Twinkling artifact was introduced by Rahmouni et al. in 1996 and defined as a rapidly changing mixture of red and blue behind presumed calcifications in Doppler color flow imaging. There were suggested several plausible causes, such as the phase jitter, the object’s microoscillations, microcavitation, etc.
What are your thoughts on this? What causes the twinkling artifact to appear?
It's seen behind highly reflective objects like calculi and is attributed to the roughness of surface.
Twinkling artifact is caused by highly reflective objects with irregular surfaces. Although it is considered as an artifact, it is a very helpful finding in the detection of nephrolitiasis especially in pediatric cases. Increasing PRF parameter makes it easier to detect the artifact caused by the renal stone.
We frequently see twinkling artifacts under urolithiasis or catheters. Cysts with calcium milk and carotid plaques may also promote these artifacts.
The Doppler Twinkling Artifact; is a form of intrinsic noise generated by a rough and highly reflective object e.g. Lithiasis that, despite being stationary, would generate a rapid alternation between red and blue when interrogated with color Doppler Sonography.
Article Relation of color doppler twinkling artifact and scale or pu...
Article Clinical Significance of Twinkling Artifact in the Diagnosis...
Color Doppler twinkling artifact is a rapid alternation of colors posterior to a stationary echogenic structure, giving the impact of pseudo dynamicity.[1] It appears posterior to bright focus instead of grayscale acoustic shadow that’s why it is also called color comet‑tail. First time it was introduced and described in 1996 by Rahmouni et al., he described twinkling artifact appeared to be generated by a strongly reflecting medium composed of individual reflectors. It was concluded that color Doppler signal close to calcifications should be evaluated carefully to eliminate the twinkling artifact.[2] Twinkling artifact is used since long to identify and confirm renal stones, calcification in the liver, thyroid nodules or fibroid, encrusted indwelling urinary stents, bowel gas, metallic foreign bodies and to some extent gallstones, choledocholithiasis, gallbladder adenomyomatosis, hepatic bile duct hamartoma, and chronic pancreatitis.[3‑6] Nowadays, the twinkling artifact is increasingly used in the identification and differentiation of renal pelvic stones from the adjacent fats in the renal, central echo complex.[7] Color Doppler twinkling artifact is considered useful on the diagnostic point of view, the clinical significance of this artifact is that; it can differentiate among different echogenic structures.[8]As for as the mechanism of this artifact is concerned, and hence the exact mechanism is still unknown, but there are two hypotheses regarding twinkling artifacts. First, which was offered by Rahmouni et al. suggested that when a sound beam is reflected from a rough surface, the acoustic beam split into a complex pattern with phase difference among (PDF) Relation of Color Doppler Twinkling Artifact and Scale or Pulse Repetition Frequency. Available from: https://www.researchgate.net/publication/330852464_Relation_of_Color_Doppler_Twinkling_Artifact_and_Scale_or_Pulse_Repetition_Frequency [accessed May 28 2020]. (PDF) Relation of Color Doppler Twinkling Artifact and Scale or Pulse Repetition Frequency. Available from: https://www.researchgate.net/publication/330852464_Relation_of_Color_Doppler_Twinkling_Artifact_and_Scale_or_Pulse_Repetition_Frequency [accessed May 28 2020]. individual wavelets caused by up and down of the surface, resulting in a long spatial pulse length. Doppler ultrasound machine assumes this complex beam pattern as moment of the reflector.[9‑11] Second – presented by Kamaya et al., it is an intrinsic machine noise probably caused by random time fluctuations in the path lengths of reflected and transmitted sound waves. It was postulated that slight time fluctuations occur due to sound waves strike against a strong reflector with a rough surface. This slight time variation gives rise to aliased Doppler shifts appear as twinkling artifact.[10‑15]Twinkling artifact is very useful in the detection and confirmation of stones, especially in the urinary tract. It has very high specificity and sensitivity as compared to relaying merely on acoustic shadow in grayscale sonography. However, the kidney is very richly supplied with blood flow, and the plexus of vessels in the renal hilum and sinus sometimes superimpose on the twinkling artifact, this changing color appearance in a vessel mimic turbulent blood flow. Intrarenal vascular abnormalities, i.e., arteriovenous fistula and intrarenal artery stenosis cause turbulence and aliasing, but this type of appearance could also be generated by color twinkling artifact caused by a rough surfaced strong reflector such as the kidney stone, foreign‑body, or calcification.[16]A study was published to show the effect of machine settings on the twinkling artifact while using high‑frequency linear array transducer and scanned Struvite stone fragments, wire mesh, and a flat surface placed in a water bath. Variable color‑write priority, gray‑scale gain, pulse repetition frequency (PRF), and spectral Doppler gain were varied. They observed that machine settings effect the appearance of the twinkling artifact. It was also evident that rough surface creates more twinkling artifact (PDF) Relation of Color Doppler Twinkling Artifact and Scale or Pulse Repetition Frequency. Available from: https://www.researchgate.net/publication/330852464_Relation_of_Color_Doppler_Twinkling_Artifact_and_Scale_or_Pulse_Repetition_Frequency [accessed May 28 2020].
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