Sonowand project: The safety and feasibility of intraoperative ultrasound to aid intrinsic tumour resection: a retrospective case-control series

Cameron Smail R, Brown A, Baldwin M, O’Neill KS

Standard neuronavigation using pre-operative imaging becomes increasingly inaccurate during tumour resection. Intraoperative imaging conveys a solution but to date MR systems can be time consuming and cumbersome. Intraoperativeultrasound (Sonowand™) provides real-time imaging and a 3D image volume to update the neuronavigationdataset but its disadvantages have yet to be analysed. We identified a cohort ofpatients with intrinsic tumours for which Sonowand™had been utilised. Primary end-points were 1) Impact on operation duration and 2) Post-operative complications

Retrospective case-control series

Eighty-two patients with intrinsic brain tumours resected using Sonowand™. Eighty-nine control patientsusing standard neuronavigation were identified.

Consecutive patients between Feb 2008 to April 2011 were identified as cases and controls. Controls matched for age, sex, tumour histology and tumour volume. Volume calculated on pre-op T2 weighted MRI scans assuming ellipsoid shape. Complications identified on manual searching of case notes and clinical correspondence. New neurological deficits labelled as major complications.

Groups were similar with regards median age (55 vs 57 years, p=0.89), gender (61% male vs 67% male, p=0.38), mean tumour volume (32cm3vs 30cm3, p=0.68) and histology.

No significant difference in total procedure time was observed. Median operation duration was 186 minutes with Sonowand™ and 140 minutes for controls (p=0.07). Number of major (6 vs 4) and minor (3 vs 5) complications were also similar. (p)

Intra-operative ultrasound has the potential to aid resection of intrinsic brain tumours. Although a relatively small sample our data suggest that there is no disadvantage with respect to operation duration or complication rates. Our preliminary data also suggests better volumetric resection with Sonowand™. Further data collection on resection volume and potential survival effect will be discussed