Accuracy and efficacy of percutaneous biopsy and ablation using robotic assistance under computed tomography guidance: a phantom study

Abstract

Objective: To compare the accuracy of a robotic interventional radiologist (IR) assistance platform with a standard freehand technique for computed-tomography (CT)-guided biopsy and simulated radiofrequency ablation (RFA).

Methods: The accuracy of freehand single-pass needle insertions into abdominal phantoms was compared with insertions facilitated with the use of a robotic assistance platform (n = 20 each). Post-procedural CTs were analysed for needle placement error. Percutaneous RFA was simulated by sequentially placing five 17-gauge needle introducers into 5-cm diameter masses (n = 5) embedded within an abdominal phantom. Simulated ablations were planned based on pre-procedural CT, before multi-probe placement was executed freehand. Multi-probe placement was then performed on the same 5-cm mass using the ablation planning software and robotic assistance. Post-procedural CTs were analysed to determine the percentage of untreated residual target.

Results: Mean needle tip-to-target errors were reduced with use of the IR assistance platform (both P < 0.0001). Reduced percentage residual tumour was observed with treatment planning (P = 0.02).

Conclusion: Improved needle accuracy and optimised probe geometry are observed during simulated CT-guided biopsy and percutaneous ablation with use of a robotic IR assistance platform. This technology may be useful for clinical CT-guided biopsy and RFA, when accuracy may have an impact on outcome.

Key points: • A recently developed robotic intervention radiology assistance platform facilitates CT-guided interventions. • Improved accuracy of complex needle insertions is achievable. • IR assistance platform use can improve target ablation coverage.

Figures

Fig. 1

Robotic interventional radiologist (IR) assistance platform set-up. a The robotic arm at baseline position (black arrowhead). Foot pedals (white star) can be used to initiate robotic arm movement and opening and closing of the end effector. Planning of percutaneous interventions are carried out and displayed on the monitor of the platform's computer console). b Robotic arm end effector grips onto the inserted needle guide before needle insertion

Fig. 2

Single-pass needle insertion planning using an IR assistance platform. Point target is delineated (white arrowhead) on axial images as well as reconstructed coronal and sagittal images (not pictured). Simulated needle trajectory is displayed as a dotted line on anatomical images

Fig. 3

Ablation planning on an IR assistance platform. Ablation planning software displays axial images (a) as well as reconstructed coronal and sagittal images (not pictured). After tumour segmentation (segmented tumour: white arrow, a), probes are planned and their trajectories displayed on the anatomical images (probes: solid/dotted lines in a). The predicted composite ablation zone is superimposed onto the segmented tumour on both multiplanar images and on a 3D shaded surface display (composite ablation zone: black arrow in a, white arrowheads in b)

Fig. 4

Analysis of ablation coverage. Representative image demonstrates residual target volume (black asterisks) and ablated volumes (white ovals) around inserted needles (white arrows)

Fig. 5

Scatter plots demonstrate the distribution of tip-to-target distance (a) for freehand and IR assistance platform-guided needle insertion. b Before-after plots demonstrate percentage residual tumour for each target using the freehand technique and the IR assistance platform