A biopsy tool for use in MR imaging for operation by a robot arm is formed of relatively brittle ceramic materials which have a magnetic susceptibility which is substantially equal to that of human tissue. The tool has slip couplings and bend joints designed to prevent overloading of forces on the sampling jaws. Cleaning ports are integrated into the design so that sterility can be obtained by flushing the device interior with a cleaning fluid. A novel spring-loaded capstan operated by a crank movable longitudinally of the tool ensures proper cable tension. A unique jaw shape enables a cutting pressure to be applied simultaneously around the desired tissue and does not depend on sharp edges to obtain the sample. Springs in the main casing provide cable tensioning to keep the jaws in a default closed position for movement of the biopsy device along a trajectory to the sample to be acquired.
