Journal of Ultrasound in Medicine, Vol 4, Issue 10 525-530, Copyright © 1985 by American Institute of Ultrasound in Medicine
A comparison of sector and linear array scanners for the measurement of the fetal femur
P. Jeanty, G. J. Beck, F. A. Chervenak, F. W. Kremkau and J. C. Hobbins
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.
