Journal of Korean Society of Medical Ultrasound 2002;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).
Seong Ho Park, Sam Soo Kim, Heon Han, Chang Jin Yoon, Joon Woo Lee, Seog Joon Kim, Kyoung Ho Lee, Joon Koo Han, Byung Ihn Choi
1Department of Radiology, Kangwon National University College of Medicine, Korea. sskim@kangwon.ac.kr
2Department of Radiology, Seoul National University College of Medicine, Korea.
  Published online: September 1, 2002.
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.
Keywords: Ultrasound)US), experimental; Ultrasound)US), three-dimensional
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