Experimental and Numerical Investigation of Acoustic Emission Source Localization Using an Enhanced Guided Wave Phased Array Method.

To detect damage in mechanical structures, acoustic emission (AE) inspection is considered as a powerful tool. Generally, the classical acoustic emission detection method uses a sparse sensor array to identify damage and its location. It often depends on a pre-defined wave velocity and it is difficult to yield a high localization accuracy for complicated structures using this method. In this paper, the passive guided wave phased array method, a dense sensor array method, is studied, aiming to obtain better AE localization accuracy in aluminum thin plates. Specifically, the proposed method uses a cross-shaped phased array enhanced with four additional far-end sensors for AE source localization. The proposed two-step method first calculates the real-time velocity and the polar angle of the AE source using the phased array algorithm, and then solves the location of the AE source with the additional far-end sensor. Both numerical and physical experiments on an aluminum flat panel are carried out to validate the proposed method. It is found that using the cross-shaped guided wave phased array method with enhanced far-end sensors can localize the coordinates of the AE source accurately without knowing the wave velocity in advance. The proposed method is also extended to a stiffened thin-walled structure with high localization accuracy, which validates its AE source localization ability for complicated structures. Finally, the influences of cross-shaped phased array element number and the time window length on the proposed method are discussed in detail.

Pathological Intraplaque Hemorrhage as the Gold Standard to Assess the Efficacy of Ultrasound in Predicting Vulnerable Carotid Plaque Rupture.

OBJECTIVE: To assess the clinical utility of ultrasound in predicting the risk of carotid vulnerable plaque rupture using pathological intraplaque hemorrhage as the gold standard. METHODS: A total of 118 patients who underwent endarterectomy due to symptomatic carotid artery stenosis were enrolled. Conventional ultrasound assessed the plaque thickness, area stenosis rate, echo, and surface morphology. Neovascularization were assessed by contrast-enhanced ultrasound (CEUS) and tracing intraplaque nonenhanced areas. According to neovascularization grade (0-4), plaques were classified as low-, intermediate-, and high risk. Fresh intraplaque hemorrhage within the pathology was adopted as the gold standard for diagnosing plaque rupture risk. Thus, we divided patients into ruptured risk and nonruptured risk groups to assess the value of crucial factors for plaque rupture risk using ultrasound. RESULTS: Of the 118 patients, hypertension accounted for 71.2%, hyperlipidemia 68.6%, diabetes 52.5%, and statin history 64.4%. In the rupture risk group, diabetes, smoking, and stenosis rate were significantly higher than the nonrupture risk group (P < .001); plaque thickness ≥4 mm (P > .05); and mainly hypoechoic with irregular surface morphology (P < .001), nonenhanced areas in the plaques (P < .001), and neovascularization >grade 2 (P < .001). Compared with the low-risk group, plaque rupture risk was 7.219 times higher in the medium-risk group and 18.333 times higher in the high-risk group. The kappa value of the interobserver consistency of crucial ultrasound parameters was >0.75, and the intraclass correlation coefficient was 0.919 (P < .01). CONCLUSIONS: Both conventional ultrasound and CEUS have significant clinical importance in the prediction of rupture risk in vulnerable carotid plaques, thereby enabling stroke risk stratification and the assessment of plaque rupture risk.

Application of laparoscopic ultrasound in retroperitoneal radical nephrectomy for renal cell carcinoma with Type II inferior vena cava tumor thrombectomy.

Background: The aim of this study was to investigate the application value of laparoscopic ultrasound (LU) in retroperitoneal radical nephrectomy for renal cell carcinoma with Type II inferior vena cava tumor thrombectomy (RRN-RCC-TII-IVCTT). Methods: The clinical data (operative time, length of tumor thrombus, tumor length, intraoperative bleeding, clinical stage, histological type, residual tumor tissue, and postoperative follow-up) of 6 patients who underwent LU-guided RRN-RCC-TII-IVCTT were retrospectively analyzed, and the intraoperative experience of LU was also summarized. Results: All 6 patients recovered well with liver and kidney functions returning to normal, and no tumor recurrence, metastasis, or vena cava tumor thrombus. Conclusions: LU-guided RRN-RCC-TII-IVCTT is a feasible treatment option, which locates the tumor accurately by retroperitoneal approach and provides the additional benefit of reduced intraoperative bleeding and shortened operative time, also achieving the much sought-after goal of precision.

