Multimodal target correction by local bone registration: A PET/CT evaluation

PET/CT guidance for percutaneous interventions allows biopsy of suspicious metabolically active bone lesions even when no morphological correlation is delineable in the CT images. Clinical use of PET/CT guidance with conventional step-by-step technique is time consuming and complicated especially in cases in which the target lesion is not shown in the CT image. Our recently developed multimodal instrument guidance system (IGS) for PET/CT improved this situation. Nevertheless, bone biopsies even with IGS have a trade-off between precision and intervention duration which is proportional to patient and personnel exposure to radiation. As image acquisition and reconstruction of PET may take up to 10 minutes, preferably only one time consuming combined PET/CT acquisition should be needed during an intervention. In case of required additional control images in order to check for possible patient movements/deformations, or to verify the final needle position in the target, only fast CT acquisitions should be performed. However, for precise instrument guidance accounting for patient movement and/or deformation without having a control PET image, it is essential to be able to transfer the position of the target as identified in the original PET/CT to a changed situation as shown in the control CT. Therefore, we present a pipeline for faster target-position correction by isolating and registering the bone of interest, as shown in the control CT, with the CT dataset of the original PET/CT acquisition. Challenges such as the masking of the bone of interest and registration robustness in the presence of the needle and its associated metal artifacts are also addressed in this work. Our results confirmed the feasibility of clinically using this technique for target correction on PET/CT bone intervention, and motivated us to incorporate it as part of our IGS for multimodal intervention.