Quantitative contrast-enhanced ultrasound was performed in 154 thyroid nodules. Papillary thyroid cancer was histologically proven in 64 cases, follicular thyroid cancer - in 9, follicular adenoma - in 56, colloid nodules - in 12, pseudonodules in autoimmune thyroid disease - in 13. Examinations was done using DC-8 scanner (Mindray, China) with a multifrequency linearprobe (7.5-15.0 MHz) in a specialized mode with a low mechanical index (<0.10). SonoVue ultrasound contrast agent (2.4 ml) was used for examinations. The quantitative analysis was performed with built in ContrastQA software in post-processing mode. Quantitative parameters of time-intensity curve (time to peak intensity (TPI) (s), peak intensity (PI) (dB), half of descending time (DT/2) (s), contrast descending velocity for 30 s after peak intensity (DV) (dB/s)) were analyzed. Quantitative parameters were obtained for thyroid nodules and adjacent parenchyma. Corresponding indices and difference were calculated: TPI index (TPI parenchyma/TPI nodule), PI index (PI parenchyma/PI nodule), DT/2 index (DT/2 parenchyma/DT/2 nodule), DV index (DV parenchyma/DV nodule), and DV difference (DV parenchyma - DV nodule). Statistically significant differences were found for the following parameters between groups of benign and malignant nodules (P ≤ 0.05): PI nodule, PI parenchyma, DT/2 nodule, DT/2 index, DV nodule, DV index, and DV difference. The most accurate parameters for thyroid cancer diagnosis were: DT/2 index, DV index, and DV difference. The test “DT/2 index > 1.028 - thyroid cancer” was characterized by sensitivity of 86.1%, specificity of 85.2%, positive predictive value of 87.7%, negative predictive value of 83.4%, and AUC of 0.872. The test “DV index ≤ 0.895 - thyroid cancer” was characterized by sensitivity of 66.7%, specificity of 95.1%, positive predictive value of 94.3%, negative predictive value of 70.0%, and AUC of 0.840. The test “difference DV ≤ -0.020 dB/s - thyroid cancer’’ was characterized by sensitivity of 66.7%, specificity of 95.1%, positive predictive value of 94.3%, negative predictive value of 70.0%, and AUC of 0.842. Diagnostic tests for characterization of different morphological types of thyroid nodules in quantitative contrast-enhanced ultrasound were not found.

Ultrasound examinations data of 118 surgically removed malignant thyroid nodules was retrospectively analyzed. Morphological verification was performed in all cases: papillary thyroid cancer - 89 (75.4%) cases, follicular thyroid cancer - 22 (18.6%), medullary thyroid cancer - 7 (5.9%). The frequency of high suspicious (irregular and ill-defined borders, hypoechogenicity, taller-than-wide shape, microcalcifications) and low suspicious (spherical shape, inhomogeneous hypoechogenicity due to the hypoechoic foci, macrocalcifications, dorsal echo attenuation, pathological vascular pattern) ultrasound signs of thyroid malignancy was evaluated in accordance with nodule size. All nodules were divided into 5 groups according to nodule size: the 1^st group - 32 (27.1%) nodules <1.0 cm, the 2^nd - 37 (31.4%) nodules ≥1.0-<1.5 cm, the 3^rd - 21 (17.8%) nodules ≥1.5-<2.0 cm, the 4^th - 11 (9.3%) nodules ≥2,0-≤2.5 cm, the 5^th - 17 (14.4%) nodules >2.5 cm. Significant correlation between high suspicious sign “hypoechogenicity" and nodule size was found (r_S = -0.205, P = 0.0261). Also low suspicious signs “inhomogeneous hypoechogenicity", “macrocalcifications", and “pathological vascular pattern" significantly correlated with nodule size (r_S = 0.341, P = 0.0002; r_S = 0.328, P = 0.0003; r_S = 0.248, P = 0.0068, respectively). The frequency of inhomogeneous echostructure was increasing with nodule size increase due to appearance of hypoechoic foci of various shape and size (which were forming the picture of inhomogeneous hypoechogenicity). In nodules >1.5 and >1.0 cm frequency of inhomogeneous hypoechogenicity was significantly higher (P = 0.0005 and 0.0009, respectively). Significant difference of the macrocalcification frequency was found between nodules <1.5 and ≥1.5 cm (P = 0.0005) and nodules <1.0 and ≥1.0 cm (P = 0.03). Significant correlation between low suspicious signs number and nodule size was found (r_S = 0.509, P < 0.0001). There was no reason for dividing nodules ≥1.0 cm to the subgroups for biopsy advisability decision.

28 patients with unclear diagnosis (complicated colonic diverticulosis or sigmoid colon cancer) were included in this study. Ultrasound examination was performed in all patients, colonoscopy - in 23 (82.1%), contrast enema - in 10 (35.7%), computed tomography - in 14 (50.0%). 25 (89.3%) patients underwent surgery. The 1^st group included 13 (46.4%) patients with complicated colonic diverticulosis, the 2^nd group - 15 (53.6%) patients with a sigmoid colon cancer (8 of them in combination with diverticular disease). There were no significant differences of clinical findings between groups of patients. The most sensitive ultrasound signs for sigmoid colon cancer diagnosis were: colonic wall structure disorganization, irregular colonic wall thickening, pathological area length <10 cm, and disappearance of haustra. The most sensitive ultrasound signs for inflammatory complications of diverticular disease were: regular colonic wall thickening, wall thickness <15 mm, pathological area length ≥10 cm, pathological area indistinct boundaries, hyperhaustration, and colonic wall normal structure. In order to increase the efficacy of ultrasound in the diagnosis of sigmoid colon cancer, a scoring system has been proposed. In cases, when ultrasound sign for sigmoid colon cancer was obtained, 1 or 2 points were added according to its sensitivity (2 points for signs with sensitivity ≥80%, 1 point for signs with less sensitivity). The diagnostic test “5points or more - sigmoid colon cancer’ had sensitivity of 86.7%, specificity of 100.0%, and area under the curve of 0.959. Ultrasound can be used for differential diagnosis between complicated colonic diverticulosis and sigmoid colon cancer, especially in cases of CT unclear findings or CT contraindications presence.

