Accuracy of in-vitro volume estimation of small structures using three-dimensional ultrasound.
We describe an ultrasound probe for three-dimensional transvaginal imaging. The transducer was an annular array with a center frequency of 7.5 MHz which was rotated with an internal stepper motor. The probe had no external moving parts, and the total volume covered by a full rotation defined a half sphere. The raw digital data from the scanner were transferred to an external PC for three-dimensional reconstruction. We evaluated the three-dimensional imaging system by measuring the volumes of phantoms (range 24.8-3362.5 mm(3)) in a water tank, and found good correlation with true volumes (two observers' measurements gave a linear regression with a slope of 1. 010 and R(2) = 0.993, and a slope of 0.956 and R(2) = 0.993, respectively). The size of the point-spread function was used in the calculations to eliminate the effect of under- or overestimation due to the limited ultrasound beam resolution. An example of data acquisition, volume estimation and imaging of an embryo less than 8 weeks old in vivo with the brain cavities and body is given. We conclude that the three-dimensional reconstruction and volume estimation were accurate and repeatable.
Berg
S
S
Department of Physiology and Biomedical Engineering, Norwegian University of Science and Technology, Trondheim, Norway. sevald.berg@med.ge.com
Torp
H
H
Blaas
H G
HG
D004622:Embryo, Mammalian / Q000000981:diagnostic imaging; D005260:Female; D005333:Fetus / Q000033:anatomy & histology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D066298:In Vitro Techniques; D019047:Phantoms, Imaging; D011247:Pregnancy; D016216:Ultrasonography, Prenatal / Q000295:instrumentation / Q000379:methods*