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

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.

Evaluation of a novel radial echoendosonoscope with a piezoelectric-composite transducer: An open-label, multicenter, randomized, parallel-group, noninferiority clinical trial

BACKGROUND AND OBJECTIVES

EUS is widely used in the clinical practice. This study aimed to evaluate the efficacy of a novel echoendoscope regarding image quality, maneuverability, stability of the entire machine system, and safety.

SETTING AND DESIGN

We conducted this open-label, multicenter, randomized, parallel-group, noninferiority clinical trial in three tertiary hospitals between November 2018 and April 2019.

SUBJECTS AND METHODS

One hundred and thirty patients were included. The stratified segment randomization method was employed. Sixty-five patients in the test group received an EUS examination using the new material radial echoendoscope, and 65 patients in the control group received an EUS examination using the existing endoscope. We recorded the image quality, maneuverability, stability of the entire machine system, and safety. For the main outcome, comprehensive image quality, the groups were compared with the noninferiority test, using the confidence interval method and 10% as the noninferiority threshold. The Pearson Chi-square test was used to compare the incidence of adverse events between the groups.

RESULTS

Sixty-five patients in the test group and 63 patients in the control group were analyzed. Two patients in control group did not complete an EUS examination due to machine problems. There were no significant differences in image quality, maneuverability of the echoendoscope, stability of the entire machine system, and safety between the groups.

CONCLUSIONS

This new material radial echoendoscope showed good capabilities for image quality, maneuverability, stability of the entire machine system, and safety. Our data suggest that the new echoendoscope may provide an additional option for endoscopic physicians.

Evaluation of Intravascular Ultrasound Catheter-Based Transducers Using the Resolution Integral

Intravascular ultrasound (IVUS) catheters are a specialist imaging modality used in the assessment of cardiovascular disease. The ultrasound transducer may either be of single-element mechanical or phased-array design. Because of their design and operating frequencies (10-45 MHz), evaluation of the imaging performance is not possible with commercially available ultrasound test objects. An existing test object, the Edinburgh Pipe Phantom, was modified to allow measurement of resolution integral (R), depth of field (Lr) and characteristic resolution (Dr) of IVUS catheters. In total, seven IVUS catheters, from two manufacturers and of both single-element mechanical and phased-array design, were tested to provide a measure of performance over different frequencies and technologies. Measurements of R for the tested IVUS catheters ranged from 11.9 to 18.8. The modified Edinburgh Pipe Phantom therefore allows catheter-based ultrasound probes to be evaluated scientifically and their performance to be seen in relation to other similar ultrasound technologies such as pre-clinical ultrasound and endoscopic ultrasound.

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.

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.