A quantitative stiffness assessment method in liver biopsy teleoperations

This paper reviews the study progress of existing liver fibrosis assessment methods. After reviewing, this paper proposes a method to assess stiffness which intends the fibrosis, in the liver biopsy teleoperations. In this method, the liver biopsy operation is modeled. Also, teleoperated liver biopsy operations are conducted by a doctor. During the teleoperation, the force data is recorded by constructing reaction force observer (RFOB) without utilizing force sensors. The recorded force data is then treated in the force modeling equation of needle insertion movements. Finally, the quantitative stiffness assessment method is presented. The proposed method is applied to the evaluation of stiffness of three different environments which all imitate the liver. The experimentally assessed stiffness values are compared with the stiffness measured by the durometer. The comparisons validate that the proposal is effective to quantitatively assess the stiffness of needle inserting environments.