Systematic Analysis of Factors Related to Display of the Twinkling Artifact by a Phantom

Abstract

he twinkling artifact was first described by Rahmouni et al 1 as a rapidly changing mixture of red and blue behind a strongly reflective structure. It has been extensively studied, and its methodological aspects and concrete applications continue to be investigated. Acoustic shadowing as the main principle for diagnosing renal stones has been well known for many years; however, some recent studies reported sensitivity for stone detection as low as 24%. 2 Since the twinkling artifact has been adopted as an additional sonographic feature of urinary stones, the sensitivity of sonography has improved substantially, and use of the twinkling artifact in the diagnosis of renal and ureter stones has been proven in many studies. [3][4][5][6] Lee et al 7 suggested that more than 80% of urinary stones had the twinkling artifact, and no false-positive findings were observed during the scanning of 36 stones in their study. An Optimized InvestigationMeng Wang, MD, Jie Li, MD, Jing Xiao, MD, Dandan Shi, MD, Kaining Zhang, MD Received March 28, 2011, from Methods-An in vitro phantom made of sandpaper was designed to mimic rough physiologic surfaces prone to generating the twinkling artifact. Sandpaper strips embedded in a plastic box were scanned through a water path under different machine settings with only 1 parameter varied each time. After choosing the best settings for displaying the twinkling artifact, 4 types of sandpaper with different roughness were scanned. The resulting images were recorded at random, and the number of color pixels in the color box of each image was calculated by a custom-designed program developed using commercially available software. All data were then evaluated by regression analysis, a paired 2-tailed Student t test, and single-factor analysis of variance.Results-The highest color write priority and color gain, which were just below the threshold for color noise, a focus depth setting below the sandpaper, a maximum wall filter under a higher pulse repetition frequency, and a color box adjusted properly in the fundamental imaging mode (P < .001) were found to most readily improve the twinkling artifact intensity. The roughness of the sandpaper was shown to be highly correlated with the twinkling artifact intensity (R 2 = 0.832; P < .001).Conclusions-The twinkling artifact was influenced by some machine parameters and the roughness of the sandpaper. By adjusting some ultrasound machine parameters, a better image reflecting the twinkling artifact can be shown in clinical practice and research.

Quantitative Evaluation of the Effects of Urinary Stone Composition and Size on Color Doppler Twinkling Artifact: A Phantom Study

“…The sampling box was adjusted to 1.5 × 1.0 cm in the fundamental imaging mode. All of these parameters were set to optimize the display of twinkling artifact . When twinkling artifact was continuously showed, the color Doppler pictures were recorded for each stone phantom.…”

Noninvasive Prediction of Renal Stone Surface Irregularities by Numerical Analysis of the Color Doppler Twinkling Artifact: An Ex Vivo Study

“…According to the high sensitivity of the twinkling intensity to the imaging system settings, the US system should be calibrated before data acquisition. Furthermore, these settings should be kept unchanged during the imaging of all renal stones to eliminate bias in the final data.…”

Combining ultrasonography and noncontrast helical computerized tomography to evaluate Holmium laser lithotripsy

“…There are no uniform or strict criteria to evaluate the intensity of twinkling artifacts, which makes the evaluation subjective and operator-dependent. Referring to Gao et al [10] and Wang et al, [11] we quantified the twinkling artifact intensity (TAI) by calculating the number of color pixels in each artifact. In Adobe Photoshop CS5, the background gray pixels were deleted, the background was masked in black, and the images containing only color pixels from twinkling were saved.…”