Handheld ultrasound systems advance in power and performance

Manufacturers continue to close the performance gap between handheld ultrasound systems and their more expensive cart-based competitors. Underlying this development are transducer improvements and unique imaging enhancements, even as the engineers of these units advance their strong suit - portability. Zonare Medical Systems and SonoSite exemplify this progress.

Over the past two years, Zonare has drawn attention with its distinctive z.one ultrasound platform, billed as the first convertible ultrasound system. Users can instantly convert z.one from a full-featured, cart-based unit into a premium handheld system. At the 2005 RSNA meeting, Zonare improved on the product with several key upgrades, including two new transducers, two new calculation packages, and a program that automatically recognizes and adjusts for differences in body sound propagation.

Its new P4-1 and P10-4 transducers expand the convertible z.one's imaging capabilities and applications, whether used as a cart-based or compact system, according to the company. The small size of the P4-1, designed for abdominal and ob/gyn sonography, is particularly helpful when acoustic access is difficult. Nine frequencies make it extremely flexible. Moreover, the transducer penetrates up to 30 cm, a capability growing more important as the U.S. population grows wider.

"Customers told us they need more firepower in their transducers, especially when going portable with the convertible system, because that's when they take the equipment right down to the most difficult-to-image patients," said Lars Shaw, Zonare's vice president of marketing. "We responded with this phased-array (4 MHz) transducer, which advances the system's application power."

The P10-4 is designed for neonatal, infant, and pediatric imaging. Its ergonomic design provides a comfortable grip for scanning through isolettes and very small acoustic windows. The probe offers up to seven different frequencies, including harmonic imaging at 8 MHz, two color Doppler frequencies, and three B-mode frequencies.

Zonare's new sound speed compensation program further boosts the power of the unit, automatically adjusting sound speed based on differences in patient body habitus. This optimizes clinical images, according to Shaw.

"It analyzes raw ultrasound echo data and determines the speed of sound as it travels through body," he said. "Ultrasound machines typically assume that speed travels at 1540 meters per second. But that speed isn't true all the time. For instance, through fat is a slower speed, while through muscle is faster. Machines don't assume that."

Shaw said the program determines the speed of sound in the different tissues and then compensates the images appropriately. This capability, which is unique to Zonare, is made possible by the company's patented Zone Sonography technology.

The new calculation packages address abdominal and venous imaging. They enable sonographers to use a protocol checklist with reports that include organ sizes, Doppler results, and a section for medical notes or comments.

The company that pioneered advanced handheld ultrasound, SonoSite, showcased its third-generation system flagship MicroMaxx. This version expands on existing capabilities with two imaging enhancements, new transducers, and wireless connectivity.

The eight-pound, notebook-sized system includes high-performance features such as high-frequency linear and multiplanar transesophageal imaging. The device, which boots up in seconds, delivers image resolution and performance comparable to larger and more expensive cart-based systems, according to the company.

The battery-driven MicroMaxx now has wireless connectivity, allowing a radiologist to realize the benefits and immediacy of a complete ultrasound examination throughout the hospital, wherever needed. Still frames and clips of dynamic images can be immediately transferred from the patient's beside or the imaging lab to the interpreting physician via DICOM networks or SonoSite's PC viewing software, SiteLink.

Other upgrades include two new broadband transducers: the P10/8-4, a high frequency, phased-array probe for pediatric and neonatal radiology; and the SLA/13-6, a high-frequency linear array probe for imaging the vascular system and musculoskeletal and superficial structures.

The system also now includes SonoRES, a smart algorithm that takes advantage of the powerful processing capability of MicroMaxx's Chip Fusion technology. This enables real-time adaptation of speckle reduction in obstetrical, neonatal neurological, and abdominal imaging on the P17, C60e, and P10 transducers. Transcranial Doppler provides imaging at the required power levels for transtemporal, transoccipital, and transorbital windows on the P17 transducer.

A software option called SonoCalc IMT (intima media thickness) aids in the early detection and management of cardiovascular disease.