For assessing the diagnostic value of ultrasound signs of low-lying implantation ectopic pregnancy at early gestational age retrospective study was performed. Retrospective examination of images and medical records of 37 patients with low-lying implantation ectopic pregnancy (main group) was done. The control group was formed from 50 patients with intrauterine pregnancy. We assessed gestational sac location (according to I.E. Timor-Tritsch et al., 2016), cervical length, location of the most distant edge of gestational sac in relation to the internal cervical os, myometrial thickness of anterior uterine wall before 8 gestational week, and number of the previous caesarean deliveries. In the main group gestational sac center in 26 out of 37 cases (70.3%) was located lower than midpoint axis of the uterus while in the control group it was registered in 11 out of 50 cases (22.0%) (P < 0.000). In the main group the most distant edge of gestational sac was located lower than the internal cervical os (category 2) in 9 out of 37 cases (24.3%), at the internal cervical os level (category 1) in 19 (51.4%) cases, and higher than the internal cervical os (category 0) in 9 (24.3%) cases. In the control group category 1 was registered in 4 (8.0%) patients, category 0 - in 46 (92.0%) patients (P < 0.000). Cervical length and myometrial thickness of anterior uterine wall were significantly lower in the main group when compared with the control group (P = 0.022 and 0.035, respectively). Number of the previous caesarean deliveries in the main group was significantly higher when compared with the control group (48.6% (18) versus 16.0% (8)) (P = 0.002). For the diagnostic test «location of the most distant edge of gestational sac is lower than the internal cervical os or at the internal cervical os level (categories 1 and 2) in low-lying implantation ectopic pregnancy diagnosis before 8 weeks of gestation» sensitivity was 75.7%, specificity - 92.2%, AUC - 0.849. For the diagnostic test “location of gestational sac center is lower than midpoint axis of the uterus in low-lying implantation ectopic pregnancy diagnosis before 8 weeks of gestation” sensitivity was 70.3%, specificity - 78.8%, AUC - 0.746.

The peripheral nerves of 200 lower extremities were examined in 100 neurologically healthy children aged 0-17 years. All children were divided into 5 age groups: the 1^st included children aged 0-4 years, the 2^nd - 5-7 years, the 3^rd - 8-10 years, the 4^th - 11-13 years, the 5^th - 14-17 years. Ultrasound signs and quantitative parameters of the sciatic, tibial, and common peroneal nerves were described in accordance with age. The cross-sectional area in transverse scanning and the nerve thickness in longitudinal scanning were measured for all nerve trunks at two segments: proximal and distal. With increase of the children’s age echographic pattern of the examined nerves stayed constant. Intraneural vascularization was not detected. Bilateral differences of cross-sectional area and thickness of the peripheral nerves were not significant at all segments in every age group (P > 0.05). There were no significant differences of the sciatic nerve cross-sectional area values at different segments in every age group (P > 0.05), but for almost all intergroup comparations significant differences were found. The sciatic nerve thickness was significantly increasing in the direction to distal segments in every age group (P < 0.05). Significant differences between older groups (3^rd, 4^th, and 5^th) were not detected. Values of the tibial nerve cross-sectional area and thickness were significantly decreasing in the direction to distal segments in every age group (P < 0.05). Intergroup differences of the tibial nerve cross-sectional area at both segments between older groups (3^rd, 4^th, and 5^th) were insignificant (P > 0.05). Intergroup differences of the tibial nerve thickness between older groups were insignificant only in measuring at distal segment (P > 0.05). Values of cross-sectional area and thickness of the common peroneal nerve were significantly decreasing in the direction to distal segments (P < 0.05). Significant differences of cross-sectional area and thickness of the common peroneal nerve for both segments were found between almost all of adjacent age groups. All the above mentioned can be used for a qualified results interpretation and differential diagnosis of pathological conditions of the lower extremities peripheral nerves in children of different age groups.

Ultrasound examination was performed in 93 patients (15-85 years old) with malignant tumors of the tongue body in order to compare different ultrasound approaches (intraoral, submandibular, and transbuccal) in tumor thickness assessment. Histological investigation with tumor thickness assessment was carried out in all patients. Coincidence of histological and ultrasound measurements was considered as correct if measurement error was ±15%. Percentage error was calculated as % of difference between ultrasound and histological measurements (histological measurements always were taken as 100%; percentage error module was used for analysis). There were no significant differences between results of histological and ultrasound tongue tumor thickness measurements with the use of intraoral, submandibular, and transbuccal approaches. There were no significant differences in tongue tumor thickness value between intraoral, submandibular, and transbuccal ultrasound measurements (with acceptable measurement error ±15%). Significant differences in tongue tumor thickness associated with malignant tumors character (primary or recurrent) were found with the use of intraoral approach (with acceptable measurement error ±15%) (P = 0.01). Ultrasound examination with the use of intraoral, submandibular, and transbuccal approaches can be used for accurate malignant tongue tumors thickness determination, which may affect the treatment.