Image from Touch Prime Ultrasound system

Hemodynamic Evaluation and Measurement: Overcoming Limitations for Flow

Study: University Clinic in Regensburg evaluates Carestream Touch Prime Ultrasound System for hemodynamic evaluation and measurement.

For hemodynamic evaluation and measurement, conventional Doppler ultrasound can only provide a partial picture. A persistent limitation has been the angle of insonation for Doppler examinations.

Calculating the velocity of a flow relies on knowing the precise angle of the ultrasound beam relative to the direction of flow. In conventional ultrasound systems, the practical insonation angle is limited to around 60°. For greater angles, even small errors in the angle can cause unacceptably large distortions in the results.Image from Touch Prime Ultrasound system

Overcoming this restriction for evaluating flow in vessels requires repositioning the transducer which can be uncomfortable for the sonographer. Additionally, the limitation is not as easy to work around when assessing regions of turbulent blood flow. An example is trying to understand the effects of stenoses in vessels or valves, or when evaluating fistulae.

Overcoming angular restrictions

Smart Flow imaging technology in the CARESTREAM Touch Prime Ultrasound Systems overcomes the angular restrictions. It generates a part of the ultrasound vibration that is effectively at a right angle to the beam. The system then interprets the resulting 2D interference patterns in the received ultrasound signal to present a more complete picture of the flow, representing it with shaded color-coding and arrows.

For turbulent regions, the Smart Flow technology provides insight into even complex flows. And even for less complicated imaging – when the flow in a vessel can be measured independently of the angle to the transducer – it makes the examination easier for the sonographer and the patient.

Testing Smart Flow technology for hemodynamic evaluation and measurement

While the concept sound sounds attractive, as with any innovative technology, the real test is how well it can be applied in day-to-day work. Our ultrasound center in the University Clinic in Regensburg explored the practicality and applicability of Smart Flow technology for hemodynamic evaluation and measurement.

During the evaluation, different sonographers tested the CARESTREAM Touch Prime Ultrasound System for various clinical questions in over 200 patient examinations.


We concluded that Smart Flow enables an intuitive visual representation of the blood flow in all directions. We found it beneficial when there is difficulty in obtaining a reliable angle of insonation. It is also beneficial for visualizing complex blood flow patterns – including turbulent regions – to evaluate clinical anatomies like internal carotid artery stenoses in the vicinity of a bifurcation, arteriovenous fistulae, thromboses, and aneurysms. It can also be used to make measurements that are independent of the angle of the transmission beam.

Additionally, Smart Flow allows for a faster workflow because the overall hemodynamic situation can be evaluated without further transducer manipulation. We also noticed more consistent results, including when compared for different examining sonographers.

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