In breast cancer screening, suspicious lesions may be found that need to be checked for malignancy. A biopsy is the only diagnostic procedure for accurate histological confirmation, usually under ultrasound guidance. When sonographic placement is not allowed, a Magnetic Resonance Imaging-guided biopsy procedure is necessary.
The lack of real-time imaging information and the deformations of the breast make it difficult to bring the needle precisely towards the lesion detected in pre-interventional MR images: the current manual MRI-guided biopsy procedure is inaccurate and would benefit from a technique that allows real-time tracking and localisation of the lesion during needle insertion.
The main focus of the project is the development of a robotic setup and workflow to combine the high precision of MRI scanning with stereo vision localisation in the physical space to estimate the current target location and achieve an accurate needle placement and tissue extraction. In particular, the real-time tumour location is computed by optically tracking multimodality-visible markers attached on the skin of the patient. On MRI, the markers and the lesions which need to be biopted are precisely localized and then segmented in software. Subsequently, a tailored tracking system is exploited to evaluate the current position of fiducials and access surface deformations. Information acquired in the preoperative phase are combined with intraoperative data to compute and periodically update the current tumour location and plan the precise needle path for a robotically steered biopsy system. The last objective involved in this project is the control of a hand-mounted motorized needle angulation tool, which is able to carry out the biopsy procedure in the computed target location, taking into account deformations.
The workflow is validated through phantom experiments. On average, the breast suspicious lesion was targeted with a radius down to 2.3 mm. The results suggest that robotic systems taking into account breast deformations have potentials to tackle this clinical challenge.