J Korean Soc Med Ultrasound.  2002 Sep;21(3):207-212.

Effects of Ultrasound Parameters on the Accuracy of Volume Measurement Using Three-Dimensional Ultrasound and Virtual Organ Computer-Aided Analysis (VOCAL)

• Park SH
• Kim SS
• Han H
• Yoon CJ
• Lee JW
• Kim SJ
• Lee KH
• Han JK
• Choi BI

Abstract

PURPOSE: To investigate the effects of various ultrasound parameters on the accuracy of volume measurement using three-dimensional ultrasound (3DUS) and virtual organ computer-aided analysis (VOCALTM).
MATERIALS AND METHODS
Voluson 730 US unit equipped with 4-8 MHz convex volume probe (Medison-Kretztechnik AG, Seoul, Korea) and agar-based US phantom were used. The phantom contained 20 pieces of tumor-mimicking, round-carved hams whose true volume ranged from 8.6 to 10.5 ml. Initially, the center of each ham was placed 5 cm below the surface, and volume data was acquired in various focusing settings (2, 5, 8cm deep), FOVs (8, 10, 12 cm) and sweeping speeds of the probe (low, mid, high as preset on US unit). Change of only one parameter was done while the other parameters remained constant. This process was repeated with placing a ham 8 cm below the surface by adding agar under the same conditions and parameters as with 5 cmdeep phantom to evaluate any effect of object depth on volume measurement. The volume of each piece of ham was measured by using VOCALTM software (Kretztechnik AG, Zipf, Austria) and was converted into % of the true volume. the statistical significance of the difference between volumes measured with different US parameter settings was assessed by Wilcoxon signed-rank test and Friedman test.
RESULTS
Both location of focus and depth of ham significantly affected the measured volume of hams. In 5 cm-deep phantom, the mean volume of 20 pieces of hams with the focus fixated at 2, 5, and 8 cm deep was 132.6+/-3.5%, 127.0+/-1.9%, and 135.3 +/-3.0%, respectively, showing the most accurate result when the depth of ham matched the focusing depth setting. (p<0.01). The mean volume in 5 cm-deep phantom was 127.0+/-1.9% while it was 138.8+/-3.9% with 8 cm-deep phantom (p<0.01). FOVs and sweeping speeds did not affect the accuracy of volume measurement (p=0.22, 0.55).
CONCLUSION
In order to obtain a more reliable assessment and comparison of the volume of lesion with 3D US, it is essential that setting the focus at the same depth as the lesion while maintaining the constant transducer position and acoustic window throughout serial US examinations.

MeSH Terms

Acoustics
Agar
Seoul
Transducers
Ultrasonography*
Agar