The Imaging Performance of Diagnostic Ultrasound Scanners Using the Edinburgh Pipe Phantom to Measure the Resolution Integral - 15 Years of Experience.

The grayscale imaging performance of a total of 368 different scanner/transducer combinations from 39 scanner manufacturers measured over a period of 15 years is presented. Performance was measured using the resolution integral, a single figure-of-merit to quantify ultrasound imaging performance. The resolution integral was measured using the Edinburgh Pipe Phantom. Transducers included single element, linear, phased, curvilinear and multi-row arrays. Our results demonstrate that the resolution integral clearly differentiates between transducers with varying levels of performance. Two further parameters were also derived from the resolution integral: characteristic resolution and depth of field. We demonstrate that these two parameters can successfully characterize individual transducer performance and differentiate between transducers designed for different clinical and preclinical applications. In conclusion, the resolution integral is an effective metric to quantify and monitor grayscale imaging performance in clinical practice.

An Assessment of the Imaging Performance of Hand-Held Ultrasound Scanners Using the Edinburgh Pipe Phantom.

OBJECTIVE: Although hand-held ultrasound devices (HHUSDs) are currently used for a diverse range of diagnostic and interventional applications the imaging performance of such scanners is rarely considered. The aim of this study was to assess the imaging performance of a wide-range of HHUSDs and compare their imaging performance to cart-based systems utilized for the same clinical applications. METHODS: The grayscale imaging performances of 19 HHUSDs from eight different manufacturers, manufactured between 2016 and 2021, were measured using a figure-of-merit known as the resolution integral. The imaging performance of the HHUSDs were compared to 142 cart-based ultrasound scanners. RESULTS: The HHUSD with the overall highest resolution integral (66) was a Butterfly (Burlington, MA, USA) wired phased array for small parts applications, followed by a Philips (Bothell, WA, USA) Lumify wired curvilinear transducer (57) for abdominal applications, a Butterfly wired phased array (56) for abdominal applications, a GE (Freiburg, Baden-Wurttemberg, Germany) VScan Air wireless linear array (56) for small parts applications, and a Healcerion (Seoul, Korea) Sonon 300L wireless linear array (56) for small parts applications. A GE VScan Extend wired phased array had the highest resolution integral (44) for cardiac applications. CONCLUSIONS: The Butterfly phased array had the highest resolution integral of all the 19 HHUSDs, although this value is still less than the majority of cart-based cardiac and abdominal ultrasound scanners manufactured from 2010 to 2017. Clinical users of HHUSDs should be mindful of the limitations in imaging performance of hand-held ultrasound devices.

Adaptive Manufacturing for Healthcare During the COVID-19 Emergency and Beyond.

During the COVID-19 pandemic, global health services have faced unprecedented demands. Many key workers in health and social care have experienced crippling shortages of personal protective equipment, and clinical engineers in hospitals have been severely stretched due to insufficient supplies of medical devices and equipment. Many engineers who normally work in other sectors have been redeployed to address the crisis, and they have rapidly improvised solutions to some of the challenges that emerged, using a combination of low-tech and cutting-edge methods. Much publicity has been given to efforts to design new ventilator systems and the production of 3D-printed face shields, but many other devices and systems have been developed or explored. This paper presents a description of efforts to reverse engineer or redesign critical parts, specifically a manifold for an anaesthesia station, a leak port, plasticware for COVID-19 testing, and a syringe pump lock box. The insights obtained from these projects were used to develop a product lifecycle management system based on Aras Innovator, which could with further work be deployed to facilitate future rapid response manufacturing of bespoke hardware for healthcare. The lessons learned could inform plans to exploit distributed manufacturing to secure back-up supply chains for future emergency situations. If applied generally, the concept of distributed manufacturing could give rise to "21st century cottage industries" or "nanofactories," where high-tech goods are produced locally in small batches.

Inactivation of Ascaris suum in a biodrying compost system.

Pathogen contamination of waterways is a serious concern in dairy farming areas where livestock waste is applied to agricultural fields. As an alternative, a biodrying composting system dries collected livestock waste, reduces the strong odors, and has been proposed as a means of reducing, and even eliminating pathogens present in the waste. Therefore, the survival of pathogens in a biodrying composting system was investigated. Dairy farm livestock waste was piled in a biodrying storage shed where forced aeration and natural decomposition processes heated a major portion of the waste pile to temperatures exceeding 55 degrees C. Ascaris suum eggs were used as the surrogate species and inoculated into special chambers and placed at three different elevations at different intervals along the length of the pile. Control chambers were stored in water at 4 degrees C in the laboratory. Both compost and control chambers were removed at Day 4, 8, 12, 16, and 20. The eggs were extracted from the chamber medium and analyzed for viability. No viable eggs were recovered from any of the chambers removed from the compost pile, while >or=90% viability was observed in the control chambers. High temperatures and continued drying were the major contributing factors to the inactivation of the helminth eggs. The complete inactivation of A. suum eggs by the biodrying process encourages the storage and treatment of manure to high temperatures and reduced moisture conditions before field spreading to reduce the risk of harmful pathogens contaminating waterways and potential drinking water supplies.

