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Image-guided percutaneous ablation is the standard treatment for focal liver tumors deemed inoperable and is commonly
used to maintain eligibility for patients on transplant waitlists. Radiofrequency (RFA), microwave (MWA) and cryoablation
technologies are all delivered via one or a number of needle-shaped probes inserted directly into the tumor.
Planning is mostly based on contrast CT/MRI. While intra-procedural CT is commonly used to confirm the intended
probe placement, 2D ultrasound (US) remains the main, and in some centers the only imaging modality used for needle
guidance. Corresponding intraoperative 2D US with planning and other intra-procedural imaging modalities is essential
for accurate needle placement. However, identification of matching features of interest among these images is often
challenging given the limited field-of-view (FOV) and low quality of 2D US images. We have developed a passive
tracking arm with a motorized scan-head and software tools to improve guiding capabilities of conventional US by large
FOV 3D US scans that provides more anatomical landmarks that can facilitate registration of US with both planning and
intra-procedural images. The tracker arm is used to scan the whole liver with a high geometrical accuracy that facilitates
multi-modality landmark based image registration. Software tools are provided to assist with the segmentation of the
ablation probes and tumors, find the 2D view that best shows the probe(s) from a 3D US image, and to identify the
corresponding image from planning CT scans. In this paper, evaluation results from laboratory testing and a phase 1
clinical trial for planning and guiding RFA and MWA procedures using the developed system will be presented. Early
clinical results show a comparable performance to intra-procedural CT that suggests 3D US as a cost-effective
alternative with no side-effects in centers where CT is not available.
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