Scott Inglis

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.

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.

PTH-027 Review of faults and usage of two upper and lower gastrointestinal endoscopes suppliers in nhs lothian over a 40 month period

Introduction Endoscopes are used for diagnostic and therapeutic applications in Gastroenterology (GI). The nature of these procedures, can subject endoscopes to hard use and stringent cleaning and decontamination procedures, leading to numerous faults developing over their lifespan. The aim was to review the service history of two upper and lower GI endoscopes suppliers within NHS Lothian, and usage, over a 40 month period. Method The service history of each GI endoscope owned by NHS Lothian was requested from each supplier’s service department, between January 2011 and April 2014. Usage data for each endoscope with a repair was extracted from the Endoscopy Reporting System (Unisoft). Each repair was reviewed and classified as either an angulation, damage, leak, blockage, image, electrical, or other fault. The fault and corresponding usage was split by type and supplier to calculate average number of repairs, usage and give a measure of reliability (average repairs per annum/average procedure per annum). A chi square was performed to see if there were significant differences between fault categories from each supplier. A p < 0.05 was classed as significant. Results The results obtained from the analysis of the faults from supplier A and supplier B were: Angulation 2 and 4.4% (p = 0.10), Damage 9.3 and 6% (p = 0.15), Blockages 17.7 and 20% (p = 0.49), Image faults 21and 29.6% (p = 0.02), Leaks 40.7 and 22.4% (p < 0.001), electrical failures 3.7and 13.2% (p < 0.001) and other of 5.7 and 4.4% (p = 0.50) respectively. A summary of the number of scopes, procedures and repairs from both suppliers are shown in Table 1.Abstract PTH-027 Table 1 Summary of scope and procedure numbers used within this study and analysis of repairs and usage per scope supplier and type. Supplier Scope type No. of repairs (40 mo) No. of scopes Total usage (42 mo) Ave. proc/scope p.a. Ave. repairs p.a. Annual repair per scope Reliability A Upper 120 43 17889 119 40 0.93 0.34 Lower 180 37 29427 227 55 1.62 0.26 Total 300 80 47316 346 100 2.55 0.29 B Upper 155 25 15208 174 55 2.2 0.32 Lower 95 17 5476 92 27 1.61 0.3 Total 250 42 20684 266 82 3.81 0.31 Conclusion A comprehensive registry of endoscopes with individual repair profiles can give extremely valuable information regarding endoscope reliability and durability. This ensures that hardware quality is maintained. It can facilitate the replacement process as well as help in the negotiation of maintenance contracts. Modern endoscopes in general are of similar high quality and have similar repair profiles. There are individual company differences in terms of vulnerable parts for different scopes but in general choice of endoscopes should be based on existing facilities, unit case mix and cost rather than on individual brand names. Disclosure of interest S. Inglis: None Declared, N. Kennedy: None Declared, J. Plevris Grant/ Research Support from: JN Plevris has received funding from Fujifilm in the past for endoscopic research.

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.

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.

PWE-197 Optimisation of the FICE technique for enhancement of oesophageal pathology

Introduction Fuji Intelligent Chromo Endoscopy (FICE) is a post-processing image enhancement technique designed by Fuji for their video endoscopy systems. FICE is a method that takes the original white light image and separates the image into discrete light wavelengths, each setting has a different combination of three selected wavelengths (from 400 to 700 nm), representing RGB, that are independently weighted, combined and superimposed on the white light image to produce the FICE image. Fuji currently provides 10 different settings. The aims of this project are: to evaluate the current FICE settings on images captured during upper GI endoscopy, and the creation of new oesophageal settings to simplify the selection and improve the application of FICE in the diagnosis of oesophageal pathology. Methods We used a PC based FICE simulator, provided by Fuji, to process images offline, using the FICE settings. A series of images were captured during diagnostic endoscopies of various conditions (eg, varicies, Barretts oesophagus) at various points in the oesophagus using the capture facilities on the Fuji endoscopy EPX-4400 processor. Using the FICE simulator, two new FICE settings were created to maximise the enhancement of the pathology while maintaining the anatomical colouring. For each RGB component, the selected wavelength was altered independently in 5 nm steps. Once the wavelength was fixed, the gain was altered to minimise artefacts and maximise enhancement. Forty images were selected from the series that covered various conditions, and were processed via the FICE simulator using the 10 standard and two new settings. The images were randomised for evaluation by five blinded endoscopists. Each endoscopist compared the original and FICE image and scored the degree of enhancement over the original image from 0 (no enhancement) to 5 (maximum). The highest score FICE settings were translated to the EPX-4400 processor for further clinical evaluation. Results The oesophageal mucosa presented with two distinct shades of pink (eg, Light and Dark). Two settings were created, one for each mucosal shade (L1—Light and L2—Dark). From the 40 images 65% would be characterised as Light and 35% Dark mucosa. Out of a possible enhancement score of 1000, the standard FICE Settings (0–9) scored between 202 and 319, with settings 2 scoring the highest (319). The Lothian FICE settings L1 and L2 scored 463 and 387 respectively. Conclusion In conclusion the L1/2 FICE settings were found to provide further enhancement compared with current FICE settings by improving the colour discrimination between normal and abnormal mucosa. FICE is a useful and flexible system with a lot of potential but still requires optimisation. Competing interests S Inglis Grant/Research Support from: Fuji provided software for Trial, S Alexandridis Grant/Research Support from: Fuji/Imotech Medical Provided funding for a Fellowship, J Plevris Grant/Research Support from: Fuji Provided Loan Equipment for trial.