A New Criterion for Shear Wave Elastometric Assessment Using Modulus of Stiffness Difference between Object and Environment.

Ultrasound shear wave elastography is a modern method that is based on measuring the shear wave velocity making it possible to determine stiffness of soft biological tissues at an arbitrary point (point elastography) or to construct a two-dimensional color image with a subsequent point measurement of stiffness (two-dimensional elastography) and therefore to compare the stiffness of an object with a medium or objects with each other. The aim of the study is to develop a new criterion for the comparative assessment of objects with different stiffness during shear wave elastometry: modulus of stiffness difference between object and environment. Materials and Methods: Using the original technology of building two-dimensional color elastogram, point and two-dimensional shear wave elastography were performed using linear sensors on commercial ultrasound scanners: Aixplorer (SuperSonic Imagine, France), Acuson S2000 (Siemens, Germany), and Verasonics acoustic system (Verasonics Inc., USA) with an open architecture to determine the stiffness values of focal inclusions and compare them with each other with the help of a new comparative elastomeric assessment criterion: modulus of stiffness difference between object and environment. First, the accuracy of the scanners under test was compared on a calibrated Elasticity QA Phantom, model 049 (Computerized Imaging Reference Systems Company, USA) with a known stiffness of various inclusions and thereafter on an uncalibrated BP1901 phantom (Blue Phantom, USA) with unknown stiffness of inclusions. The obtained values were compared to determine the influence of subjective factors on the measurement results. Results: To assess the stiffness of the foci and compare the values with each other taking into account the rigidity of the environment, it is proposed to use a new criterion for the comparative assessment - the modulus of stiffness difference between focus and environment, which quantitatively characterizes the difference between these values. According to this criterion, all three ultrasound scanners have been established to show high and comparable accuracy in determining the stiffness of inclusions within the homogeneous medium in the experiments on phantoms. Two-dimensional shear wave elastography has revealed the effect of the control volume size and the correctness of the color scale setting, especially in the heterogeneous objects, on the results of elastometry. Methodological techniques to reduce the influence of subjective factors have also been proposed. Conclusion: The study has showed the possibility of using the modulus of stiffness difference between object and environment as a new criterion for comparative assessment of objects in shear wave elastometry taking into account stiffness of the environment. To reduce operator-dependence, it is necessary to take into consideration both the way of realizing elastometry (point or two-dimensional color elastography) and a number of other methodological factors.

[Immediate and long-term results of nephrectomy with inferior vena cava thrombectomy in renal cell carcinoma].

Results of treatment of 32 patients after nephrectomy with thrombectomy for renal cell carci-noma complicated by tumor thrombosis of the inferior vena cava were analyzed. The study in-cluded patients only with II - IV clot levels: 26 patients with T3b - the length of the thrombus 5.1 +/- 1.75 cm, 6 patients with T3c - the length of a thrombus - 14.8 +/- 0.98 cm. One patient (3.1%) died due to pulmonary artery thromboembolia in immediate postoperative period. 1-2 degrees Clavier Complications were observed in 11 patients, 3-4 degree - in two (6.2%) patients. 90.4% of patients had metastases in distant organs and (or) in the regional lymph nodes, which nega-tively affected the survival rates of patients - 5-year survival rate was 36%. The presence of lymphogenous metastases, MSKCC criteria were factors affecting survival rate. Survival rates of patients with T3b and T3C levels were not statistically different. The results of postoperative systemic targeted therapy were significantly statistically better than the results of immunotherapy.

[Ultrasound study of the liver and kidneys after different types of resection].

The ultrasound pattern of hepatic and renal changes after different types of resection is depicted. Ultrasound studies were performed in 335 patients operated on for focal hepatic masses and in 72 patients operated on for focal renal masses. The authors identified 3 patient groups after hepatic resection (segment-oriented liver resection (99 patients), portal hemihepatectomy (n=163), and extended hemihepatectomy (n=73)) and 3 patient groups after renal resection (planar (n = 83), wedge (n = 104), and frontal (n = 66)). It has been established that the number and location of hepatic veins in the liver stump, which the authors have designated as a hepatic vein rule, are of basic value in defining the type of hepatic resection. To determine the type of renal resection, it is essential to assess the shape of the organ and the area of its resection. The found echosemiotic patterns allow the type of performed resection of parenchymatous organs to be correctly determined in the majority of cases.

[Surgical treatment of colorectal cancer liver metastases with microwave thermoablation].

Domestic device for destruction of tumors by microwave power was designed. Initial series of laboratory experiments were performed with microwave liver ablation. Primary series of patients with colorectal cancer metastases to the liver demonstrate positive results. Short-term exposure, programmable shapes and sizes of ablative zones are the distinctive advantages of microwave thermoablation (MTA). 329 patients underwent liver resections during 2005-2010 years.108 patients had colorectal cancer metastases to the liver. 52 (48,14%) patients had bilobar liver lesions. Among them 11 patients underwent liver resection combined with MTA of contralateral liver lesions. Reliable differences in survival rates among patients with monolobar and bilobar metastatic lesions were not observed. Median of survival rate amounted 22.8 months in patients operated for metastatic colorectal cancer. Variants of surgical treatment are proposed.