Medical Imaging  

A single-chip catheter-based device has been developed by researchers that would provide forward-looking, real-time, three-dimensional imaging from inside the heart, coronary arteries and peripheral blood vessels.

Researchers have developed the technology for a catheter-based device that would provide forward-looking, real-time, 3D 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.

The 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.

“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 were published in the journal 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 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 explained. “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 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.

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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.

Doing that requires a large number of elements to transmit and receive the ultrasound information. 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 collaborators addressed that challenge by miniaturizing the elements and carrying out some of the processing on the probe itself, allowing them to obtain what they believe are clinically-useful images with only 13 cables.

“You want the most compact and flexible catheter possible,” Degertekin explained. “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 expect to license the technology to an established medical diagnostic firm to conduct the clinical trials necessary to obtain FDA approval.

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



SOURCE  Georgia Tech

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 Ethics  

Medical implants, complex interfaces between brain and machine or remotely controlled insects  —recent developments combining machines and organisms have great potentials, but also give rise to major ethical concerns.

They are known from science fiction novels and films – technically modified organisms with extraordinary skills, so-called cyborgs. This name originates from the English term “cybernetic organism”. In fact, cyborgs that combine technical systems with living organisms are already reality.

As Karlsruhe Institute of Technology (KIT) researchers Professor Christof M. Niemeyer and Dr. Stefan Giselbrecht of the Institute for Biological Interfaces 1 (IBG 1) and Dr. Bastian E. Rapp, Institute of Microstructure Technology (IMT), point out that this especially applies to medical implants.

In their review entitled "The Chemistry of Cyborgs -- Interfacing Technical Devices with Organisms," KIT scientists discuss the state of the art of research, opportunities, and risks. The review is published now by the renowned journal Angewandte Chemie International Edition.

In recent years, medical implants based on smart materials that automatically react to changing conditions, computer-supported design and fabrication based on magnetic resonance tomography datasets or surface modifications for improved tissue integration allowed major progress to be achieved. For successful tissue integration and the prevention of inflammation reactions, special surface coatings were developed also by the KIT under e.g. the multidisciplinary Helmholtz program “BioInterfaces”.

Progress in microelectronics and semiconductor technology has been the basis of electronic implants controlling, restoring or improving the functions of the human body, such as cardiac pacemakers, retina implants, hearing implants, or implants for deep brain stimulation in pain or Parkinson therapies. Currently, bioelectronic developments are being combined with robotics systems to design highly complex neuroprostheses.

Cathy Hutchinson has been unable to move her own arms or legs for 15 years. But using the most advanced brain-machine interface ever developed, she can steer a robotic arm towards a bottle, pick it up, and drink her morning coffee.

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Scientists are working on brain-machine interfaces (BMI) for the direct physical contacting of the brain. BMI are used among others to control prostheses and complex movements, such as gripping. Moreover, they are important tools in neurosciences, as they provide insight into the functioning of the brain. Apart from electric signals, substances released by implanted micro- and nanofluidic systems in a spatially or temporarily controlled manner can be used for communication between technical devices and organisms.

BMI are often considered data suppliers. However, they can also be used to feed signals into the brain, which is a highly controversial issue from the ethical point of view. “Implanted BMI that feed signals into nerves, muscles or directly into the brain are already used on a routine basis, e.g. in cardiac pacemakers or implants for deep brain stimulation,” Professor Christof M. Niemeyer, KIT, explains. “But these signals are neither planned to be used nor suited to control the entire organism – brains of most living organisms are far too complex.”

Brains of lower organisms, such as insects, are less complex. As soon as a signal is coupled in, a certain movement program, such as running or flying, is started. So-called biobots, i.e. large insects with implanted electronic and microfluidic control units, are used in a new generation of tools, such as small flying objects for monitoring and rescue missions. In addition, they are applied as model systems in neurosciences in order to understand basic relationships.

Electrically active medical implants that are used for longer terms depend on reliable power supply. Presently, scientists are working on methods to use the patient body’s own thermal, kinetic, electric or chemical energy.

In their review the KIT researchers sum up that developments combining technical devices with organisms have a fascinating potential. They may considerably improve the quality of life of many people in the medical sector in particular. However, ethical and social aspects always have to be taken into account.


SOURCE  KIT

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