A Preliminary Study on the Adaptive SNR Threshold Method for Depth of Penetration Measurements in Diagnostic Ultrasounds

Abstract

Maximum depth of penetration (DOP) is among the most relevant parameters in quality assurance programs for Ultrasound (US) scanners. Nowadays, a generally-accepted protocol for DOP estimation is still awaited and, in common practice, DOP is visually assessed despite the low accuracy. To overcome the eye-based assessment subjectivity, automatic image analysis methods have been proposed in literature. The present work focuses on a novel automatic method, namely the adaptive Signal to Noise Ratio (SNR) threshold method (AdSTM), developed in the MATLAB environment, by comparing it with an existing automatic approach, namely the tangent threshold method (TTM), and the mean judgment of eight observers (naked eye method). The three investigated methods were applied on data acquired from four US scanners for general purpose imaging, equipped with linear, convex, and vector array probes. Tests were carried out in two different configuration settings (raw scanner and default preset working conditions). AdSTM outcomes were tested by means of Monte Carlo Simulations. Most of measurement results were compatible despite the fact that the AdSTM seemed to be more sensitive and faster than the TTM. The results analysis confirms the higher dispersion of the naked eye method in DOP assessment with respect to the proposed automatic methods.

A Comparative Study on Depth of Penetration Measurements in Diagnostic Ultrasounds Through the Adaptive SNR Threshold Method

“…As described in [19], [21], the AdSTM image analysis SNRbased method for DOP assessment (Fig. 1) was developed by 2 > REPLACE THIS LINE WITH YOUR MANUSCRIPT ID NUMBER (DOUBLE-CLICK HERE TO EDIT) < processing phantom and in-air clips (the latter obtained by decoupling the probe from the phantom surface).…”

“…The method, implemented through a custom-written MATLAB function, post-processes video clips taken from phantom and air observations by averaging N consecutive frames to produce two average images (Iph and Iair). Then, a rectangular Region Of Interest (ROI) of fixed width is automatically drawn from Iph and Iair to compute the signal and the noise contributions, respectively [19]. The SNR curve is then estimated as a function of depth z, and the threshold thSNR is computed as follows:…”

“…The Adaptive SNR Threshold Method (AdSTM), a novel image analysis SNRbased method for DOP assessment, was recently introduced to address these limitations. It is based on automatic threshold determination, thus improving the method in [14], and as shown in the previous preliminary studies [19], [20], it has the advantage of increasing the reliability and reproducibility of the results. The goal of the current study is thus to test the AdSTM across a variety of US diagnostic systems and configurations available on the market, including different probe models, and to analyze the DOP variation in response to different probe operating frequencies at distinct levels of medium attenuation.…”

Comparative evaluation of three image analysis methods for angular displacement measurement in a MEMS microgripper prototype: a preliminary study

“…It is important to underline that the experimental setup is the same, except for the three different methods. Following the procedure adopted in [7], Type A and Type B uncertainties will be combined [27], as follows (1): where Type A uncertainty, A, has been calculated directly from the standard deviation of the experimental data, while Type B uncertainty, B, has been obtained considering the uncertainties due to the power supply (evaluated from the datasheet), the optical system [7]- [9], the angle measurement, which uncertainty contribution has been assessed by means of a Monte Carlo simulation [28]- [29] in order to estimate the uncertainty related to the three implemented method.…”

Doppler flow phantom failure detection by combining empirical mode decomposition and independent component analysis with short time Fourier transform

“…They can simulate the main acoustic characteristics of biological tissues and reproduce repeatable flows whose regimes are similar to those in blood vessels [4]- [7]. To date, the lack of a generally accepted standard for B-mode and Doppler [8]- [12], has led to a limitation on US phantoms use. It should be noticed that, even though such devices are widespread on the market, they are still not included in a shared standard that focuses in detail on periodic and objective checks of their metrological and functional characteristics.…”