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

Abstract

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 (mVNav), 3) automatic registered (aVNav) or 4) CT-guidance. In case of ultrasonographically inconspicuous lesions, conventional US-guidance was abandoned and mVNav was used. If mVNav was also unsuccessful, the procedure was either continued with aVNav 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 mVNav, three (7.5 %) with aVNav and five (12.5 %) only through the use of CT-guidance. Of the three alternatives (mVNav, aVNav and CT only) the mean size of the lesions targeted using mVNav (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, mVNav allowed the ablation procedure to become less dependent on the use of CT. mVNav 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.

Value-assessment of computer-assisted navigation strategies during percutaneous needle placement

“…The registration of the ultrasound and PET-CT was based on aligning the position of the system’s “active tracker” as seen within the PET-CT with the tracker’s real-time location during the experiment. The active tracker contains metal fiducials that can be recognized in CT to acquire the position and orientation in the PET-CT. During the experiment, the real-time locations of the active tracker and US probe were identified using the individual EM tracking sensors [ 23 , 24 ]. Potential misregistration was corrected through correlating anatomical landmarks in both imaging modalities.…”

“…(1) The ultrasound system, (2) EM field generator, (3) phantom including imitation lesions, (4) EM active tracker and fiducial tracker, (5) biopsy needle with fiducials, (6) US probe including fiducials and (7) optical near infrared camera. b US display including navigational strategies and US probe were identified using the individual EM tracking sensors [23,24]. Potential misregistration was corrected through correlating anatomical landmarks in both imaging modalities.…”

Where Robotic Surgery Meets the Metaverse

“…The major Achilles’ heel for the implementation of these concepts during soft-tissue surgery is tissue movement. Patient positioning and respiratory motion alone can cause superimposition inaccuracies at the scale of centimeters [ 9 ]. CO 2 insufflation (commonly applied in abdominal robotic surgery) and surgical tissue manipulation inherently cause additional deformations that render any traditional landmark-based registration algorithm useless.…”