Stability of Thermoablation Antenna Using a Patient-Mounted Navigation System: Initial Clinical Experience

CT-guided microwave ablation (MWA) has become a standard procedure for a range of therapeutic and diagnostic indications, but accurate and stable positioning of the antenna is critical. In this retrospective case series, a navigation guide with a physical cube component, the Access Cube (AC), was investigated as a stability support in addition to its use as a navigation system. To our knowledge, this is the first investigation of stability in MWA.

Eight MWAs performed at one centre using the AC were reviewed for clinical and technical success. The stability of the antenna was assessed by subjectively comparing the Euclidian distance (ED) between the needle tip location in the final control scan and confirmation scan. A practising radiologist not associated with the study independently assessed the coordinates, and the mean was calculated from the results.

Six patients (eight procedures) were included (4 females). Mean age of the patients was 75.8 years (range 58-87). Diagnoses included liver metastasis (4, 50%), renal cell carcinoma (2, 25%) and 1 case each (12.5%) of hepatocellular carcinoma and lung metastasis. Mean tumour size was 2.4 cm (range 1.0-4.3 cm), with a mean depth of 10.6 cm (range 5-18 cm). Mean ED of needle tip between final control scan and confirmation scan was 5.82 mm. Technical and clinical success were achieved in all cases with one Grade 2 complication arising.

Usage of the AC was a beneficial addition to the MWA process. Good stability of the antenna was achieved when placed through the AC, eliminating the need for the clinician to manually hold the antenna in place during ablation.

Level 4, Case Series.