A comparison of sector and linear array scanners for the measurement of the fetal femur.
This study was designed to determine whether differences between sector and linear array scanners introduce variability in fetal femur length measurements, used to determine gestational age. Twenty transducers from 15 machines were tested with the manufacturers' approval. Machines were coded to maintain anonymity. Three different sized sections of plastic straws were scanned in a water bath. All measurements were made by the same investigator. Measurements were adjusted to compensate for the difference in sound velocity in water, which introduced a 3.36 per cent error in apparent depth of the image for linear array scanners, and a 3.36 per cent error in apparent depth and length for sector scanners. A large variation in measurements was obtained, although the differences were usually within acceptable limits (approximately 4 per cent). Linear array scanners were found to give similar readings as sector scanners.
D005314:Embryonic and Fetal Development; D005260:Female; D005269:Femur / Q000254:growth & development*; D005865:Gestational Age; D006801:Humans; D011247:Pregnancy; D014465:Ultrasonics; D014463:Ultrasonography