The Small Stuff Matters
|Analog Devices has released two new integrated circuits designed to permit smaller devices to process images more quickly and with improved quality compared to predecessors.|
As health care providers become more mobile, they demand that their equipment does as well. Subsequently, manufacturers are constantly challenged to produce equipment that is smaller, faster, and better than that which preceded it. To achieve this, manufacturers need smaller, faster, better components.
Analog Devices, Inc (ADI), Norwood, Mass, is a component supplier delivering those smaller, faster, better components. The company offers analog, mixed-signal, and digital signal processing integrated circuits (IC) to customers who include ultrasound manufacturers. Last year, ADI introduced the AD9271, the first device to integrate a complete octal ultrasound receiver on a single chip. A That chip was followed this year by the AD9272, for use in cart-based systems, and the AD9273, for portable devices.
Users of the ultrasound systems that incorporate these ICs see benefits that include bedside imaging; quicker results; longer battery life; improved reliability; smaller sizes; reduced costs; and improved image quality, with finer resolution, deeper penetration, and the ability to see tissue and blood flow. The smaller form factors and lower costs, in particular, have helped to facilitate use of the devices in nontraditional settings, such as ambulances, field hospitals, clinics, rescue crews, and physician’s offices.
“I think the electronics of an ultrasound system are transparent to radiologists. What they do care about is the fact that these ultrasound systems have gotten much smaller, and even laptop systems are beginning to meet the performance metrics of cart-based systems,” said Scott Pavlik, strategic marketing manager responsible for patient monitoring and medical imaging for the Healthcare segment of ADI.
Pavlik doesn’t credit ICs solely with enabling these smaller, faster, better devices, but the component is a key part of the overall system. “Many other parts were optimized and trunked down by system designers, but the receiver chain is a big piece of the process,” Pavlik said. Other components include the probe or transducer, switches, processing units, video compression, signal control, and power management.
ADI’s new ICs combine a number of individual components onto one chip, minimizing the use of external components as well as power and space. Each circuit of the eight-channel array is comprised of a low-noise amplifier, a variable-gain amplifier, an anti-aliasing filter, and a 12-bit analog-to-digital converter. Pin compatibility maximizes the integratability of the solution.
“The AD927x family offers a complete, optimized, flexible receiver solution for both cart-based and battery-powered designs,” said Pat O’Doherty, health care segment director for ADI, in a press release.
Both the AD9272 and AD9273 feature a variable gain range of up to 42 dB and a selection of antialiasing filter options. Designers can customize the noise and power performance for any given imaging mode, probe, or power requirement using the serial port interface (SPI) of both the AD9272 and AD9273. They can modify SPI registers to optimize noise performance or battery life.
“We took what we learned from customers of the AD9271 and optimized it for performance, resulting in the AD9272, and then for power reduction, producing the AD9273,” Pavlik said.
The cart-based AD9272 offers low input referred noise (when operating under real-world conditions) and improved input dynamic range when compared to market predecessors, according to the company.
The AD9273 features power dissipation of less than 100 mW per channel @ 12 bits and 40 MSPS, also an improvement over current market offerings, according to Pavlik. This feature extends the battery life of the ultrasound device, and the resulting capabilities “facilitate portable systems that can be brought bedside, available in emergency equipment like ambulances, or used in doctor’s’ offices,” Pavlik said.
The company notes that hospitals, medical clinics, and mobile emergency units are increasingly relying on high-performance and portable ultrasound equipment for routine, preventive, and acute medical care. The demand challenges designers to balance image quality and power efficiency.
Smaller, faster, better components help to meet that demand.
FUSF Organizes First Symposium on MRgFUS
|Neal F. Kassell, MD, professor of neurosurgery, University of Virginia, and chairman of the FUSF Board of Directors|
The Focused Ultrasound Surgery Foundation (FUSF) in Charlottesville, Va, has a vision. That vision—as shared by Ferenc Jolesz, MD, professor of radiology at Harvard Medical School in Boston, and director of the Image Guided Therapy Program at Brigham and Women’s Hospital, also in Boston—is to see MR-guided focused ultrasound, or MRgFUS, replace many surgical procedures and, in some cases, eliminate the need for ionizing radiation. The foundation was founded in 2006 to speed that adoption.
