Color Doppler twinkling artifact in intrauterine fetal demise

A novel approach for quantification and analysis of the color Doppler twinkling artifact with application in noninvasive surface roughness characterization: an in vitro phantom study

OBJECTIVES

The twinkling artifact is an undesired phenomenon within color Doppler sonograms that usually appears at the site of internal calcifications. Since the appearance of the twinkling artifact is correlated with the roughness of the calculi, noninvasive roughness estimation of the internal stones may be considered as a potential twinkling artifact application. This article proposes a novel quantitative approach for measurement and analysis of twinkling artifact data for roughness estimation.

METHODS

A phantom was developed with 7 quantified levels of roughness. The Doppler system was initially calibrated by the proposed procedure to facilitate the analysis. A total of 1050 twinkling artifact images were acquired from the phantom, and 32 novel numerical measures were introduced and computed for each image. The measures were then ranked on the basis of roughness quantification ability using different methods. The performance of the proposed twinkling artifact-based surface roughness quantification method was finally investigated for different combinations of features and classifiers.

RESULTS

Eleven features were shown to be the most efficient numerical twinkling artifact measures in roughness characterization. The linear classifier outperformed other methods for twinkling artifact classification. The pixel count measures produced better results among the other categories. The sequential selection method showed higher accuracy than other individual rankings. The best roughness recognition average accuracy of 98.33% was obtained by the first 5 principle components and the linear classifier.

CONCLUSIONS

The proposed twinkling artifact analysis method could recognize the phantom surface roughness with average accuracy of 98.33%. This method may also be applicable for noninvasive calculi characterization in treatment management.

Systematic analysis of factors related to display of the twinkling artifact by a phantom: an optimized investigation

OBJECTIVES

The purpose of this study was to analyze factors related to display of the twinkling artifact by a phantom.

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.

Color Doppler twinkling artifact of calcified cardiac valves in vitro: a not well known phenomenon in echocardiography

The color Doppler twinkling artifact manifests as a rapidly changing mixture of red and blue colors behind strongly reflective structures. The twinkling artifact occurs behind diseased cardiac valves, although the phenomenon is not well described. This study sought to determine the presence of the color Doppler twinkling artifact in calcified cardiac valves in vitro using soft tissue radiography for reference. Seventeen specimens of diseased cardiac valves from patients undergoing valve replacement surgery were studied. The overall sensitivity and specificity for the detection of calcifications using the presence of the twinkling artifact were 66.7% and 81.8%, respectively. If valves with only microcalcifications or smooth calcifications were eliminated from the analysis, all (100%) of the three valves with irregular macrocalcifications exhibited the twinkling artifact. It is important to recognize this artifact because it may lead to misdiagnosis of vascular flow in echocardiography.