The invention concerns a preoperative probe (2) for guiding an ablation tool, comprising a sensing head (21), said sensing head including: at least one optic fiber (2121, 2123) for receiving and guiding a signal emitted, by radioactive tracers and/or fluorescent molecules in a tissue zone, to an analyzing equipment (32), fixing means (2112) for mounting the head (21) on the ablation tool (1), such that the ablation tool is capable of extracting a portion of tissue in the tissue zone emitting the signal.
