US detected 33 hyperechoic foci suspected to be stones 26 were confirmed as true positive (i.e. The median overall age of the patients was 4 years (IQR: 3.125, range: 1– 165 months), The median number of days between the US and CT was 13 (IQR: 26, range: 0–81 days). The interval between the US and CT was <3 months for all patients.
Results: Thirty-three abdominal renal US scans of 33 patients (21 males, 12 females) fulfilled the entry criteria. CT examinations done <3 months prior to or after US were retrospectively assessed to confirm the presence of kidney stones as a reference standard. Presence of the twinkle artifact, and stone numbers and sizes were documented. Material and methods: Our retrospective observational study included children who had undergone abdomen/renal ultrasound for kidneys stones in our radiology department between 20. Study results have suggested that the sonographic twinkling artifact may aid in the detection of renal stones with a variety of reference standard imaging modalities, including abdominal radiography, excretory urography, gray-scale sonography, and CT. This is visualized as a random mixture of red and blue pixels in the high-frequency shift spectrum located deep to the interface. The major limitation of our study was that the number of the subjects were small.Background: Twinkle artifact, also known as color Doppler comet-tail artifact, occurs behind very strong, granular, and irregular reflecting interfaces such as crystals, stones, or calcification. Different grades of twinkling artifact on color Doppler ultrasonography were evoked depending on the biochemical composition of renal stones and different central frequencies of transducers. The plastic ball produced grade 1 artifact on L10-5, and grade 0 on other transducers.
Type B stone produced grade 1 artifact on all transducers type C stone produced grade 0 artifact on C4-2, grade 2 on C7-4, and grade 1 on L7-4, and L10-5. Type A stone produced grade 1 artifact on C4-2, grade 2 on C7-4 and grade 3 on L7-4 and L10-5. The size of stones ranged from 6 to 10 mm (mean=8 mm).
Each artifact was graded by two independent observers, and if there was interobserver difference, the consensus was reached. Color Doppler gain was set to the point just below the threshold for color noise. Grading of twinkling artifact was done: 0=absent, 1=present but occupying less than half of a stone, 3=occupying the entire stone and 2=between 1 and 3. All stones were placed in a depth of between 3 and 4 cm in an agar plate. Three types of renal stones (A=90% calcium oxalate +10% calcium hydrogen phosphate, B=50% calcium oxalate +5% calcium hydrogen phosphate +45% ammonium urate, and C=55% urate 35% calcium oxalate +5% ammonium urater +5% calcium hydrogen phosphate) removed from the subjects and one artificially made plastic-ball (D) were examined in vitro with color Doppler ultrasonography. To evaluate the relationship between the degree of twinkling artifact generated on color Doppler sonography and the biochemical composition of renal stones and different central frequencies of transducers.
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