Clinical application of ultrasound-guided mediastinal lymph node biopsy through cervical mediastinoscopy.

BACKGROUND: Cervical mediastinoscopy is useful for diagnosing lung and mediastinal disease. Ultrasound is a safe real-time diagnostic tool widely employed in many surgical fields. Ultrasound was used in cervical mediastinoscopy in our cohort with satisfactory results. This study investigated the safety, feasibility, and availability of video-assisted mediastinoscopy (VAM) combined with ultrasound for mediastinal lymph node biopsy. METHODS: A total of 87 cases involving cervical mediastinal lymph node biopsy performed from November 2015 to May 2020, with complete clinical and pathological information, were retrospectively analyzed in the Department of Thoracic Surgery at Beijing Chaoyang Hospital. The cohort was divided into two groups: ultrasound-guided biopsy under video-assisted mediastinoscopy (UVAM) (44 cases) and routine VAM (43 cases). Operation time, biopsy number and nodal stations, postoperative complications, pathological conditions, and surgical difficulty were compared between the two nodal stations. RESULTS: UVAM was significantly shorter and more lymph node specimens were obtained than with VAM. There was one case of fatal bleeding and two cases of right recurrent laryngeal nerve injury in the VAM group, and no postoperative complications in the UVAM group. CONCLUSIONS: When used with cervical VAM, ultrasound guidance assists physicians assess the space between lymph nodes, surrounding tissues, and large vessels systematically, making biopsy safer and easier, improving lymph node sampling, and decreasing postoperative complications. Furthermore, surgeons can easily learn and master this method. KEY POINTS: Significant findings of the study: Ultrasound was used in combination with cervical mediastinoscopy and the results showed that ultrasound guidance makes biopsy in patients safer and easier, improves lymph node sampling, and decreases postoperative complications. WHAT THIS STUDY ADDS: Surgeons can easily learn and master this method.

Use of intravoxel incoherent motion imaging to monitor a rat kidney chronic allograft damage model.

BACKGROUND: Chronic allograft damage (CAD) is the leading cause of long-term graft dysfunction. A noninvasive method that can diagnose CAD early and monitor its development is needed. METHODS: Kidneys from Fisher rats were transplanted into Lewis rats to establish a CAD model (n = 20). The control group underwent syngeneic kidney transplantation (n = 20). The serum creatinine of the rats was monitored. At 4, 12, and 20 weeks after modeling, a magnetic resonance imaging (MRI) examination was performed. The apparent diffusion coefficient (ADC), pseudo diffusion coefficient (D*), true diffusion coefficient (D) and perfusion fraction (f) of the two groups were analyzed. Chronic allograft damage index (CADI) scoring was used to evaluate the transplanted kidney specimens. Immunohistochemistry was used to detect the expression of fibrosis markers in the transplanted kidney tissues and to analyze their correlations with all MRI parameters. RESULTS: The transplanted kidneys in the experimental group developed CAD changes before the appearance of elevated creatinine. The MRI parameters in the experimental group [ADC (1.460 ± 0.109 VS 2.095 ± 0.319, P < 0.001), D (1.435 ± 0.102 VS 1.969 ± 0.305, P < 0.001), and f (26.532 ± 2.136 VS 32.255 ± 4.013, P < 0.001)] decreased, and D* (20.950 ± 2.273 VS 21.415 ± 1.598, P = 0.131) was not significantly different from those in the control group. ADC, D and f were negatively correlated with the CADI and the α-SMA and vimentin expression levels. CONCLUSION: Intravoxel incoherent motion (IVIM) imaging could detect CAD earlier than creatinine and reflect the degree of fibrosis in grafts quantitatively.

Use of Contrast-Enhanced Ultrasonography to Evaluate Chronic Allograft Nephropathy in Rats and Correlations between Time-Intensity Curve Parameters and Allograft Fibrosis.

