Informative and diagnostic value of ultrasound twinkle artifact in verification of urinary stones

In cases of small urinary calculi (less than 5 mm) in the seroscale ultrasound examination mode, differential diagnosis between the suspected renal calculus and hyperechoic foci caused by other factors (vascular or parenchymal) is difficult. On the back of this, it is important to find an additional diagnostic ultrasound criterion for reliable visualization of calculi in the urinary tract. The purpose of the study was to evaluate the informative value and diagnostic significance of the ultrasound twinkle artifact in verifying small urinary calculi. Material and methods. The study included 100 patients with urolithiasis and 25 healthy adults. Patients with urolithiasis were divided into two groups (N 1 and N 2 with an equal number of patients in them), healthy individuals made up group N 3. All persons included in the study underwent ultrasound examination in B-mode and color Doppler mapping of the urinary system organs, multispiral computed tomography without contrast enhancement of the abdominal cavity and the retroperitoneal space. Equipment used: ultrasonic scanners with a convex sensor (2.5–5.0 MHz, Mindray MX7, China; Philips, Holland; Toshiba, Japan) and a Siemens SOMATOM Drive 2´128 computed tomograph (Siemens Healthineers, Germany). The ultrasound twinkle artifact was analyzed as a diagnostic criterion in verifying urinary tract calculi with a size of less than 5 mm. Results. Patients in group 1 first underwent native multispiral computed tomography, then ultrasound kidneys examination was performed for those of them who had stones in the urinary tract to identify the twinkle artifact. Multispiral computed tomography made it possible to identify 108 urinary stones in patients of this group. With the help of ultrasound examination in B-mode, conducted in patients selected according to the results of multispiral computed tomography, 71 concretions were recorded, in color Doppler mapping mode – the flicker artifact was present in 142 cases. Patients in group 2 first underwent ultrasound examination of the kidneys and the urinary tract with special settings to detect the flicker artifact, followed by multispiral computed tomography of the abdominal cavity and the retroperitoneal space without contrast enhancement. With the help of ultrasound examination conducted in B-mode, 35 urinary stones were found in patients of this group. When using the color Doppler mapping mode with additional settings and registration of the flicker artifact, 68 more calculi were found in the urinary tract. Purposefully performed multispiral computed tomography of the kidneys confirmed calculi in all 68 cases in different parts of the urinary tract recorded during ultrasound examination. At this, 4 patients were diagnosed to have multiple (up to 7) urinary calculi. The analysis of using the flicker artifact as an ultrasound criterion in detecting urinary calculi showed a high informative value of ultrasound examination with additional settings (sensitivity and specificity – 94.4% and 100%, respectively). According to the results of the study, it can be assumed that the flicker artifact during ultrasound examination in the color Doppler mapping mode is a diagnostic feature (criterion), and not an "artifact". Conclusion. The use of the flicker artifact as an additional criterion to the standard ultrasound examination of the kidneys and the urinary tract gave the opportunity to improve the diagnosis of small urinary stones. At this, the informative value of ultrasound examination with additional settings for the flicker artifact reached 94.4% in sensitivity, and the specificity reached 100%.