single-chip catheter-based device that would provide forward-looking, real-time, three-dimensional imaging from inside the heart
February 19, 2014

Tiny Device Gives Real-Time, 3D Imaging From Inside The Heart, Clogged Arteries

redOrbit Staff & Wire Reports - Your Universe Online

Engineers at Georgia Institute of Technology have developed a new catheter-based device that provides real-time, 3D imaging from inside the heart and arteries.

The breakthrough device could someday assist cardiac surgeons working in the heart, and potentially allow more of a patient’s clogged arteries to be cleared without major surgery, the researchers said.

The tiny device integrates ultrasound transducers with processing electronics on a single 1.4 millimeter silicon chip. On-chip processing of signals allows data from more than a hundred elements on the device to be transmitted using just 13 tiny cables, permitting it to easily travel through circuitous blood vessels. The images produced by the device would deliver dramatically more information than current cross-sectional ultrasound provides.

The researchers have developed and tested a prototype device able to provide image data at 60 frames per second, and plan to conduct animal studies that could lead to commercialization of the device.

"Our device will allow doctors to see the whole volume that is in front of them within a blood vessel," said F. Levent Degertekin, professor of mechanical engineering at Georgia Tech.

"This will give cardiologists the equivalent of a flashlight so they can see blockages ahead of them in occluded arteries. It has the potential for reducing the amount of surgery that must be done to clear these vessels."

"If you're a doctor, you want to see what is going on inside the arteries and inside the heart, but most of the devices being used for this today provide only cross-sectional images," Degertekin said.

“If you have an artery that is totally blocked, for example, you need a system that tells you what's in front of you. You need to see the front, back and sidewalls altogether. That kind of information is basically not available at this time."

The single chip device combines capacitive micromachined ultrasonic transducer (CMUT) arrays with front-end CMOS electronics technology to provide 3D intravascular ultrasound (IVUS) and intracardiac echography (ICE) images. The dual-ring array includes 56 ultrasound transmit elements and 48 receive elements. When assembled, the donut-shaped array is just 1.5 millimeters in diameter, with a 430-micron center hole to accommodate a guide wire.

Power-saving circuitry in the array shuts down sensors when they are not needed, allowing the device to operate with just 20 milliwatts of power, reducing the amount of heat generated inside the body.

The ultrasound transducers operate at a frequency of 20 megahertz (MHz). Imaging devices operating within blood vessels can provide higher resolution images than devices used from outside the body because they can operate at higher frequencies. But operating inside blood vessels requires devices that are small and flexible enough to travel through the circulatory system and to operate in blood.

Achieving that requires a large number of elements to transmit and receive the ultrasound information. But transmitting data from these elements to external processing equipment could require many cable connections, potentially limiting the device's ability to be threaded inside the body.

Degertekin and his team addressed that challenge by miniaturizing the elements and conducting some of the processing on the probe itself, allowing them to obtain what they believe are clinically useful images with just 13 cables.

"You want the most compact and flexible catheter possible," Degertekin said. "We could not do that without integrating the electronics and the imaging array on the same chip."

Based on their prototype, the researchers expect to conduct animal trials to demonstrate the device's potential applications. They ultimately hope to license the technology to an established medical diagnostic firm to conduct the clinical trials necessary to obtain FDA approval.

Degertekin said he hopes to develop a version of the device that could guide interventions in the heart under magnetic resonance imaging (MRI). Additional plans include further reducing the size of the device to place it on a 400-micron diameter guide wire.

Details of the research were published online in the February 2014 issue of the journal IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

Image 2 (below): A single-chip catheter-based device that would provide forward-looking, real-time, three-dimensional imaging from inside the heart, coronary arteries and peripheral blood vessels is shown being tested. Credit: Georgia Tech Photo: Rob Felt