MRI-guided needle steering for targets in motion based on Fiber Bragg Grating sensors

The diagnosis and percutaneous treatment of prostate cancer require clinicians to accurately place needles into prostate tissue. However, the clinical targets often do not remain fixed while inserting the needles due to the displacement and deformation of the prostate. For magnetic resonance imaging (MRI) guidance, we developed a needle-steering method that enables reaching moving targets inside the prostate. A surgical needle with integrated Fiber Bragg Grating (FBG) sensors was designed to reconstruct the actual needle shape during insertion in the computer-assisted navigation system. The original needle-steering method for fixed targets is presented and its deficiency in reaching moving targets is discussed. Experimental results suggest that using the original method, one can accurately place the needle in the fixed targets, but the positioning error is considerably increased if the target is moved. In this study, we improved the original method to compensate for the inevitable tissue displacements. The experimental results show that with the developed method, the user can reduce the error in reaching the target. In particular, the improvement in the accuracy of needle steering operated by a novice user illustrates both the efficacy and user-friendliness of the proposed method.