Assessing the value of volume navigation during ultrasound-guided radiofrequency- and microwave-ablations of liver lesions.

Purpose: The goal of our study was to determine the influence of ultrasound (US)-coupled volume navigation on the use of computed tomography (CT) during minimally-invasive radiofrequency and microwave ablation procedures of liver lesions.

Method: Twenty-five patients with 40 liver lesions of different histological origin were retrospectively analysed. Lesions were ablated following standard protocol, using 1) conventional US-guidance, 2) manual registered volume navigation (VNav), 3) automatic registered (VNav) or 4) CT-guidance. In case of ultrasonographically inconspicuous lesions, conventional US-guidance was abandoned and VNav was used. If VNav was also unsuccessful, the procedure was either continued with VNav or CT-guidance. The number, size and location of the lesions targeted using the different approaches were documented.

Results: Of the 40 lesions, sixteen (40.0 %) could be targeted with conventional US-guidance only, sixteen (40.0 %) with VNav, three (7.5 %) with VNav and five (12.5 %) only through the use of CT-guidance. Of the three alternatives (VNav, VNav and CT only) the mean size of the lesions targeted using VNav (9.1 ± 4.6 mm) was significantly smaller from those targeted using US-guidance only (20.4 ± 9.4 mm; p < 0.001). The location of the lesions did not influence the selection of the modality used to guide the ablation.

Conclusions: In our cohort, VNav allowed the ablation procedure to become less dependent on the use of CT. VNav supported the ablation of lesions smaller than those that could be ablated with US only and doubled the application of minimally-invasive US-guided ablations.