A method of noninvasively measuring a biomechanical parameter of soft biological tissue, wherein the biomechanical parameter comprises one or more of natural oscillation frequency, dynamic stiffness, logarithmic decrement, mechanical stress relaxation time, Deborah number and coefficient of resilience, using an impulse applying device comprising a movable testing body having an end portion to be placed in contact with a surface of the tissue and a rotary actuator, the method comprising a pre-measurement process which comprises:
- the impulse applying device applying a pre-pressure to the surface of the tissue via the end portion in contact with the surface of the tissue;
- whilst maintaining said pre-pressure, the impulse applying device generating, by the rotary actuator, at least two impulses separated by a time interval, each impulse causing the end portion to impart to the tissue an action with certain parameters, and each of the end portion actions inducing a response of the tissue;
- calculating a value of the biomechanical parameter of the tissue from the response induced by each end portion action, wherein the biomechanical parameter comprises at least dynamic stiffness;
- and
- calculating if the value of the biomechanical parameter calculated from the response induced by each end portion action are sufficiently similar to each other to indicate that the pre-pressure, the parameters of each end portion action and the time interval are acceptable for a measurement process to be conducted on the surface of the tissue using the same pre-pressure, a plurality of end portion actions with the same parameters and the same time interval,
- wherein, if the determination is that the pre-pressure, the parameters of each end portion action and the time interval are not acceptable for the measurement process to be conducted using the same pre-pressure, parameters of each end portion action and time interval, the method further comprises a subsequent pre-measurement process which comprises:
- the impulse applying device applying to the surface of the tissue a subsequent pre-pressure, and whilst maintaining said subsequent pre-pressure, generating at least two subsequent impulses separated by a subsequent time interval each to cause the end portion to impart to the tissue a subsequent end portion action, at least one of the subsequent pre-pressure, the parameters of each subsequent end portion actions and the subsequent time interval being modified;
- calculating the value of the biomechanical parameter of the tissue from the response induced by each subsequent end portion action;
- and
- calculating if the value of the biomechanical parameter determined from the response induced by each subsequent end portion action are sufficiently similar to each other to indicate that the subsequent pre-pressure, the parameters of each subsequent end portion action and the subsequent time interval are acceptable for the measurement process to be conducted on the surface of the tissue using the same subsequent pre-pressure, a plurality of end portion actions with the same parameters as the subsequent end portion actions, and the same time interval as the subsequent time interval,
- wherein the pre-measurement process further comprises:
- for each of the end portion actions, calculating the value of the dynamic stiffness of the tissue to obtain a plurality of values of dynamic stiffness each corresponding to a respective end portion action;
- and
- said calculating if the plurality of values of dynamic stiffness calculated from the response induced by each end portion action are sufficiently similar being done by performing a statistical analysis to determine a variation of the plurality of values of dynamic stiffness.