Artikel
Dural infiltration of meningiomas analyzed with 5-ALA based fluorescence: operating microscope versus fiber optic probe – clinical pilot series
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Veröffentlicht: | 8. Juni 2016 |
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Objective: For meningiomas it remains controversial how much dura should be resected in order to achieve a "safe margin". So far, two methods to detect 5-ALA based fluorescence of meningeomas have been described: visual evaluation by the surgeon with a specially equipped operating microscope (Coluccia, 2010) and quantification of the fluorescence intensity with a fiber optic probe and a spectrometer (Valdes, 2014). In the present study we proposed to evaluate dural infiltration of meningiomas based on 5-ALA fluorescence either by an operating microscope or by quantitative measurements with a fiber optic probe and to correlate these findings with histopathological data.
Method: Nine patients operated for cranial or spinal meningioma with 5-ALA FGR were included (7 cerebral and 2 spinal). Dural tissue was analysed at multiple sample points. At these points fluorescence was assessed with a microscope (Zeiss OPMI Pentero Blue 400 (n=4) or Leica OH FL400 (n=5)) and recorded with a Brainlab Interactive Dicom Viewer BUZZ. Based on the recorded fluorescence signals it was rated as strongly positive (++), positive (+) or absent (-). After resection of small dura specimens at the defined sample points their fluorescence was immediately quantified ex vivo with a hand-held fiber optic probe connected to a spectrometer (Oceanoptics). Finally the dura specimens were histopathologically analysed for tumor.
Results: A total number of 64 dura specimens were analysed (average of 7.11 samples per tumor).The sensivity of the probe (87.5%) was significantly higher compared to the microscope (48.8%), p<0.01. Furthermore, the negative predictive value of the probe was significantly higher (82.1% vs. 52.3%, p< 0.01). The positive predictive value and specificity of both techniques were 100%.
Conclusions: In the presented setting, the probe was more sensitive in detecting tumor infiltration. The microscope showed increasingly false negative results following a centrifugal direction from the border of the tumor (“dural tail”). The main drawback of the probe was that it required a point-by-point acquisition and is not approved for clinical use in humans, nececessating ex vivo measurements. Whether such a method may have clinical impact remains to be shown.