This study quantitatively analyzed changes in the hemodynamic characteristics of renal allografts at different stages in a rat chronic allograft nephropathy (CAN) model as well as the relationship between hemodynamic parameters and renal allograft fibrosis using contrast-enhanced ultrasonography (CEUS). The experimental group used a CAN rat model (n = 30), and the control group used an orthotopic syngeneic renal transplant model (n = 30). After surgery, creatinine clearance rates were regularly monitored every 2 wk. The checking times were set at 4, 12 and 24 wk after surgery, which represent early, middle and late stage of CAN, respectively. At different stages of CAN, eight rats from each group were randomly selected for CEUS examination. Time-intensity curve (TIC) parameters, including rise time, peak intensity, mean transit time, area under the curve, wash-in slope, time-to-peak and α-smooth muscle actin (α-SMA) expression; Vimentin expression; and chronic allograft damage index scores were evaluated by linear correlation analysis. Before the creatinine clearance rate showed significant abnormalities, the renal allografts in the experimental group had already presented pathologic changes associated with CAN. In the early stage after surgery, compared to the TIC curve of the control group, the experimental group showed increased rise time, mean transit time, area under the curve and time-to-peak, and decreased wash-in slope (p < 0.05). Chronic allograft damage index scores and the expression levels of α-SMA and Vimentin proteins in renal allografts were correlated with TIC parameters (p < 0.05). Compared to creatinine clearance rate, CEUS can detect CAN at earlier stages. The correlations between TIC-related parameters and the expression levels of α-SMA and Vimentin in renal allografts indicate that CEUS is a feasible way to assess the degree of renal allograft fibrosis quantitatively.

The Prevalence and Association of Varicoceles on Male Patients With Benign Prostatic Hyperplasia/Lower Urinary Tract Symptoms.

OBJECTIVE: To investigate the association between the prevalence of varicocele and benign prostatic hyperplasia (BPH)/lower urinary tract symptoms (LUTS) in elder man in China. METHODS: A total of 831 BPH/LUTS outpatients who were 40 years or older were recruited. The patients' age, total prostatic volume (TPV), International Prostate Symptom Score, total prostate-specific antigen, nocturia, and body mass index were recorded. The presence and grade of varicocele were diagnosed by physical examination in combination with scrotal color Doppler. RESULTS: The total prevalence of varicocele was 53.0%. The prevalence values of varicoceles in patients were 40-49, 50-59, 60-69, 70-79 years old, and 80 or above were 43.0%, 42.4%, 54.0%, 59.5%, and 64.0%, respectively. When comparing with varicocele grade, TPV (P = .002) was found to be significantly different. Nocturia frequencies increased significantly in patients with varicocele (P < .01). There were no difference in terms of International Prostate Symptom Score, total prostate-specific antigen, and body mass index between patients with no varicocele and with grades 1, 2, and 3 varicoceles (P > .05). CONCLUSION: For elderly patients, the prevalence of varicocele shows an increasing trend with aging. Higher-grade varicoceles are associated with higher TPV and nocturia levels. Varicocele, which may be a factor that affects BPH/LUTS, cannot be overlooked.

Renal Doppler and Novel Biomarkers to Assess Acute Kidney Injury in a Swine Model of Ventricular Fibrillation Cardiac Arrest.

BACKGROUND: Majority of the research on cardiac arrest (CA) have focused on post-CA brain injury and myocardial dysfunction, the renal dysfunction and acute kidney injury (AKI) in other critical illnesses after CA have not been well described. This study was designed to assess AKI with renal Doppler and novel AKI biomarkers in a swine model of ventricular fibrillation cardiac arrest (VFCA). METHODS: Thirty healthy piglets were divided into VFCA group (n = 22) and Sham group (n = 8) in a blinded manner. Mean arterial pressure, heart rate, and cardiac output were recorded continuously. Cardiac arrest (CA) was induced by programmed electric stimulation in the VFCA group, and then cardiopulmonary resuscitation was performed. Twenty piglets returned of spontaneous circulation (ROSC) and received intensive care. Blood and urine samples were collected for AKI biomarkers testing, and Color Doppler flow imaging was performed at baseline, 6 h, 12 h, and 24 h, respectively after ROSC. At ROSC 24 h, the animals were sacrificed and a semi-quantitative evaluation of pathologic kidney injury was performed. RESULTS: In the VFCA group, corrected resistive index (cRI) increased from 0.47 ± 0.03 to 0.64 ± 0.06, and pulsatility index (PI) decreased from 0.82 ± 0.03 to 0.68 ± 0.04 after ROSC. Cystatin C (CysC) in both serum and urine samples increased at ROSC 6 h, but neutrophil gelatinase-associated lipocalin (NGAL) in serum increased to 5.34 ± 1.68 ng/ml at ROSC 6 h, and then decreased to 3.16 ± 0.69 ng/ml at ROSC 24 h while CysC increasing constantly. According to the renal histopathology, 18 of 20 animals suffered from kidney injury. The grade of renal injury was highly correlated with RI, cRI, NGAL, and CysC. Linear regression equation was established: Grade of renal injury = 0.002 × serum CysC + 6.489 × PI + 4.544 × cRI - 8.358 (r2 = 0.698, F = 18.506, P < 0.001). CONCLUSIONS: AKI is common in post-CA syndrome. Renal Doppler and novel AKI biomarkers in serum and urine are of significant importance as early predictors of post-CA AKI.

