Optimization of Common Iliac Artery Sonography Images via an Indigenous Water Phantom and Taguchi’s Analysis: A Feasibility Study

Abstract

Object: Optimization of common iliac artery sonography images using an indigenous water phantom and Taguchi’s analysis was successfully performed to improve the diagnostic accuracy in routine cardiac examination. Methods: A water phantom with two major compartments was developed, which satisfied Taguchi’s unique criterion of optimization analysis. Two or three levels were assigned to five factors, namely, (A) the probe angle, (B) water depth, (C) sonography preset frame rate, (D) amplitude gain, and (E) imaging compression ratio. The resulting Taguchi’s L18 orthogonal array contained 18 combinations of 5 factors, ensuring the same confidence level as a realm of 162 (21 × 34) combinations. The signal-to-noise ratio (S/N) was defined as the minimal difference between the practical survey and predicted areas of 50 mm2 for the sonography imaging scans. The artifact was customized by creating stenosis with a diameter of 8 mm inside a silicon pipe with a diameter of 19 mm. Results: The derived optimal parameters included (A) a zero probe angle, (B) water depth of 6 cm, (C) frame rate of 45 Hz, (D) amplitude gain of 50%, and (E) compress ratio of 50% from 3 independent measurements in each group. Further ANOVA confirmed that the frame rate was a dominant factor, with ss (sum of squared variances) of 56.6%, whereas the error and other terms were suppressed to 20.3% and 11.9%, respectively. The risks of the inappropriate setting of S/N were also discussed to avoid any misinterpretations. Conclusions: The quantified water phantom combined with Taguchi’s approach proved to be instrumental in optimizing the sonography image scan quality in routine cardiac examination.

Keywords

• sonography image quality
• common iliac artery stenosis
• water phantom
• Taguchi’s analysis
• orthogonal array