Image quality influences the assessment of left ventricular function: an intraoperative comparison of five 2-dimensional echocardiographic methods with real-time 3-dimensional echocardiography as a reference - Großgasteiger, Manuel; Hien, Maximilian; Graser, Bastian; Rauch, Helmut; Motsch, Johann; Gondan, Matthias (Journal of ultrasound in medicine, 2014)