Intraoperative ultrasound and 5-ALA: the two faces of the same medal?

High Grade Gliomas (HGG) still remain the most demanding neuro-oncological challenge. Several studies have confirmed that the extent of resection (EOR) correlates with increased survival in patients with HGGs. The Gross Total Resection (GTR) of HGGs can be difficult and challenging. For this reason, technologies to improve EOR have been of interest. The aim of this paper is to analyze advantages and limitations of both intra-operative fluorescence and intra-operative ultrasound (IOUS) resection techniques.

Our work deals with the comparison of one group of 15 patients treated with both tools (study group) with a control group of 15 patients in where only fluorescence was used. Post operative outcome are valued using Karnofsky Performance Status scale (KPS) while EOR are valued with MRI within 24 h after surgery.

The difference between the postoperative KPS and between EOR in the 2 groups resulted not statistically significant considering p<0.05. In our experience 5-ALA has a limited sensitivity before starting resection while shows it's central role in identifying the tumor remnants after its removal. Conversely, IOUS is very useful in identifying the tumor before starting resection. After the tumor removal, the sensitivity of the ultrasound in identifying tumor remnants in the margins of the cavity decreased significantly. However, in one case, at the end of resection, we have not visualized any fluorescent tissue but we detect a residual of tumor using the IOUS.

In our preliminary experience we observe that there are no significative advantages using IOUS plus 5-ALA. However we feel that IOUS is useful in first step of resection and fluorescence in the latest steps of operation. Therefore these two technologies could be considered the two faces of the same medal because they can help the surgeon to detect the tumor in all step of tumor removal.