White Paper | Results of an evaluation of Smart Flow technology and the touch screen user interface at the University Clinic, Regensburg

Dr. Isabel Wiesinger, Prof. Dr. Ernst-Michael Jung, Head of the Ultrasound Center, and Prof. Dr. Christian Stroszczynski, Chair of the Radiology Institute

University Clinic, Regensburg

The possibilities for real-time imaging in today’s high end ultrasound diagnostics open various important alternatives at the patient’s side. Apart from excellent image quality – resulting from both high-resolution transducer technology and advanced digital data processing – it needs to be easy for users to access the functionality the system offers. That is, the system needs to be both technically good and practical.

When it comes to hemodynamic evaluation, one limit of traditional ultrasound has been the angle of insonation for Doppler examinations. The rate of flow in the vessel uses the angle of ow relative to the ultrasound beam for the calculation. The calculation stops working if the ultrasound beam is perpendicular to the vessel (90°), since then there isn’t any component owing in the direction of the beam. In practice, the hemodynamic measurement is significantly compromised for angles of insonation greater than 60°, because small errors in assessing the direction can cause large discrepancies in the results.

 
67-year-old patient with Osler’s disease.
The vessels are ectatic, as shown in the B image (left). The multiple fistulae lead to a turbulent shunt flow. The turbulences can be recognized in the Smart Flow both by the different hues, and by the arrows representing the flow direction (middle). The flow speed is represented by the length of the respective arrows (right).
 
An angular-independent representation of blood flow

Smart Flow 1) is an imaging technology, available on CARESTREAM Touch Prime Ultrasound Systems, that presents the blood flow in all directions independently of the angle of insonation.

To overcome the angular limitations of conventional ultrasound, the proprietary Smart Flow generates a component of the ultrasound vibration that is effectively perpendicular to the transmitted beam, using a technique called transverse oscillation 2), 3). This creates 2D interference patterns in the received ultrasound signal, which can be interpreted to calculate both the traditional axial component and the transverse component. The system can then display the Smart Flow information with color-coding and arrows. The strength of the flow is represented both by the color and the length of the arrow; additionally the orientation of the arrow shows the direction of the flow. That is, Smart Flow not only eliminates the angular dependence, it also enables the representation of complex ows.

At the University Clinic in Regensburg, different sonographers tested the CARESTREAM Touch Prime Ultrasound System for various clinical questions, in over 200 patient examinations. They evaluated haptics and appearance, B-image, color representation, spectrum analysis, resolution and contrast, as well as the clinical applicability. This included an evaluation of Smart Flow, both whether it was useful for evaluating hemodynamics, and also to judge its usability. By adjusting the gain and pulse repetition frequency, we could get a convincing ow representation in both venous low-flow regions, and in the high- ow regions of extreme arterial stenoses and stulae.

We concluded that Smart Flow enables an intuitive visual representation of the blood flow in all directions. This means it is suitable when there is difficulty in obtaining a reliable angle of insonation, or for visualizing complex blood ow patterns - including turbulent regions - to evaluate clinical anatomies like internal carotid artery stenoses in the vicinity of a bifurcation, arteriovenous stulae, thromboses, and aneurysms. It can also be used to make measurements that are independent of the angle of the transmission beam. Smart Flow allows for a faster work flow, because the overall hemodynamic situation can be evaluated without further transducer manipulation. We also notice more consistent results, including when compared for different examining sonographers.

 

Touch screen usability

A further decisive criterion is how quickly and effectively the technologies offered by the CARESTREAM Touch Prime Ultrasound System can be both used and adapted to the needs of individual sonographers.

The ease of access to the possibilities the system offers is through the exclusive operation using a touch screen. Each user can customize this according to their preferences, with the support of optimization functions. This allows each user to arrange quick access to the parameters that are important to them. The lack of knobs and a keyboard also makes disinfecting easier, which simplifies the process for examining infected patients, and using the system peri-interventionally.

Each user can organize their most frequently used controls in groups around the trackball, which is fully integrated in the touch screen. The smooth user interface also simplifies disinfection.

Each user can organize their most frequently used controls in groups around the trackball, which is fully integrated in the touch screen.
The smooth user interface also simplifies disinfection.

 

Dr. Isabel Wiesinger, University Clinic, Regensburg
Dr. Wiesinger was responsible for the evaluation of the CARESTREAM Touch Prime Ultrasound System. She has been a resident physician in the Radiology Institute, University Clinic, Regensburg, since 2013, with a research focus in ultrasound.

Prof. Dr. Ernst-Michael Jung, Head of the Ultrasound Center, University Clinic, Regensburg
Prof. Jung has been Head of the Ultrasound Center at the University Clinic Regensburg since 2010. He is a member of numerous professional organisations, has worked in organizing various congresses, and reviews for a number of German and international medical journals.

Prof. Dr. Christian Stroszczynski, Chair of the Radiology Institute, University Clinic, Regensburg
Prof. Stroszczynski has been Chair of the Institute of Diagnostic Radiology at the University Clinic Regensburg since 2010. He is a member of various professional organisations, and reviews for numerous German and international medical journals as a specialist in diagnostic and interventional radiology of the abdomen, vascular medicine, and interventional oncology and oncoimaging.

1) A.Anand, Carestream Touch Prime Ultrasound System: Technology White Paper, CARESTREAM, July 2015

2) J.A. Jensen, A new estimator for vector velocity estimation [medical ultrasonics], IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control ( Volume: 48, Issue: 4, July 2001 )

3) J.A. Jensen ; P. Munk, A new method for estimation of velocity vectors, IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control ( Volume: 45, Issue: 3, May 1998 )