SONAS® – portable ultrasound device
for stroke detection

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SONAS® Design Concept
Not for sale in the United States. For investigational use only.

The concept of SONAS® describes a portable, battery-powered ultrasound device designed for the non-invasive, transcranial diagnosis of major strokes. SONAS™ utilizes ultrasound microbubbles. Proprietary signal detection algorithms have been developed to assess brain perfusion semi-quantitatively in a comparable fashion (right vs. left hemisphere) and to adapt automatically the acoustic output power to the patient. Signal analysis tools aid in the detection of major ischemic and hemorrhagic events. The SONAS™ Device carries Bluetooth and wireless technology.

Key features
  • portable, battery-powered
  • aids in detection of major strokes (ischemia, hemorrhage)
  • utilizes ultrasound microbubbles
  • use of proprietary signal detection algorithms
  • high signal detection sensitivity
  • favorable safety (low output power)
  • cost effective
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Technical Specifications
SONAS® - Device Description
SONAS is a portable ultrasound device with a quad-core ARM-based application processor running Linux, and a high-resolution four channel A2D converter. A transmit circuit includes high-performance amplifiers and a transformer section to achieve output amplitude. The entire unit is powered by eight standard replaceable “AA” batteries. The SONAS system includes a headset with two ultrasound transducers positioned on each side of the head in the area of the temporal bone window. Each transducer assembly contains two individual transducers in a single mechanical package, including a transmit element and a receive element.
SONAS® - Signal Generation
For improved skull penetration, SONAS transmits ultrasound at a low, sub MegaHertz frequency in an alternating fashion right vs. left. The transmissions on each side also invert the phase angle on an alternating basis, to enable application of pulse inversion in signal processing. Commercially available ultrasound contrast agents (microbubbles) are injected intravenously during the SONAS test procedure. Microbubbles oscillate in the presence of the ultrasound excitation signal, producing harmonic frequencies at multiples of the transmit frequency. Microbubble excitation occurs in the Region of Interest, which is focused over the main supply area of the middle cerebral artery on both sides. When a SONAS test is conducted, the transmit duty cycle is repeated for a total of 40 seconds after injection of the contrast agent.
SONAS® - Data Acquisition
Following microbubble excitation SONAS detects the 4th, 5th, and 6th harmonic frequencies. SONAS conditions the received signals first with filters and amplification in hardware, then applies Pulse Inversion in software to reduce the harmonic interference from the skull boundary. Next, time-boxes are applied to discern signals originating from the two hemispheres independently. Additional time-boxes are applied to ignore parts of the received signals that are not relevant (e.g. close to skull). Ipsilateral Data (transmit/receive on the same side of the head) as well as Contralateral Data (transmit/receive on the opposite side of the head) is acquired and used for further analysis.
SONAS® - Analytic Approach
SONAS measures brain perfusion in both hemispheres using microbubbles as acoustic tracers. The analytic concept is based on Bolus Kinetic Modeling. Similar to MRI- or CT-Perfusion, the contrast agent is administered as a bolus injection. The change in microbubble related acoustic signal strength is monitored over time and displayed as bolus kinetic curves.

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The proprietary analytic algorithm is based on the comparison of the bolus kinetic parameter Time to Signal Peak in a 1:1 comparison right vs. left hemisphere. Other kinetic parameters, such as Time to Arrival, Area Under Curve or Mean Transit Time as well as non-kinetic parameters, such as Acoustic Signal Amplitude, can be compared in the same fashion.
SONAS® - Wireless Capability
Current Wireless Capabilities include secure connection of the SONAS unit to a local WiFi network. Using almost any external computing device (e.g. personal laptop or smartphone), the SONAS unit can be accessed, test data retrieved, and summary reports generated and transmitted to a dedicated via a Web Page Interface.