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

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

Objectives:
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

Design:
Retrospective case-control series

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

Methods:
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.

Results:
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)

Conclusion:
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