There have been reports on the use of Ultrasound (US) for monitoring fracture repair
and for measuring muscle volume. Change in muscle mass is a useful bio-marker for
monitoring the use and disuse of muscle, and the affects of age, disease and injury.
The main modality for imaging bone is X-ray and for muscle volume Magnetic
Resonance (MR). Previous studies have shown US to have advantages over X-ray
and MR. US can image all stages of the fracture repair process and can detect signs
of healing 4-6 weeks before X-ray allowing earlier detection of possible
complications. Compared to MR, US is less resource intensive, easier to access and
also has fewer exclusion criteria for patients.
Despite these advantages, the limited field of view that US can provide results in
high operator dependency for scan interpretation and also for length and volume
measurements.
Three-dimensional Ultrasound (3D US) has been developed to overcome these
limitations and has been used to provide extended field of view images of the foetus
and the heart and to obtain accurate volume measurements for organs.
In this thesis it is hypothesized that 3D US can provide a more comprehensive
method of imaging fracture repair than X-ray and is also a viable alternative to MR
for determining muscle volumes in vivo.
Initially, an electromagnetically (EM) tracked 3D US system was evaluated for
clinical use using phantom-based experiments. It was found that the presence of
metal objects in or near the EM field caused distortion and resulted in errors in the
volume measurements of phantoms of up to ±20%. An optically tracked system was
also evaluated and it was found that length measurements of a phantom could be
made to within ±1.3%.
Fracture repair was monitored in five patients with lower limb fractures. Signs of
healing were visible earlier on 3D US with a notable, although variable, lag between
callus development on X-ray compared to 3D US. 3D US provided a clearer view of
callus formation and the changes in density of the callus as it matured. Additional
information gained by applying image processing methods to the 3D US data was used to develop a measure of callus density and to identify the frequency dependent
appearance of the callus.
Volume measurements of the rectus femoris quadricep muscle were obtained
using 3DUS from eleven healthy volunteers and were validated against volume
measurements derived using MR. The mean difference between muscle volume
measurements obtained using 3D US and MR was 0.53 cm3 with a standard
deviation of 1.09 cm3 and 95% confidence intervals of 0.20 - 1.27 cm3
In conclusion, 3D US demonstrates great potential as a tool for imaging
components of the musculoskeletal system and as means of measuring callus density
