Ultrasound

The impact of ultrasound (US) on membrane filtration and cleaning were studied and compared at various operating parameters of nominal pore sizes of 10 and 100 kDa membrane, trans-membrane pressure (TMP) of 100 and 140 kPa, and US frequencies of 20 kHz and 40 kHz. An average of 15%–20% increase of permeability was observed when US (20 kHz) was applied to assist membrane filtration on 10 kDa membrane and 100 kPa trans-membrane pressure (TMP). However, an insignificant improvement was observed in the case of larger pore size membrane at higher TMP (140 kPa). US also augmented the membrane cleaning process effectively. Lower frequency 20 kHz US exhibited a higher flux recovery (>90%) than the high frequency 40 kHz (59%) using the 10 kDa pore size membrane with US-assisted membrane cleaning. Important factors influencing optimization of US effectiveness lie heavily on its configuration and operation. The experimental results as supported with SEM images demonstrate that US-assisted filtration and cleaning are most effective when membrane pore size, US frequency, and TMP are lower.

Ultrasound of the shoulder is a powerful and accurate method for the examination of the rotator cuff, biceps mechanism and the synovium. This article describes the anatomy, standard examination technique, indications, pitfalls and potential errors. It lists suggested imaging algorithms for a range of shoulder pathology.

The present study investigates the possibility of the non-destructive prediction of the main quality indices of commercial eggs by calculating the ultrasound phase velocity within the egg material. The phase velocity of the ultrasound signal in the egg material was determined by analysing the recorded ultrasound signals using the Fast Fourier Transform. Three hundred commercial eggs (Boris Brown, 33 weeks age) from the first day of egg laying were purchased from a farm and divided in two groups. The first group was kept at the room temperature (22–25°C) and the second group was kept in a refrigerator (5°C). Every week, 25 eggs from both the room and the refrigerator were first submitted to the non-destructive ultrasound test at weekly basis at the room temperature. Immediately after testing, the air cell, the thick albumen heights, the Haugh unit and the yolk index of the eggs were also determined destructively for the comparison purposes. The results were analysed to find any possi...

In the nondestructive inspection of aerospace materials and structures, water-coupled ultrasonic inspection is often not desirable due to contamination and property alteration concerns. Examples include composite and foam structures in space applications and honeycomb sandwiches that cannot tolerate water ingression. For practical and operational reasons, water-coupled ultrasound is also not preferred for on-aircraft inspection in maintenance hangars. Non-contact, air-coupled ultrasonic transducers are therefore an attractive alternative for such applications. This paper describes our experience of using piezoceramic air-coupled transducers for flaw detection and repair evaluation of composite parts. The paper first discusses the basic principles of air-coupled ultrasonic measurement and laboratory tests of various materials and structures, followed by a description of a portable, manual, air-coupled ultrasonic scan system that allowed the use of air-coupled ultrasound in the field ...

Malfunction of permanent vascular accesses remains a cause of frequent and costly morbidity in patients receiving chronic hemodialysis (CHD). Several recommendations for routine monitoring of these permanent vascular accesses for incipient failure have been proposed. In this study, multiple indicators of incipient vascular access dysfunction, including "venous" and "arterial" pressures at serial blood flows (200 ml/min, 300 ml/min, and 400 ml/min), percent urea recirculation, Doppler ultrasound, and access blood flow by ultrasound dilution technique were simultaneously evaluated in a total of 220 vascular accesses in 170 chronic hemodialysis patients in two separate study periods (6 months apart). The rate of thrombosis was determined within the subsequent 12 weeks of each study period to assess the short-term predictive power of access thrombosis. During the period of follow-up, there were 34 thrombotic events in 172 polytetrafluoroethylene (PTFE) grafts and only one thrombotic event in 48 arterio-venous fistulas (AVF). Therefore, the statistical analysis was limited to the PTFE grafts. When grafts with thromboses were compared to those without thrombosis by univariate analysis, access blood flow measured either by ultrasound dilution technique (875 +/- 426 ml/min with thrombosis vs. 1193 +/- 677 ml/min without thrombosis, P = 0.001) or by Doppler ultrasound (762 +/- 420 ml/min with thrombosis vs. 1171 +/- 657 ml/min without thrombosis, P = 0.001) were significantly different in the two groups. There was good correlation (r = 0.79, P = 0.0001) between the blood flows determined by both techniques. The grade of stenosis determined by ultrasound was also a statistically significant predictor (P = 0.02). "Venous" and "arterial" pressures were numerically similar and were not statistically different between the accesses that did and those that did not thrombose. When multivariate analysis was used, there was a significantly increased risk of thrombosis only with decreasing access blood flow determined by ultrasound dilution techniques after adjusting for other confounding variables. When the average blood flow of all grafts (1134 ml/min) is considered as the reference access blood flow (relative risk of 1.0), the relative risk of a PTFE thrombotic event within the subsequent 12 weeks was 1.23 at a blood flow 950 ml/min, 1.67 at a blood flow of 650 ml/min and to 2.39 at a blood flow of 300 ml/min. In summary, access blood flow measured by either Dilution or Doppler is a reliable indicator of subsequent short-term thrombosis risk. Other proposed methods of evaluating access dysfunction were not useful in our patients. If simple to use, cost-effective devices to measure dialysis access blood flow become readily available, the measurement of access blood flow will likely become the method of choice for screening of PTFE vascular access dysfunction in hemodialysis patients.

