(Sunday, 7/29/2018) 4:00 PM - 5:00 PM
Room: Exhibit Hall | Forum 1
Purpose: To develop computer-based methods to evaluate image quality in advanced imaging modes of ultrasound: harmonic imaging (HI), spatial compounding (CI), adaptive speckle reduction (SR), and tissue aberration correction (TAC). The parameters used in performance evaluation are image contrast, contrast-to-noise ratio (CNR), and high contrast spatial resolution (HCSR).
Methods: Images of targets in a commercially available general-purpose phantom were acquired in the advanced modes and B-mode using linear probes, keeping the same control settings. Images were analyzed using MATLAB software. For contrast and CNR evaluation, the mean and the standard deviation of the grayscale values of the contrast targets were calculated. Non-linear curve fitting of these data was performed as a function of nominal contrast of each target. This grayscale mapping function (GMF) is affected by the operator control settings and target contrast. Contrast is the gradient of this curve. HCSR was assessed from the full width at half maximum (FWHM) of the filament target along axial and lateral directions. For TAC, an aberration layer was constructed and placed on top of the phantom and HCSR with and without layer was evaluated for this mode.
Results: For all the modes, contrast is highest in the most linear portion of the GMF. In this region, contrast and CNR are highest for CI and smallest for HI. B mode and SR have similar contrast and CNR. Axial spatial resolution is better and more precisely measurable than lateral one, with HI performing better than all the other modes, which have a very similar performance. Spatial resolution is affected by the layer presence both in B mode and in the TAC mode.
Conclusion: For performance evaluation of advanced ultrasound imaging, we demonstrated computer-based methods could be useful in an accurate assessment of the image contrast, CNR, and high contrast spatial resolution.
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