An anthropomorphic tissue-mimicking phantom of the oesophagus for endoscopic ultrasound.

This study details the design and construct of an anthropomorphic phantom of the oesophagus suitable for use with endoscopic ultrasound (EUS) and 3-D volume measurements. The phantom was constructed using agar-based tissue-mimicking material (TMM) of different acoustical properties to simulate various anatomical and pathologic features. The acoustical properties were measured with a scanning acoustical macroscope. An Olympus GF-UM200 echo-endoscope and digital position measurement arm were used to scan the phantom at 7.5 and 12 MHz. Comparative dimensional measurements were performed on the phantom via 2-D and 3-D EUS. TMM attenuation varied between 0.1 and 0.5 dB/cm.MHz. Backscatter power, relative to normal TMM, was from 0 to -12.2 dB, with an average speed of sound of 1537 +/- 1.9 m/s. Measurements of objects within the phantom by 2-D and 3-D EUS had mean errors of 8% and 2.2%, respectively. The construction of the anthropomorphic EUS phantom facilitated EUS training and research and development studies.

Detecting failed elements on phased array ultrasound transducers using the Edinburgh Pipe Phantom.

AIMS: Imaging faults with ultrasound transducers are common. Failed elements on linear and curvilinear array transducers can usually be detected with a simple image uniformity or 'paperclip' test. However, this method is less effective for phased array transducers, commonly used in cardiac imaging. The aim of this study was to assess whether the presence of failed elements could be detected through measurement of the resolution integral (R) using the Edinburgh Pipe Phantom. METHODS: A 128-element paediatric phased array transducer was studied. Failed elements were simulated using layered polyvinyl chloride (PVC) tape as an attenuator and measurements of resolution integral were carried out for several widths of attenuator. RESULTS: All widths of attenuator greater than 0.5 mm resulted in a significant reduction in resolution integral and low contrast penetration measurements compared to baseline (p < 0.05). CONCLUSIONS: Measurements of resolution integral and low contrast penetration both have the potential to be used as straightforward and inexpensive tests to detect failed elements on phased array transducers. Particularly encouraging is the result for low contrast penetration as this is a quick and simple measurement to make and can be performed with many different test objects, thus enabling 'in-the-field' checks.

Quality assurance testing of transoesophageal echocardiography probes.

INTRODUCTION: In response to an ultrasound imaging issue with transoesophageal echocardiography probes, a testing protocol was developed to check features pertinent to the operation of these probes. The imaging problem was detected in multiple probes of the same make and model. METHODS: Over a two-year period, a series of 26 probes of this model were tested at acceptance, then three to six months later before being replaced due to a defect. A range of visual, mechanical and electrical tests were performed. Image tests comprised low-contrast penetration measurements and a comparison of phantom images at regular intervals to highlight artefacts in both B-mode and colour Doppler imaging. RESULTS: Of the 26 defective probes replaced, 7 suffered mechanical/electrical problems, 5 of which prevented imaging results being obtained. Low-contrast penetration reduction of greater than 5% occurred in 14 probes. B-mode artefacts were observed on 12 probes and Doppler noise artefacts on 6 probes. No faults were found on five probes. The manufacturer addressed the imaging problem identified and of the seven subsequent probes supplied, only one suffered an imaging fault. CONCLUSIONS: The implementation of a quality assurance protocol for transoesophageal echocardiography probes resulted in cost savings on replacements/repairs. When provided with the evidence gathered, the manufacturer supplied 23 probes under warranty or as loan equipment. The regular testing of the probes substantially reduced the impact of downtime and poor diagnosis from this equipment on the clinical service.

Classification of arterial plaque by spectral analysis in remodelled human atherosclerotic coronary arteries.

