Einar Sagberg

Accurate and reproducible measurement of left ventricular volume and ejection fraction by contrast echocardiography: a comparison with magnetic resonance imaging.

Sigmund Frigstad, T. Skjaerpe, H. Larsson, 2004, Journal of the American College of Cardiology.

Real-time simultaneous triplane contrast echocardiography gives rapid, accurate, and reproducible assessment of left ventricular volumes and ejection fraction: a comparison with magnetic resonance imaging.

Sigmund Frigstad, S. Frigstad, P. A. Steen, 2006, Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography.