1. An apparatus for ultrasonic tissue investigation comprising: ultrasonic transducer means adapted to emit pulsed emissions into tissue; means so to move said transducer means as to scan an area of tissue to be investigated; means to receive pulses reflected from interfaces between tissue components; and means to convert said received pulses into a visual image of the tissue and means to display said visual image, and wherein said ultrasonic transducer means is constructed and arranged so that said emissions of ultrasonic radiation are so pulsed that each pulse has a very rapid fall back period, said fall back period having a fall back rate that is greater than 30 kV/.mu.s.