A new imaging method, Bandwidth Imaging, which is related to the bandwidth of the ultrasound Doppler signal is proposed as a classification function for blood and tissue signal in transthoracial echocardiography in the left ventricle. An in vivo experiment is presented, where the apparent error rate of Bandwidth Imaging is compared with the apparent error rate of Second-Harmonic Imaging on 15 healthy men. The apparent error rates are calculated from the 16 myocardial wall segments defined in [M.D., Cerqueira, N.J. Weissman, V. Dilsizian, A.K. Jacobs, S. Kaul, W.K. Laskey, D.J. Pennell, J.A. Rumberger, T. Ryan, M.S. Verani, Standardized myocardial segmentation and nomenclature for tomographic imaging of the heart, Circulation (2002) 539-542]. A hypothesis test of Bandwidth Imaging having lower apparent error rate than Second-Harmonic Imaging is proved for a p-value of 0.94 in three segments in end diastole and in one segment in end systole. When data was averaged by a structural element of five radial, three lateral and four temporal samples the numbers of segments increased to nine in end diastole and to six in end systole. This experiment indicates that Bandwidth Imaging can supply additional information for automatic border detection routines on endocardium.