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News & Notes
Acoustic Droplet Vaporization Lab Celebrates A Milestone Year
By Nikolas Charles
Spring 2026
It’s been nearly two years since the group of dedicated U-M ultrasound scientists studying Acoustic Droplet Vaporization (ADV) gathered together to commemorate their work. The quarter of a century anniversary event that took place on campus on July 12th 2024 gave everyone involved the chance to look back at their accomplishments and forward to future goals.
“Its evolving research is amazing to watch,” says Oliver Kripfgans, PhD, one of the early developers of the technique. “The people involved in the research and development of ADV are a true blessing.” He delivered a heartfelt speech to the gathering of 60 current and former lab members, alumni and colleagues. Other speakers included key radiology faculty members and mentors including Drs. Paul Carson, Douglas Miller, Brian Fowlkes, and Mario Fabiilli.
One of the mutual goals of the research group is to share this technology with other medical schools, health systems and laboratories through its peer reviewed publications and national radiology organizations.
“ADV can be used in many different types of applications,” says Mario Fabiilli, PhD, Associate Professor of Radiology and Biomedical Engineering. For those less familiar with this technique, “ADV is the process by which Ultrasound (US) is used to turn perfluorocarbon liquid droplets into gas bubbles.” Once injected, a transducer device that converts energy from one form to another, is used to turn the bioinert synthetic liquid into microbubbles, the size of red blood cells.
“Because they’re so small, they don’t harm the tissue,” says Dr. Kripfgans. “We wanted to make vascular bubbles inside the veins and arteries of the body. Also known as ultrasound contrast agents, these bubbles circulate through the system. They’re called transpulmonary bubbles because they pass through the capillaries. Rather than making bubbles out of nothing, which is called cavitation, we’re making bubbles out of droplets,” he says, explaining that bubbles are gas filled and droplets are fluid filled. With the ADV process, US converts the perfluorocarbon droplet into a bubble. It then vaporizes and changes from a liquid state to a gas state.”
“The reason the tiny droplets are vaporized into gas bubbles is because they are triggered by acoustic pulses,” adds Dr. Fowlkes, who directs research in ultrasound for diagnostic and therapeutic applications. As two of the early developers of the process, Kripfgans and Fowlkes, Professors of Radiology and Biomedical Engineering, determined that ADV could have valuable clinical technique.
When Dr. Kripfgans joined U-M as a graduate student in 1996 he began understanding the physics associated with these vaporization events, such as: how did the bubble vaporize? And how rapidly did it vaporize? “He began doing high-speed photography of vaporization events and to learn how the acoustic field in and around these droplets were affecting the vaporization process,” shared Dr. Fowlkes.
Moving from bench to pre-clinical research, they discovered that ADV could be utilized as a drug delivery system, it could also occlude blood flow to the kidneys, which would allow clinicians to starve cancer cells. “Those droplet triggers are a means of therapeutically controlling how blood flows into different tissues and even in the brain,” says Dr. Fowlkes. Before the ADV process, this type of intervention could only be accomplished surgically, now it could be done with this minimally invasive technique or transcutaneously.
Along with Dr. Fabiilli, the ongoing ADV research at U-M is being conducted in the Ultrasonic Cavitation and Calibration Lab by Mitra Aliabouzar, PhD, Research Assistant Professor. “I use ADV as a tool to characterize tissue properties,” says Dr. Aliabouzar, whose research specializes in integrating acoustics, mechanics, and material science to advance the biomedical applications of ultrasound. “ADV is also used to estimate the age of a blood clot and how soft or stiff it is which helps with treatment options. Detecting changes to the tissue can lead to early detection in diseases like cancer.”
While much of Dr. Aliabouzar’s ADV research centers around its potential diagnostic usages, Dr. Fabiilli focuses on its strengths for medical therapy. For one vaporization process, he loads drugs inside droplets, which allows him to control the release of drugs. “Another application that is very unique is rather than injecting droplets into the bloodstream, we can load them into implants that go into the body.” This process was recently used for an NIH funded study to develop a treatment for peripheral artery disease. Additional applications include regrowing blood vessels and bone as well as using ADV as a process for treating type-one diabetes.
After more than 25 years of research, the ADV lab scientists look forward to the day that this unique process can be used to benefit the lives of patients.