Ultrasound diagnostic apparatus and ultrasound image producing method

An ultrasound diagnostic apparatus comprising:

• a transducer array;
• a transmission circuit for transmitting an ultrasonic beam from the transducer array toward a subject;
• a reception circuit for processing reception signals outputted from the transducer array having received ultrasonic echoes from the subject to produce reception data;
• an image producer for producing a B mode image based on the reception data obtained by the reception circuit;
• a region-of-interest setting unit for setting a region of interest in the B mode image produced by the image producer;
• an abdominal wall detector for detecting an abdominal wall of the subject in the B mode image produced by the image producer;
• a controller for controlling the transmission circuit and the reception circuit to transmit a ultrasonic beam emitted from the transducer array and so steered as to enter the abdominal wall detected by the abdominal wall detector vertically with forming transmission focuses respectively at a plurality of points set in and near the region of interest to obtain reception data for measuring a sound speed;
• and
• a sound speed calculator for calculating local sound speeds in the region of interest based on the obtained reception data for measuring a sound speed.