Carotid artery intima–media thickness (IMT) is now widely used as a surrogate marker for atherosclerotic disease. Carotid IMT measured by ultrasound has been shown to be correlated with coronary artery disease as defined by angiography. However, the relation between carotid IMT and ...

Femoral artery pseudoaneurysm is a significant complication in patients undergoing diagnostic or therapeutic catheterisation. First choice treatment for pseudoaneurysm is freehand ultrasound guided compression repair, which is time consuming and uncomfortable for the patient and operator. To explore a mechanical compression device (FemoStop) as an alternative treatment for iatrogenic femoral artery pseudoaneurysm. Fourteen patients with pseudoaneurysm were considered for treatment with FemoStop after a brief freehand ultrasound guided compression repair to confirm the compressibility of the lesion. The FemoStop compression was applied for 20 minutes. The result was controlled with colour Doppler ultrasound, and a second cycle of 20 minutes followed if necessary. FemoStop compression was successful in 13 of the 14 patients. The mean compression time was 33 minutes (range, 20-60). The mean number of compression periods was 1.6 (range 1-3). FemoStop compression was successful in all 11...

Deep-seated tumors can be treated by minimally invasive interstitial ultrasound thermal therapy. A miniature transducer emitting high-intensity acoustic waves is placed in contact with the targeted area to induce local thermal necrosis. Accurate positioning of the probe and treatment monitoring must be achieved for the technique to be effective. A piezocomposite technology was used for obtaining both high-quality imaging and effective treatment with the same transducer. Prototypes were designed and built to be compatible with an endoscopic approach for treating cholangiocarcinomas in the biliary ducts. The transducer had dimensions of 2.5 x 7.5 mm(2), it was cylindrically focused at 10 mm and it was operated at a center frequency of 11 MHz. Transducer efficiency was measured at 71%, and the impulse response corresponded to an axial resolution of 0.2 mm. In-vitro tests were conducted on samples of pig liver in which lesions up to 10 mm in depth were induced. B-mode images were obtain...

Objective: despite recent advances in medical imaging, pre-operative evaluation of liver tumors, whether benign or malignant, is often lacking in accuracy and precision. With the development of surgical laparoscopy, the benefits of diagnostic laparoscopy have been combined with those of operative ultrasound. This article aims to describe the technique of laparoscopic ultrasound of the liver, and to define its applications

Over the last decades, especially during the COVID-19 pandemic period, lung ultrasound (LUS) gained interest due to multiple advantages: radiation-free, repeatable, cost-effective, portable devices with a bedside approach. These advantages can help clinicians in triage, in positive diagnostic, stratification of disease forms according to severity and prognosis, evaluation of mechanically ventilated patients from Intensive Care Units, as well as monitoring the progress of COVID-19 lesions, thus reducing the health care contamination. LUS should be performed by standard protocol examination. The characteristic lesions from COVID-19 pneumonia are the abolished lung sliding, presence of multiple and coalescent B-lines, disruption and thickening of pleural line with subpleural consolidations. LUS is a useful method for post-COVID-19 lesions evaluation, highlight the remaining fibrotic lesions in some patients with moderate or severe forms of pneumonia.