Imaging chip offers 'flashlight' to blockage-seeking cardiologists

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.

The device integrates ultrasound transducers with processing electronics on a single 1.4mm silicon chip. On-chip processing of signals allows data from more than a hundred elements on the device to be transmitted using 13 cables, allowing it to easily travel through circuitous blood vessels. It is claimed 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 commercialisation 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, 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.’

Details of the research have been published in IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control. Research leading to the device development was supported by the National Institute of Biomedical Imaging and Bioengineering (NIBIB), part of the US National Institutes of Health.

‘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 in a statement. ‘If you have an artery that is totally blocked, for example, you need a system that tells you what’s in front of you. That kind of information is basically not available at this time.’

The single chip device is said to combine capacitive micromachined 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 1.5mm in diameter, with a 430-micron centre 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 20mW of power, reducing the amount of heat generated inside the body. The ultrasound transducers themselves operate at a frequency of 20MHz.

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