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Phase-derivative imaging. II: Effects of beam diffraction and scatterer density
B J Oosterveld1, R L Romijn, J M Thijssen
1Institute of Ophthalmology, Sint Radboudziekenhuis, Nijmegen, The Netherlands.
Ultrasonic Imaging
|July 1, 1989
Summary
This study explored phase derivative (PD) imaging using five algorithms to create ultrasound images. The analytic signal with Wiener kernel (ASW) and analytic signal with squelch (ASS) methods show promise for diagnosing diffuse diseases.
Area of Science:
- Ultrasound imaging
- Medical image analysis
- Signal processing
Background:
- Radio-frequency (RF) echograms are fundamental in ultrasound imaging.
- Phase derivative (PD) analysis offers a novel approach to ultrasound image generation.
- Investigating new algorithms for PD imaging is crucial for advancing diagnostic capabilities.
Purpose of the Study:
- To evaluate the potential of phase derivative (PD) imaging for generating 2D grayscale ultrasound images.
- To compare the performance of five different PD imaging algorithms: ZCS, ASS, ASW, UNP, and SAS.
- To assess the impact of scatterer density and depth on PD image quality and diagnostic utility.
Main Methods:
- Generated PD images using five distinct algorithms (ZCS, ASS, ASW, UNP, SAS) from simulated and experimental RF data.
- Analyzed PD images using grey-level statistics: mean, signal-to-noise ratio (SNR), and full width at half maximum (FWHM) of autocovariance functions (ACVF).
- Systematically investigated image parameters across varying depths and scatterer densities.
Main Results:
- ASW and ASS algorithms produced PD images comparable to conventional amplitude modulation (AM) images for diffuse disease diagnosis.
- ASW and ASS images showed increased mean and SNR with scatterer density, saturating at 5000 cm-3.
- UNP and SAS images were less affected by diffraction but provided limited scatterer density information; ASW/ASS showed reduced speckle size but lower lesion contrast compared to ENV images.
Conclusions:
- The ASW and ASS methods are well-suited for diagnosing diffuse parenchymal diseases using PD grayscale images.
- The reduced speckle in ASW images may benefit focal lesion detection, though contrast is lower than ENV.
- PD imaging, particularly with ASW and ASS algorithms, represents a valuable advancement in ultrasound diagnostic tools.