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

Ultrasound-Guided S1 Transforaminal Epidural Injection Using the In-Plane Approach and Color Doppler Imaging

Recently, several studies have investigated the effectiveness of the ultrasound-guided lumbosacral transforaminal epidural injection. However, the ultrasound-guided S1 transforaminal epidural injection using an out-of-plane approach, which was previously reported, may cause an intestinal injury or intravascular injection because the needle tip tends to be invisible in the out-of-plane approach. In this study, therefore, we report a new method of ultrasound-guided S1 transforaminal epidural injection using the in-plane approach and color Doppler. In addition, we also report the usefulness of color Doppler imaging for finding the S1 foramen and confirming the accuracy of the injection.

An In vitro Study of Guidewire-Related Color Doppler Twinkling Artifacts in Echocardiography

Purpose:

This study sought to determine the association between twinkling artifacts on color Doppler ultrasound and different types of guidewires.

Materials and Methods:

Twenty-two commonly used guidewires were classified into three groups according to decreasing diameter (Group 1, 0.035”; Group 2, 0.018”; and Group 3, 0.014”) and tested in vitro. Severity of twinkling was visually graded into four categories (0–3, from weak to strong).

Results:

The percentages (tips/shafts) of twinkling artifacts were 100%/100% for Group 1; 0%/33.3% for Group 2; and 18.8%/31% for Group 3. The mean scores (tips/shafts) were 2.3/2.7 for Group 1; 0/0.3 for Group 2; and 0.3/0.4 for Group 3. Among them, both two guidewires with strong twinkling artifacts (score = 3) exhibited extensive rough surfaces on microscopic pictures.

Conclusion:

The twinkling artifacts were more likely to present in guidewires with larger diameters (from 0.014” to 0.035”) in our study settings. The surface roughness may be the contribution to the twinkling artifact. Internal heterogeneities, such as types of material, types of coating, tip loading, and spring coil length, do not show influence on the twinkling artifact.

Detection of early DJ-stent encrustation by sonographic twinkling-artifacts - a pilot study

INTRODUCTION

Ureter obstruction caused by a retro-peritoneal tumor is treated by inserting an indwelling ureter splint (DJ-stent). Indwelling duration is limited by cumulative crystalline deposits into the splint, eventually causing the repeated impairment of urine flow. Deciding when a DJ-stent must be replaced is important since belated removal can be accompanied by severe complications. X-ray or conventional sonography do not allow satisfactory evaluation of early incrustation, therefore, the use of sonographic twinkling artifacts (TA) to provide accurate stent surveillance was investigated.

MATERIAL AND METHODS

26 patients with indwelling ureter splints carrying a high risk of developing tumor lysis syndrome (TLS), which is often accompanied by early splint incrustation, were investigated utilizing TA the day after DJ-stent implantation and weekly thereafter. Serum creatinine, uric acid, and urine pH were measured at all TA exams.

RESULTS

Early incrustation of the ureter splint was detected by TA in all patients 1-4 weeks after implantation. Incrustation occurred sooner with increased uric acid levels, and high creatinine or acidic urine accelerated early implant incrustation.

CONCLUSIONS

TA can be used to monitor early crystalline deposits in implanted ureter splints, before they can be detected by conventional sonography or X-ray imaging and before complications occur.

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.