SonoSite and Zonare patents go to heart of hand-carried ultrasound

Like many legal feuds between two major competitors, the one now building between SonoSite and Zonare has broad ramifications that threaten to involve other companies and their products. Whether the case spills into the rest of the ultrasound industry may depend on the specifics of two patents now at issue.

In its pending lawsuit, filed earlier this year against Zonare, SonoSite alleges infringement of its patent number 5,722,412, which addresses portable ultrasound systems weighing less than 10 pounds. In its countersuit, Zonare alleges that SonoSite infringed Zonare's patent number 6,980,419, entitled "Portable Ultrasound Unit and Docking Station."

The SonoSite lawsuit is calculated to gain more than just Zonare's attention, as SonoSite seeks to control territory staked out by its 412 patent (DI SCAN, 3/22/07, SonoSite fires legal shot across bow of ultrasound industry). SonoSite vice president and general counsel Kathy Surace-Smith characterized the patent as both broad and specific, an apparent contradiction of terms borne out, however, by a close look at the patent.

The abstract describes a portable unit that performs both B mode and Doppler imaging using an array transducer, digital beamformer, digital filter, and image processor packaged in one or more enclosures weighing 10 pounds (4.5 kg) or less.

Some 24 specific criteria define these broader elements, adding detail - but in a broad manner. Descriptions of the array transducer cite a linear array and a curved linear array. The device's enclosure is described as "suitable for being held by an operator to ultrasonically scan the body of a patient for reception of echo signals by said array transducer."

The description of the digital beamformer has more specifics, noting its use of analog-to-digital converters, its delay and combining of digital echo signals, and its inclusion of a digital filter coupled to the output, as well as its use of an image processor coupled to the output of the filter.

Exactly how these and other components operate is explained in technical passages accompanied by more than 20 figures, including a block diagram of the system architecture, front and side views of a handheld system and its transducer, a schematic of the transmit/receive application-specific integrated circuit (ASIC), a block diagram of the digital signal processing ASIC, an illustration of how the frame buffer memory is partitioned during 3D imaging, and even waveforms illustrating the operation of the flash suppression processor.

The same dichotomy appears in the abstract for Zonare's patent, which describes how a docking cart provides enhanced features and functionality, such as improved ergonomics, ease of use, a larger display format, external communications connectivity, multiple transducer connections, and increased data processing capabilities.

The patent makes 36 claims, all related to the cart. One describes an internal battery to power the digital communications circuitry and docking cart ultrasound processing circuitry. Another alludes to "a clinician display that displays ultrasound images."

The phrase "at least" appears 11 times in 10 of the claims, describing "at least one":

• set of slider controls for making ultrasound gain-depth-compensation adjustments

• transducer expansion port; a physiological input port that receives physiological data from a physiological sensor

• physiological input port that receives cardiac data from a patient and provides the cardiac data to the docking cart ultrasound processing circuitry

• communications port for supporting communications between the docking cart ultrasound processing circuitry and an external device connected to the communications port

The patent also cited data for a second ultrasound image in the form of "at least two different types of ultrasound image data."

Buried in this legal vernacular may be the future of hand-carried ultrasound. As legal experts unwind the rights tangled within, they may determine how fast - or even whether - the practice of medicine will change.