About Careers Internship MedBlog Contact us
Medindia LOGIN REGISTER
Advertisement

Using Gas-Filled Microbubbles Could Help Focus Light Inside the Body

by Dr. Trupti Shirole on December 6, 2015 at 1:51 PM
Font : A-A+

 Using Gas-Filled Microbubbles Could Help Focus Light Inside the Body

The primary challenge with focusing light inside the body is that biological tissue is optically opaque. Unlike transparent glass, the cells and proteins that make up tissue scatter and absorb light. A new technique developed at Caltech uses gas-filled microbubbles for focusing light inside tissue. This technique could one day provide doctors with a minimally invasive way of destroying tumors with lasers, and lead to improved diagnostic medical imaging.

Changhuei Yang, professor of electrical engineering, bioengineering, and medical engineering, said, "Our tissues behave very much like dense fog as far as light is concerned. Just like we cannot focus a car's headlight through fog, scientists have always had difficulty focusing light through tissues."

Advertisement


To get around this problem, Yang and his team turned to microbubbles, commonly used in medicine to enhance contrast in ultrasound imaging.

The gas-filled microbubbles are encapsulated by thin protein shells and have an acoustic refractive index - a property that affects how sound waves propagate through a medium - different from that of living tissue. As a result, they respond differently to sound waves.
Advertisement

Haowen Ruan, a postdoctoral scholar in Yang's lab, said, "You can use ultrasound to make microbubbles rapidly contract and expand, and this vibration helps distinguish them from surrounding tissue because it causes them to reflect sound waves more effectively than biological tissue."

In addition, the optical refractive index of microbubbles is not the same as that of biological tissue. The optical refractive index is a measure of how much light rays bend when transitioning from one medium (a liquid, for example) to another (a gas).

Yang, Ruan, and graduate student Mooseok Jang developed a novel technique called time-reversed ultrasound microbubble encoded (TRUME) optical focusing that utilizes the mismatch between the acoustic and optical refractive indexes of microbubbles and tissue to focus light inside the body. First, microbubbles injected into tissue are ruptured with ultrasound waves. By measuring the difference in light transmission before and after such an event, the Caltech researchers can modify the wavefront of a laser beam so that it is focuses on the original locations of the microbubbles. Yang explains, "The result is as if you're searching for someone in a dark field, and suddenly the person lets off a flare. For a brief moment, the person is illuminated and you can home in on their location."

In a new study, published online in Nature Communications, the team showed that their TRUME technique could be used as an effective 'guidestar' to focus laser beams on specific locations in a biological tissue. A single, well-placed microbubble was enough to successfully focus the laser; multiple popping bubbles located within the general vicinity of a target functioned as a map for the light.

Yang said, "Each popping event serves as a road map for the twisting light trajectories through the tissue. We can use that road map to shape light in such a way that it will converge where the bubbles burst."

If TRUME is shown to work effectively inside living tissue - without, for example, any negative effects from the bursting microbubbles - it could enable a range of research and medical applications. For example, by combining the microbubbles with an antibody probe engineered to seek out biomarkers associated with cancer, doctors could target and then destroy tumors deep inside the body or detect malignant growths much sooner.

Yang said, "Ultrasound and X-ray techniques can only detect cancer after it forms a mass. But with optical focusing, you could catch cancerous cells while they are undergoing biochemical changes but before they undergo morphological changes."

The technique could take the place of other of diagnostic screening methods. For instance, it could be used to measure the concentrations of a protein called bilirubin in infants to determine their risk for jaundice. Ruan said, "Currently, this procedure requires a blood draw, but with TRUME, we could shine a light into an infant's body and look for the unique absorption signature of the bilirubin molecule."

Yang said, "In combination with existing techniques that allow scientists to activate individual neurons in lab animals using light, TRUME could help neuroscientists better understand how the brain works. Currently, neuroscientists are confined to superficial layers of the brain. But our method of optical focusing could allow for a minimally invasive way of probing deeper regions of the brain."

Source: Eurekalert
Advertisement

Advertisement
News A-Z
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
What's New on Medindia
Alarming Cesarean Section Trends in India - Convenience or Compulsion of Corporate Healthcare
Quiz on Low-Calorie Diet for Diabetes
World Heart Day in 2022- Use Heart for Every Heart
View all
News Archive
Date
Category
Advertisement
News Category

Medindia Newsletters Subscribe to our Free Newsletters!
Terms & Conditions and Privacy Policy.

More News on:
Healthy Living 

Most Popular on Medindia

Hearing Loss Calculator Drug Interaction Checker Sanatogen Diaphragmatic Hernia Noscaphene (Noscapine) A-Z Drug Brands in India Find a Doctor Selfie Addiction Calculator How to Reduce School Bag Weight - Simple Tips Pregnancy Confirmation Calculator
This site uses cookies to deliver our services. By using our site, you acknowledge that you have read and understand our Cookie Policy, Privacy Policy, and our Terms of Use
×

Using Gas-Filled Microbubbles Could Help Focus Light Inside the Body Personalised Printable Document (PDF)

Please complete this form and we'll send you a personalised information that is requested

You may use this for your own reference or forward it to your friends.

Please use the information prudently. If you are not a medical doctor please remember to consult your healthcare provider as this information is not a substitute for professional advice.

Name *

Email Address *

Country *

Areas of Interests