emulsions as carriers of chlorambucil (CHL), a lipophilic chemotherapeutic. The release of CHL is achieved via acoustic droplet vaporization (ADV), whereby the superheated(More)
Ultrasound is known to enhance recombinant tissue plasminogen activator (rt-PA) thrombolysis. In this study, occlusive porcine whole blood clots were placed in flowing plasma within living porcine carotid arteries. Ultrasonically induced stable cavitation was investigated as an adjuvant to rt-PA thrombolysis. Aged, retracted clots were exposed to plasma(More)
INTRODUCTION Ultrasound (US) has been developed as both a valuable diagnostic tool and a potent promoter of beneficial tissue bioeffects for the treatment of cardiovascular disease. These effects can be mediated by mechanical oscillations of circulating microbubbles, or US contrast agents, which may also encapsulate and shield a therapeutic agent in the(More)
Ultrasound contrast agents (UCAs) have the potential to nucleate cavitation and promote both beneficial and deleterious bioeffects in vivo. Previous studies have elucidated the pulse-duration-dependent pressure amplitude threshold for rapid loss of echogenicity due to UCA fragmentation. Previous studies have demonstrated that UCA fragmentation was(More)
Previously, passive cavitation imaging has been described in the context of continuous-wave high-intensity focused ultrasound thermal ablation. However, the technique has potential use as a feedback mechanism for pulsed-wave therapies, such as ultrasound-mediated drug delivery. In this paper, results of experiments and simulations are reported to(More)
Passive cavitation imaging provides spatially resolved monitoring of cavitation emissions. However, the diffraction limit of a linear imaging array results in relatively poor range resolution. Poor range resolution has limited prior analyses of the spatial specificity and sensitivity of passive cavitation imaging in predicting thermal lesion formation. In(More)
Echogenic liposomes (ELIP) are multifunctional ultrasound contrast agents (UCAs) with a lipid shell encapsulating both air and an aqueous core. ELIP are being developed for molecular imaging and image-guided therapeutic delivery. Stability of the echogenicity of ELIP in physiologic conditions is crucial to their successful translation to clinical use. In(More)