Ultrasonic echo analysis in the investigation of soft tissue motion
The motion of tissues within the human body can be
investigated by a number of techniques, including ultrasonic
echography. The ultrasonic echo patterns from
regions of relatively homogeneous tissue bear an ambiguous
relationship to their spatial structure, preventing the
use of an lmaging system to study the motion of such
tissue. This work describes the development and use of a
method of analysing the ultrasonic echoes from tissue to
investigate their motion.
The properties of the echoes from tissue are studied
using a theoretical model, and a number of methods of
analysing the echoes are suggested. The theoretical model
can also be used to simulate the ultrasonic imaging of such
The apparatus for obtaining and analysing the echoes
from tissues is described, with an investigation of the
errors involved in the digitisation of analogue signals.
The methods of echo analysis proposed for the study of
tissue motion are evaluated experimentally, using specimens
of fixed liver, and the results show that a correlation
method of analysis provides the most consistent measure of
This method is applied to the analysis of the in vivo
motion of soft tissue. The majority of measurements are
taken on the livers of normal subjects, with a simultaneous
recording of the electrocardiograph. The amplitude, frequency
and phase of the motion are measured and the results
correlated with the electrocardiograph.
The conclusions from this work are that the stochastic
properties of the ultrasonic echoes from soft tissues
require the use of statistical methods of analysis to study
successfully tissue motion. Estimates are made of the
extent to which the phenomenon of tissue motion can be used
in the characterisation of the pathological state of tissue.