March 2014

Human Body 'Fantastic Voyage' Comes To Life
Real-time 3D imaging from within the human body.
Article By Steven R. Rochlin

  Researches at Georgia Tech have invented a new single chip device to provide real-time 3D images from inside the human body. Virtually anyone over the age of 40 remembers the movie Fantastic Voyage, where a submarine and medical researchers are shrunk down to an extremely miniature size to then navigate inside the sub within a human body. Well, we may not need a submarine or fancy technology to shrink it as the great people at Georgia Tech have developed the technology for a catheter-based device that would provide forward-looking, real-time, three-dimensional imaging from inside the heart, coronary arteries and peripheral blood vessels. With its volumetric imaging, the new device could better guide surgeons working in the heart, and potentially allow more of patients’ clogged arteries to be cleared without major surgery.

This single-chip 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 forward-looking images produced by the device would provide significantly more information than existing cross-sectional ultrasound. Researchers have developed and tested a prototype able to provide image data at 60 frames per second, and plan next to conduct animal studies that could lead to commercialization of the device.

The single chip device combines capacitive micro-machined ultrasonic transducer (CMUT) arrays with front-end CMOS electronics technology to provide three-dimensional 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. They must also be able to operate in blood.

"Our device will allow doctors to see the whole volume that is in front of them within a blood vessel," said F. Levent Degertekin, a professor in the George W. Woodruff School of Mechanical Engineering at the Georgia Institute of Technology. "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. 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."

In addition to Degertekin, the research team included Jennifer Hasler, a professor in the Georgia Tech School of Electrical and Computer Engineering; Mustafa Karaman, a professor at Istanbul Technical University; Coskun Tekes, a postdoctoral fellow in the Woodruff School of Mechanical Engineering; Gokce Gurun and Jaime Zahorian, recent graduates of Georgia Tech’s School of Electrical and Computer Engineering, and Georgia Tech Ph.D. students Toby Xu and Sarp Satir.