SEARCH

SEARCH BY CITATION

Keywords:

  • 5-amino-levulin acid (5-ALA);
  • fluorescence-guided resection (FGR);
  • glioblastoma multiforme;
  • optical touch pointer (OTP);
  • protoporphyrin IX (PpIX) fluorescence;
  • ultrasound navigation

Abstract

Background and Objective

Glioblastoma multiforme is a highly malignant primary brain tumor. It has no border but at best a marginal zone, however, invisible to the surgeon. An optical touch pointer (OTP) enabling differentiation of healthy and tumor tissue by means of fiber-optic fluorescence spectroscopy has been developed. In combination with an ultrasonic navigation system, the OTP may be used for demarcation of resectable tumor tissue. The aim of the study was to evaluate the clinical performance of OTP during surgery of malignant brain tumors.

Study Design/Materials and Methods

Nine patients were operated on with the standard surgical procedure, including white light microscopy and navigation. A total of 5 mg/kg bodyweight of 5-amino-levulin acid was orally administrated before surgery. The OTP was calibrated into the ultrasound-based navigation system and measurements were performed in tumor core and along the tumor border. The ratio between the protoporphyrin IX fluorescence at 635 nm and the autofluorescence was used for quantifications of data. Biopsies (n = 20), ultrasound images (n = 30), and visual inspection (n = 180) were compared to the fluorescence ratio.

Results/Conclusion

Healthy and tumor tissue could be identified and differentiated with the OTP (P < 0.001). The fluorescence ratio in average was 0 outside the tumor and low in the gliotic edema zone around the tumor. It increased in the marginal zone and was highest in the solid tumor tissue. In the necrotic tissue, in the center of the tumor, the ratio in average was 0. The OTP can be used in combination with ultrasound-based navigation and may help to determine whether to resect otherwise not identifiable tissue. Lasers Surg. Med. 43:8–14, 2011. © 2011 Wiley-Liss, Inc.