Targeting accuracy of CT-guided stereotaxy for radiofrequency ablation of liver tumours

Abstract

The targeting accuracy during CT-guided stereotactic radiofrequency ablation (SRFA) of liver tumours was evaluated in a clinical study. Patients under general anaesthesia were immobilized using a vacuum cushion and respiratory motion control was based on temporary disconnections of the endotracheal tube. An optical-based navigation system was used for 3D trajectory planning and needle placement via a stereotactic aiming device. A control CT with the needles in place was fused with the planning CT for accuracy evaluation. Sub-analysis was performed for "location" (liver segments II-VIII), "approach" (intercostal or transabdominal), "properties" (clear parenchymal, subcapsular, subphrenic, fat, and subphrenic plus fat), and "path length". In 20 patients with 35 liver lesions, a total of 145 needles were placed with mean (±SD) lateral errors of 3.6 ± 2.5 mm at the needle tip, angular errors of 1.3° ± 1.2°, and longitudinal errors at the needle tip of -7.4 ± 6.2 mm. No puncture-related complications were noted. No significant differences of angular errors between segments, approach and properties were recorded. Long paths correlated with smaller angular errors. CT-guided stereotaxy can be considered safe and provided precise multiple needle placement for SRFA of liver lesions at arbitrary trajectories in various segments and locations.

Stereotactic image‐guided microwave ablation of hepatocellular carcinoma using a computer‐assisted navigation system

“…The geometrical accuracy of 3.2 mm median lateral error achieved with CAS‐One IR navigation system is comparable to similar navigation approaches in the literature. The group in Innsbruck reports lateral errors of 3.6 ± 2.5 mm in a series of 145 needle placements on 20 patients using an optical navigation system . Users of a robotic navigation system report applicator active point deviation after the first needle insertion of 5.3 ± 1.8 mm and 3.1 ± 2.5 mm for series of 21 resp.…”

Comparison of freehand-navigated and aiming device-navigated targeting of liver lesions

“…An automated registration method using single markers glued to the patient skin that are automatic and updated in real time was used in this study. In contrast, Widmann et al (12) used a manual registration to the planning dataset, using Beekley spots (Beekley Corp., Bristol, CT, USA) glued to the patient skin, a passive probe and a dynamic reference frame (DRF) attached to a patient-covering bridge on the intervention table. The Beekley spots (fiducials) visible in the CT dataset are defined on the navigation system, after which the spots on the patient are touched one after another by the passive probe.…”

Stereotactic Radiofrequency Ablation (SRFA) of Liver Lesions: Technique Effectiveness, Safety, and Interoperator Performance

“…The data were fused to the planning CT and allowed the actual needle position to be checked in relation to the planned path and target lesion [39].…”

“…The navigation probe was removed from the aiming device, and the adjustable breaks on the head were narrowed to guide the coaxial needle. One by one, each coaxial needle was advanced through the aiming device to the preplanned depth during short (10 s) temporary endotracheal tube disconnections [39]. A mean of 4.1 (median 3, range 1-14) coaxial needles per lesion were positioned.…”