We aimed to characterise and to identify the predominant plaque type in vivo using unprocessed radiofrequency (RF) intravascular ultrasound (US) backscatter, in remodelled segments of human atherosclerotic coronary arteries. A total of 16 remodelled segments were identified using a 30-MHz intravascular ultrasound (IVUS) scanner in vivo. Of these, 9 segments were classified as positively remodelled (>1.05 of the total vessel area in comparison with the proximal and distal reference segments) and 7 as negatively remodelled (<0.95 of reference segment area). Spectral parameters (maximum power, mean power, minimum power and power at 30 MHz) were determined and plaque type was defined as mixed fibrous, calcified or lipid-rich. Positively remodelled segments had a larger total vessel area (16.5 +/- 1.1 mm2 vs. 8.7 +/- 0.9 mm2, p<0.01) and plaque area (7.3 +/- 1.1 mm2 vs. 4.4 +/- 0.8 mm2, p=0.05) than negatively remodelled segments. Both positively and negatively remodelled segments had a greater percentage of fibrous plaque (p<0.01) than calcified or lipid-rich plaque. Comparing positively and negatively remodelled segments, there was no significant difference between the proportion of fibrous, calcified or lipid-rich plaque. We have been able to characterise and to identify plaque composition in vivo in human atherosclerotic coronary arteries. Our data suggest that remodelled segments are predominantly composed of fibrous plaque, as identified by RF analysis, although plaque composition is similar, irrespective of the remodelling type.

The Resolution Integral - a tool for characterising the performance of diagnostic ultrasound scanners.

In this paper, we describe how the resolution integral can be used as a tool for characterising the grey-scale imaging of diagnostic ultrasound scanners. The definitions of resolution integral, characteristic resolution and depth of field are discussed in relation to grey-scale imaging performance, together with a method of measuring these parameters using the Edinburgh Pipe Phantom. We show how the characteristic resolution and depth of field can be used to quantify the differences between transducers designed for different applications and how they are useful in identifying and quantifying changes in the performance of individual transducers.

Assessing the imaging capabilities of radial mechanical and electronic echo-endoscopes using the resolution integral.

Over the past decade there have been significant advances in endoscopic ultrasound (EUS) technology. Although there is an expectation that new technology will deliver improved image quality, there are few methods or phantoms available for assessing the capabilities of mechanical and electronic EUS systems. The aim of this study was to investigate the possibility of assessing the imaging capability of available EUS technologies using measurements of the resolution integral made with an Edinburgh Pipe Phantom. Various radial EUS echo-endoscopes and probes were assessed using an Edinburgh Pipe Phantom. Measurements of the resolution integral (R), depth of field (LR) and characteristic resolution (DR) were made at all operating frequencies. The mean R value for Fuji miniprobes was 16.0. The GF-UM20 and GF-UM2000 mechanical radial scopes had mean R values of 24.0 and 28.5, respectively. The two electronic radial echo-endoscopes had similar mean R values of 34.3 and 34.6 for the Olympus GF-UE260 and Fujinon EG-530 UR scopes, respectively. Despite being older technology, the mechanical GF-UM2000 scope had superior characteristic resolution (DR), but could not compare with the depths of field (LR) delivered by the current generation of electronic radial scopes, especially at the standard operating frequencies of 7.5 and 12 MHz.

A novel three-dimensional endoscopic ultrasound technique for the freehand examination of the oesophagus.

This study details the development and evaluation of a freehand radial three-dimensional endoscopic ultrasound (3D-EUS) technique for use in the upper gastro-intestinal tract. It comprised of a commercial EUS system, a custom acquisition system to simultaneous acquire radial B-mode images and corresponding incremental changes in position of the scope as it was withdrawn and a custom 3D-EUS package written in Matlab™, to reconstruct and analyse the volume. This technique was evaluated using an EUS phantom with embedded objects of known dimensions and volumes and with clinical images acquired during routine cancer staging. For the phantom measurements, average Z-dimensional error was <1% and volume errors were 1.4% (volume(1) = 48930 mm(3)) and 4.5% (volume(2) = 5100 mm(3)). Application of this technique to EUS acquired clinical images produced excellent characterisation of oesophageal structures and accurate dimension and volume measurements. It also enabled the endoscopist to review "off-line" the EUS examination in case important information was missed.

Validation of endoscopic ultrasound measured flow rate in the azygos vein using a flow phantom.

Increase in flow rate within the azygos vein may be used as an indicator of the degree of liver cirrhosis. The aim of this study was to evaluate the error in measurement of flow rate using a commercial endoscopic ultrasound system, using a flow phantom that mimicked azygos vein depth, diameter and flow rate. Diameter was underestimated in all cases, with an average underestimation of 0.09 cm. Maximum velocity was overestimated, by 4 ± 4% at 50°, 11 ± 3% at 60° and 23 ± 7% at 70°. The increase in error with beam-vessel angle is consistent with the error as arising from geometric spectral broadening. Flow was underestimated by amounts up to 33%, and it is noted that the overestimation caused by geometric spectral broadening is in part compensated by underestimation of diameter. It was concluded that measurement of flow rate using a commercially available endoscopic ultrasound system is dependent on the beam-vessel angle, with errors up to 33% for typical vessel depths, diameter and beam-vessel angle.