Radio-guided neurosurgery (RGNS): early experience with its use in brain tumour surgery

Abstract

Definition: Radio Guided Neurosurgery¹ (RGNS) is a technique using systemic administration of radionuclide in which a gamma probe is used intra-operatively to identify isotope-rich brain tumour, and check for residual lesions after excision of visually identifiable lesion.

Aims: To assess the usefulness of this technique in surface-localizing brain tumours, in real time, intra-operative identification of tumour from brain, and in assessing completeness of excision. Tumours in or near eloquent areas are of special interest.

Settings and Design: Prospective, non-randomized and non-blinded.

Methods and Material: The study included 19 patients with intrinsic brain tumours operated between July 2005 & December 2006. A high degree of radioisotope uptake was confirmed on Single Positron Emission Computed Tomography (SPECT) with fusion of Computed Tomographic (CT) images (SPECT-CT) in all patients after IV injections of 99m Technetium Sestamibi (Tc). We use a Euro 4 Probe (Euro Medical Instruments, Paris) which detects gamma emissions. Intra-operatively, the probe was used to identify tumour from normal brain using a difference in activity of a factor of 2. The end point was complete tumour removal as determined by absence of significant residual activity.

Results and Conclusions: This inexpensive and highly portable system provides realtime, intra-operative identification of tumour and assessment of completeness of tumour excision. It can guide the location of craniotomy and identify visually indistinct tumor from normal brain, a situation where the surgeon may leave behind residual tumour to avoid serious deficits. The use of RGNS enhances the neurosurgeon's confidence with tumours in or near eloquent areas and provides reliable proof of the completeness of excision in real time.

Key words:

• Brain tumour
• intraoperative guidance
• Technetium 99
• SPECT