An apparatus according to an embodiment includes a processing circuit. The processing circuit is configured to obtain first Doppler waveform data related to a left ventricular blood inflow. The processing circuit is configured to detect positions of an E-wave and an A-wave in the first Doppler waveform data, by using the first Doppler waveform data and a trained model trained with training data that includes at least positions of an E-wave and an A-wave in each of a plurality of pieces of second Doppler waveform data related to left ventricular blood inflows and the plurality of pieces of second Doppler waveform data.