[Multiple image artifacts with linear sonic transducers].

Abstract

The multielement arrays used nowadays for diagnostic purposes can, by means of digital signal processing, produce exact images with no problem. When physical limits were reached however, geometric image artifacts also became more evident, thereby making diagnosis more difficult or uncertain. Multiple images became especially evident during tests in the early stages of pregnancy, making it harder to differentiate between single and multiple pregnancies , particularly as dynamic processes such as the heart beat can be shown double at a certain phase in the pregnancy. Artifacts were also observed in the form of multiple echos during control checks on the position of intrauterine contraceptive devices and when investigating gynaecological tumors. These artifacts are ascribed to sonic behaviour at interfaces and are representable as a function of the sonic angle of incidence primarily in one plane--the cross section. They appear virtually symmetrical and can be wiped out by moving the sonic transducer. Although there is no problem in recognising the double phenomena as being artifacts in checks on the position of IUD's, all multiple structures should be clarified by suitable examination techniques especially during the early stages of pregnancy and with tumours.