Testing objects are important for the validation of developing biopsy systems. Unfortunately, they are very hard to obtain. Motivated by this issue, the purpose of this study is to develop a technique for the easy creation of a model to simulate tumors of different sizes inside porcine livers, which could be used for ultrasound image-guided liver biopsy amongst other applications, and evaluate its performance by comparing to the more widely-used approaches in-vivo and ex-vivo. In this study, a Vaseline-based tumor model, and a more widely-used agar-based tumor model to provide comparison with the proposed method were created and injected into porcine livers as biopsy targets. The clinician located simulated tumors using real-time 2D imaging under the guidance of a robotic arm to delivery the biopsy in ex-vivo and in-vivo experiments. The results show that the optimum tumor model was created from a mixture of Vaseline, glycerol, and barium sulfate which can be easily produced and injected. All Vaseline-based simulated tumors were of solid, palpable mass on gross examination, and ultrasound imaging revealed clearly visible lesions. The clinician successfully performed ultrasound image guided liver biopsy in all the trials (10/10) in the ex-vivo experiment, and 2 out of 3 trials (2/3) in the in-vivo experiment on this optimum tumor model. We described a novel technique of creating solid liver tumor models that can be used for ultrasound image-guided liver biopsy.
Real-time MR temperature mapping of rabbit liver in vivo during thermal ablation