Assessment of postoperative perfusion with contrast-enhanced ultrasonography in kidney transplantation.

The aim of this study was to use contrast-enhanced ultrasound (CEUS) to evaluate renal perfusion after kidney transplantation and investigate the clinical significance of CEUS in monitoring postoperative renal perfusion. Thirty-five patients who underwent kidney transplantations were included in this study and divided into two groups-normal and abnormal-based on their serum creatinine (SCr) levels. Conventional ultrasound and CEUS were used to monitor renal perfusion after kidney transplantation. The differences in the results between the two groups were then compared. Color doppler ultrasonography showed that there were significant differences in the resistance index (RI) and the pulsatility index (PI) of the interlobar artery between the groups. Furthermore, CEUS indicated a significant difference between the two groups regarding the slope rate of the cortical ascending curve (A1), the medullary ascending curve (A2), and the derived peak intensity (DPI1). CEUS precisely showed the characteristics of microcirculation in renal parenchyma after kidney transplantation. It also detected changes in the microcirculation, which was a new method of evaluating tissue perfusion in transplanted kidneys.

Application of laparospic ultrasonography in surgery of small renal cell carcinoma.

PURPOSE: : To assess the clinic value of application of laparospic ultrasonography (LU) in partial nephrectomy of small renal cell carcinoma. MATERIALS AND METHODS: From 2007 to 2011, 28 small renal cell carcinoma patients in ou clinic underwent laparoscopic partial nephrectomy with LU. For comparison with preoperative conventional ultrasound and CT, we collected ultrasonic performance of the affected side kidney, renal tumor location, size, echo change, blood supply situation and the relationship with the surrounding tissue. RESULTS: LU could more clearly show the tumor interior structure and blood supply, as well as the relationship with the surrounding tissue. It also can provided doctor assistance with real-time tumor resection, reducing operative complications. CONCLUSIONS: LU can clearly show tumor internal structure and blood supply, which is helpful for explicit diagnosis. Moreover, it supplies accurate information for surgeons and assists surgery. Therefore LU has an important guiding value in partial nephrectomy for small renal cell carcinoma.

Comparison of ultrasound echo-tracking technology and pulse wave velocity for measuring carotid elasticity among hemodialysis patients.

This study aims to investigate the correlation between carotid elasticity in hemodialysis patients as evaluated by ultrasound echo-tracking technology and aortic pulse wave velocity. A total of 103 patients with end-stage renal disease who underwent stable hemodialysis were enrolled. An ultrasonic echo-tracking method was used to evaluate the elastic modulus and the stiffness index (ß), which were compared with pulse wave velocity (PWV). Blood glucose, blood lipids, and serum creatinine were also tested. These indices were analyzed to determine the independent factor for arterial elasticity. The carotid elastic modulus and ß were in good correlation with PWV among hemodialysis patients (P = 0.000). Diabetes and age are independent risk factors for arterial elasticity among hemodialysis patients. Ultrasound echo-tracking technology is a sensitive and accurate method for evaluating arterial elasticity and is a good alternative to traditional PWV.

Intraoperative ultrasonography: a useful tool in retrolaparoscopic nephron-sparing surgery.