To further its role as catalyst, the foundation planned a symposium to explore the possibilities and implications of this goal, with topics covering research, clinical management, and socioeconomic perspectives. In October, the first such event—the MRgFUS 2008 International Symposium—was held in Washington, DC.
Roughly 300 experts, both researchers and clinicians, gathered to discuss MRgFUS and its clinical applications, its use in targeted drug delivery, sonothrombolysis, reimbursement, training and credentialing, and adoption acceleration. Symposium speakers highlighted developments in the treatment of cancer (particularly cancers of the prostate, breast, liver, and bones), neurological disorders, and uterine fibroids.
The symposium opened with the David B. and Diane Heller Lecture presented by Jolesz and which looked at the history, present, and future of MRgFUS. Jolesz noted that the integration of MR with focused ultrasound has been a major step in the development of the modality and has allowed accurate targeting; high sensitivity; safe, therapeutically effective dosing; and temperature monitoring. As a result of the benefits, applications are continually expanding.
Presenters looked at clinical applications, such as uterine fibroid treatment, as well as applications in earlier stages of development. A number of presentations examined results obtained in animal studies, including mice, rats, pigs, and dogs.
For instance, Harnof and team examined the proof of concept for trans-skull clot lysis using porcine blood. Primary findings indicated that high-intensity focused ultrasound has the potential to be a noninvasive treatment modality for use in clinical situations, such as intracerebral hemorrhage. Half of the 18 “sonications resulted in clot liquefaction at the target without thermal effect.”
Dotan and colleagues studied the feasibility of using MRgFUS for thermal ablation in the prostate of dogs. They concluded that the modality is a “precise and effective means to destroy anatomically predefined prostate tissues by thermocoagulation with minimal associated edema or damage to adjacent structures, with the correct treatment parameters.”
New Clinical Applications
A number of studies considered the usefulness of MRgFUS as a drug delivery system. Schroeder, Yechezkel, and Kost found that “localized drug release by ultrasound is a novel and effective modality which can address a wide range of clinical needs.”
The team studied the “localized release of drugs from stealth liposomes in tumors using low-frequency ultrasound” in tumor-bearing animals. Other groups presented drug delivery studies analyzing high-intensity focused ultrasound, pulsed high-intensity focused ultrasound, liquid perfluorocarbon droplets, liposome microbubbles pendants, and the ExAblate from InSightec Inc, Dallas.
H?lscher and team, who gathered data for two objectives, also studied the ExAblate system: to test whether transcranial sonothrombolysis could be achieved using focused ultrasound and whether defocusing occurs during trans-skull insonation. They concluded the answer to the first question was a yes (effectively in the absence of tPA) and to the second a no (“transcranial sonothrombolysis using focused ultrasound can be achieved without correcting for bone”).
New Knowledge About Old Apps
Though innovation represented a key segment of the symposium, studies of existing procedures were also presented, with uterine fibroids dominating 2 hours of the program. Topics looked at the procedure and the devices, such as an MR-guided high-intensity focused ultrasound system from China’s Haifu Technology Co and Siemens Healthcare, Malvern, Pa.
In another study, Hesley et al followed up patients who had been treated with MRgFUS after its approval by the FDA in 2004. The team found a low alternative treatment rate similar to the range reports for myomectomy and uterine artery embolization.
Though the modality has received approval for uterine fibroid treatment, it is not recommended in patients who wish to maintain fertility. Rabinovich considered this contraindication and found support for reevaluation of the “self-imposed limitation.” His research suggests that women treated with MRgFUS for significant uterine fibroids can successfully become pregnant and deliver healthy babies at full term.
InSightec notes that more than 4,000 women have had their uterine fibroids treated with ExAblate’s MRgFUS, and that number is expected to grow. As the applications for this newer modality increase, a growing number of patients of all demographics may undergo MRgFUS, particularly if the FUSF has its way.
“The major advantage of MRI guidance over other imaging modalities is its ability to achieve accurate targeting while avoiding thermal injury of normal tissues. Over the next decade, MRgFUS will almost certainly replace several invasive open surgeries and will likely supplant minimally invasive approaches as the preferred treatment approach,” Jolesz writes.