Percutaneous radiofrequency ablation of virtual tumours in canine kidney using Global Positioning System‐like technology

Abstract

What's known on the subject? And what does the study add? We have previously shown that percutaneous radiofrequency ablation guided by image-fusion technology allows for precise needle placement with real time ultrasound superimposed with pre-loaded imaging, removing the need for real-time CT or MR guidance. Emerging technology also allows real-time tracking of a treatment needle within an organ in a virtually created 3D format. To our knowledge, this is the first study utilising a sophisticated ultrasound-based navigation system that uses both image-fusion and real-time probe-tracking technologies for in-vivo renal ablative intervention. • To evaluate the feasibility, accuracy and efficacy of ultrasonography (US)-guided percutaneous radiofrequency ablation (RFA) in the canine kidney model using novel Global Positioning System-like probe tracking technology. • Virtual tumours in the canine kidney were ablated in vivo by percutaneous RFA guided exclusively by two-dimensional (2D) US and a virtual navigation system. • Gold fiducial markers were inserted into renal parenchyma to serve as centres of virtual tumours. • After capturing 2D US images, navigation software created a three-dimensional planning model of the kidney, and superimposed it onto the live US image. • Percutaneous RFA was guided by multiplanar navigation, showing real-time probe positions within the superimposed images, to treat each virtual tumour with a single treatment. • Navigator software predicted the percentage of tumour treated; treated kidney specimens were examined to evaluate projection and targeting accuracy. • In total, 32 virtual tumours (median diameter 16 mm, range 10-24 mm) were treated in 16 canine kidneys. • Median (range) error between 'fiducial tumour centre' and 'treated area centre' was 1.8 (0-25) mm. • Targeting accuracy improved with experience: median (range) error decreased from 6.3 (2-25) mm in an initial 12 tumours to 1.3 (0-9.0) mm in the last 20 tumours (P= 0.008). • The percentage (range) of tumour actually treated improved significantly from the initial series at 23% (0-100%) to 100% (51-100%) (P < 0.001). • Overall, navigator-reported and pathologically confirmed treatment percentages were correlated significantly (r= 0.5; P= 0.006). • Percutaneous renal RFA guided exclusively by real-time 2D US with multiplanar Global Positioning System-like probe tracking is feasible and accurate. • Near-future technologies, including elastic fusion overlay and anticipation of soft-tissue deformation, will further augment this guidance system.