OBJECTIVE: To evaluate the value of intraoperative laparoscopic ultrasonography (ILUS) in retrolaparoscopic nephron-sparing surgery. METHODS: A total of 81 cases were studied during a 5-year period: 38 patients with a benign renal tumor who underwent enucleation of the tumor and 43 patients with a suspected malignant renal tumor who underwent wedge resection of the tumor. ILUS was used to evaluate renal perfusion, locate the tumor, precisely delineate the tumor border, characterize the tumor, and look for any suspected satellite renal masses. RESULTS: All procedures were successful without conversion to open surgery. The mean operating time was 106 min for enucleation (range 70- 150 min) and 114 min for wedge resection (range 80- 235 min). The mean size of benign tumors was 4.02 cm and that of malignant tumors was 3.13 cm, and all margins were negative. An additional renal artery branch was detected in 11 patients. In 2 cases the operative procedure was changed based on the ILUS findings. No satellite lesion was found in any of the patients with malignant tumors. CONCLUSIONS: ILUS provides significant benefit in retrolaparoscopic nephron-sparing surgery. In a number of situations, especially endogenic lesions, it is an essential surgical tool.

Association of serum pentosidine with arterial stiffness in hemodialysis patients.

Pentosidine is an advanced glycation end product (AGE). The present study was undertaken to investigate the association of serum pentosidine with carotid distensibility as a measure of arterial stiffness in hemodialysis patients. One hundred and three patients on maintenance hemodialysis were recruited. The distensibility coefficient of the common carotid artery was evaluated by an ultrasonic phase-locked echo-tracking system. Serum pentosidine was measured by competitive enzyme-linked immunosorbent assay. Serum albumin, lipid profile, calcium, phosphorus, intact parathyroid hormone (iPTH), high-sensitivity C-reactive protein (hs-CRP), and oxidized low-density lipoprotein (ox-LDL) levels were also measured. Correlation was determined by linear and multiple stepwise regression analysis. Serum pentosidine level studied in hemodialysis patients was 0.54 +/- 0.13 microg/mL. No significant difference in serum pentosidine level was noted between patients with and without diabetes (0.59 +/- 0.10 microg/mL vs. 0.53 +/- 0.13 microg/mL, P = 0.062) as well as between patients with and without prior cardiovascular disease (CVD) history (0.56 +/- 0.14 microg/mL vs. 0.53 +/- 0.12 microg/mL, P = 0.206). In multivariate regression analysis, only age (beta = 0.363, P < 0.001) and ox-LDL (beta = 0.262, P = 0.004) were identified as independent determinants for serum pentosidine. Serum pentosidine was significantly correlated with carotid distensibility (r = -0.387, P < 0.001), as well as age, ox-LDL, and hs-CRP. After adjustment for age, blood pressure, history of diabetes, prior CVD history, lipid profile, calcium, phosphorus, iPTH, hs-CRP, and ox-LDL, serum pentosidine was still negatively correlated with distensibility (beta = -0.175, P = 0.044). Serum pentosidine was independently associated with carotid distensibility in hemodialysis patients. This finding suggested that the accumulation of AGE might be an important pathway in the development of arterial stiffness in end-stage renal disease.

Association between insulin resistance and carotid arterial stiffness in nondiabetic hemodialysis patients.

BACKGROUND: Patients with end-stage renal disease are known to have insulin resistance and advanced arterial stiffness. The present study was undertaken to investigate whether insulin resistance was correlated with carotid arterial stiffness in hemodialysis patients. METHODS: Eighty nondiabetic hemodialysis patients were recruited. Stiffness index beta of the common carotid artery was assessed by ultrasound using echo-tracking system. Insulin resistance was evaluated by the homeostasis model assessment method (HOMA-IR). Serum albumin, lipid profile, calcium, phosphorus, intact parathyroid hormone, high-sensitivity C-reactive protein and oxidized low-density lipoprotein (ox-LDL) were also measured. RESULTS: Patients with higher HOMA-IR levels had higher BMI, ox-LDL, and stiffness index beta than patients with lower HOMA-IR levels. HOMA-IR was independently correlated with stiffness index beta (beta = 0.260, p = 0.016). BMI and ox-LDL were independent contributors to HOMA-IR. CONCLUSION: Insulin resistance assessed by HOMA-IR is closely associated with carotid arterial stiffness in nondiabetic hemodialysis patients.