Ultrasound is one of the most popular diagnostic tools in the medical field due to its non-invasive and non-ionizing nature, but the images can often be blurry, which can prevent a proper diagnosis. George Washington University’s Kausik Sarkar thinks microbubbles may be able to help.
Sarkar, a professor of mechanical and aerospace engineering and head of the Rheology, Biofluids and Ultrasonics Lab in GW’s School of Engineering and Applied Science, is researching injecting microbubbles into a patient’s bloodstream to enhance the contrast of ultrasound images.
The concept is based on sound mechanics; the microbubbles – which are gas bodies coated by a layer of proteins or lipids – reflect a distinct echo that is in sharp contrast to the surrounding tissue, making it easier to distinguish blood from muscles or nerves.
“Bubbles smaller in diameter than the average human injected in the blood stream can significantly improve ultrasound diagnostics, helping in accurate
and early diagnosis of cardiovascular diseases and cancer,” said Sarkar, who began his career studying bubbles in the ocean. "They literally light up the blood vessels."
If medical practitioners have access to cleaner ultrasound images, then they will be able to detect certain diseases sooner and with more accuracy, Sarkar explained, which will hopefully lead to a better recovery prognosis for the patient.
"Bubbles can be used to noninvasively estimate the local blood pressure, which in turn provides important information regarding the functional integrity of many organs," he said. "Doctors can use this information to diagnose and monitor many diseases, such as defective heart valves, malignant tumors, and portal hypertension."
Sarkar is working in collaboration with medical researchers from Thomas Jefferson University in Philadelphia. In September, the team received a grant from the National Institutes of Health in the amount of $2.4 million, $973,560 of which will go to GW.
In addition to improving ultrasound images, microbubbles can also be used for targeted drug delivery. Currently, certain drugs such as chemotherapy drugs are injected into the bloodstream and attack every cell in the body, including healthy cells, which can result in negative side effects such as hair loss and nausea.
Sarkar is collaborating with medical researchers from North Dakota State University to design a type of ultrasound reflecting nanometer-sized particles that will preserve and contain medications until they reach the sick cells, at which point doctors can use sound to disintegrate the microbubbles, thereby distributing the medication only to the area that needs it.
They are currently collaborating on a project funded by an NIH grant that was initially issued in 2015 and renewed in 2020 for a total amount of $1.2 million, $409,469 of which will go to GW.
"Key objectives of modern health care are early and accurate diagnosis of a disease and quick remediation with minimal side effects. The goal of our lab is to facilitate these objectives with the use of ultrasound and micro- and nano-particles," Sarkar said.
"Imagine a tiny bubble or particle that can be inserted into a human body and delivered to a specific target to provide both precise diagnosis of a cancerous tumor and intelligent drug delivery to combat that tumor," he continued. "Our collaborator, Dr. Mallik, designed them for targeted attachment to cancerous tumors and plaques, and we have shown that by encapsulating gas, we can make them responsive to ultrasound."