4 research outputs found
Development of a freehand three-dimensional radial endoscopic ultrasonography system
Oesophageal cancer is an aggressive malignancy with an overall five-year survival of 5-10% and
two-thirds of patients have irresectable disease at diagnosis. Accurate staging of oesophageal cancer is
important as survival closely correlates with the stage of the tumour, nodal involvement and presence
of metastases (TNM staging). Endoscopic ultrasonography (EUS) is currently the most reliable
modality for providing accurate T and N staging. Depending on findings of the staging, various
treatment options including endoscopic, oncological, and surgical treatments may be performed.
It was theorised that the development of three-dimensional radial endoscopic ultrasonography would
reduce the operator dependence of EUS and provide accurate dimensional and volume measurements
to aid planning and monitoring of treatment. This thesis investigates the development of a three
dimensional endoscopic ultrasound technique that can be used with the radial echoendoscopes.
Various agar-based tissue mimicking material (TMM) recipes were characterised using a scanning
acoustic macroscope to obtain the acoustic properties of attenuation, backscatter and speed of sound.
Using these results, a number of endoscopic ultrasound phantoms were developed for the in-vitro
investigation and evaluation of 3D-EUS techniques.
To increase my understanding of EUS equipment, the imaging and acoustic properties of the EUS
endoscopes were characterised using a pipe phantom and a hydrophone. The dual ‘single element’
mechanical and ‘multi-element’ electronic echoendoscopes were investigated. Measured imaging
properties included dead space, low contrast penetration, and pipe length. The measured acoustic
properties included transmitted beam plots, active working frequency and peak pressures.
Three-dimensional ultrasound techniques were developed for specific application to EUS. This
included the study of positional monitoring systems, reconstruction algorithms and measurement
techniques. A 3D-EUS system was developed using a Microscribe positional arm and frame grabber
card, to acquire the 3D dataset. A Matlab 3D-EUS toolbox was written to reconstruct and analyse the
volumes. The 3D-EUS systems were evaluated on the EUS phantom and in clinical cases.
The usefulness of the 3D-EUS systems was evaluated in a cohort of patients, who were routinely
investigated by conventional EUS for a variety of upper gastrointestinal pathology. 3D-EUS
accurately staged early tumours and provided the necessary anatomical information to facilitate
treatment. With regards to more advanced tumours, 3D-EUS was more accurate than EUS in T and N
staging. 3D-EUS gave useful anatomical details in a variety of benign conditions such as varicies and
GISTs