Evaluation of in vitro measurement accuracy of a three-dimensional ultrasound scanner.

We have constructed a three-dimensional (3-D) ultrasound scanner to make examinations easier and more accurate. The accuracy of the 3-D scanner has been determined by scanning a three-dimensional model. Lengths, angles, and volume of the model were computed and compared to values determined from physical measurement. Distances between image planes were computed with a mean error of 0.4% of true value. Volume was computed with a mean error of 1.6%, or 0.64 mL +/- 0.72 mL (1 SD). We conclude that the 3-D scanner has a system error of less than 0.4%, that it does not introduce significant new errors, and that the principal source of measurement error is poor lateral resolution due to ultrasound beam width. We believe that the 3-D scanner may be a clinically useful instrument for quantitative echographic measurements.