ABSTRACT
Clinical studies have revealed high selectivity of 5-ALA-induced protoporphyrin IX accumulation in different brain tumors. Modern methods of evaluation of tissues visible fluorescence are based on the qualitative analysis of the images. Up-to-date methods of combined spectral analysis allow fulfilling the intraoperative quantitative evaluation of the protoporphyrin IX content, as well as the scattering and absorption properties of a tissue. This paper presents a new method of the simultaneous analysis of hemoglobin concentration in oxygenated and reduced forms, tumor marker concentration (5-ALA-induced PP IX) and a new way to analyze the changes in the scattering properties of the tissues. The method is implemented by splitting the visible spectrum into intervals where hemoglobin and protoporphyrin IX have the characteristic peaks of absorption and fluorescence. The present method shows the dependence of the fluorescence index from the tumor grade. Combined spectroscopy (optical biopsy) can detect the differences between the subtypes of gliomas that are similar in the protoporphyrin IX fluorescence index. This method complements and enhances the diagnostic capabilities of spectroscopy, which is particularly important in the non-fluorescent glioma surgery.
ABSTRACT
Photodynamic diagnosis (PDD) has been actively implemented into neurooncological practice, especially in cerebral gliomas surgery. This paper describes our first experience of PDD combined with laser spectroanalysis in intracranial meningiomas. The study included 21 patients (8 male and 13 female patients, mean age was 58 years, range--between 37 and 74 years) with intracranial meningiomas operated with PDD in Burdenko Neurosurgical Institute between 2008 and 2011. In 14 cases laser spectroanalysis was used. Tumor fluorescence was present in all but one cases (95%). Spectroanalysis demonstrated that peaks of fluorescence varied between 5 and 46 (mean level was 18.5). These data correlated with visual impression of fluorescence and confirmed that meningioma is a tumor with bright fluorescence. Radical removal (Simpson grade I-II) was achieved in 10 cases, subtotal resection was performed in the rest of the patients. Application of PDD and laser spectroanalysis allows gaining complete information about accumulation of photosensibilizer in the tissue. To our opinion, these methods may be the most useful for determination of the borders of dural and bony invasion which directly affects the surgical tactics and degree of radical removal. Further studies are needed to evaluate the influence of PDD and laser spectroanalysis on long-term surgical outcomes.
Subject(s)
Meningeal Neoplasms/diagnosis , Meningioma/diagnosis , Adult , Aged , Diagnosis, Differential , Female , Fluorescence , Humans , Lasers , Male , Meningeal Neoplasms/surgery , Meningioma/surgery , Middle Aged , Spectrum AnalysisABSTRACT
Absence of well-defined borders of the glial tumor due to their infiltrative growth is one of the main issues in neurosurgery. A number of methods for intraoperative visualization are available today. The fluorescent metabolic navigation with 5-aminolevulinic acid (5-ALA) combined with quantitative laser spectroscopy is one of the latest technique. In our series of 99 consecutive patients with brain gliomas (WHO Grade I-IV) we found that visible fluorescence was observed in 68% of cases. Additional use of the laser spectroscopy could increase method sensitivity up to 74% due to accumulation of the protoporphyrine IX in nonfluorescense tumors. It was shown that there are some differences in quantitative fluorescence not only within same tumor (glioblastoma) but also in-between low- and high-grade gliomas. Intraoperative fluorescence and laser spectroscopy are effective and very helpful methods of intraoperative imaging in of intrinsic brain tumor surgery.