Artikel
Fibre density mapping and 18F-fluoroethyl-tyrosine PET for classification of white matter fibre tract alterations in the vicinity of gliomas
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Veröffentlicht: | 28. April 2011 |
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Gliederung
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Objective: Diffuse tumor infiltration pose a problem in therapy planning. Fibre density mapping (FDM) is a new approach for post-processing of diffusion tensor imaging (DTI) data. FET-PET is a specific tumor imaging modality. We used FDM and FET-PET for classification of WM fibre tract alterations in the vicinity of gliomas.
Methods: Routine MRI, DTI and FET-PET were performed in 26 patients with gliomas WHO II-IV. FD values were calculated from DTI data and co-registered to PET data using mutual information. FDM data were used to segment fibre structures in the vicinity of the lesions and in contralateral WM. FD and FET values were evaluated as tumor-to-brain ratios. Based on the results of Pauleit et al. (Brain 2005) we defined four different categories of FET-uptake: tumor infiltration (FET > 1.6); gliosis, microglial activation, or/and oedema (FET > 1.1), normal brain (FET > 0.9) and decreased uptake (FET < 0.9). FD ratio-values (FDR) were grouped in increased (> 1.1), normal (0.9 > FDR < 1.1) and decreased (< 0.9).
Results: Based on the four FET categories in combination with the three groups of FD values we defined ten potential patterns of fibre tract alterations in the vicinity of gliomas. FET > 1.6 and FDR > 1.1: tumor infiltrated, compressed but intact fibres (this pattern showed one pt); FET > 1.6 and normal FD: slight tumor infiltrated, only translocated but intact fibres (2 pts) or tumor infiltrated, compressed and partly destroyed fibres (4 pts); FET > 1.6 and FDR < 0.9: tumor infiltrated, not (anymore) compressed and partly destroyed fibres (6 pts). FET > 1.1 and FDR > 1.1: gliotic/oedematous, compressed and intact fibres (7 pts); FET > 1.1 and normal FD: gliotic/oedematous, only translocated and intact fibres (4 pts); FET > 1.1 and FDR < 0.9: gliotic/oedematous and widened/partly destroyed fibres (16 pts); FET > 0.9 and FDR > 1.1: compressed and intact fibres (12 pts); FET > 0.9 and normal FD: only translocated and intact fibres (7 pts); FET > 0.9 and FDR < 0.9: widened or partly destroyed fibres (9 pts); FET < 0.9 and FDR < 0.9: strongly oedematous and partly destroyed fibres (1 pt). All patients showed more than one pattern.
Conclusions: We presented a multimodal imaging strategy for classification of WM fibre tract alterations in the vicinity of gliomas. We demonstrated that WM changes in the border zone are more complex as described in literature. This may be helpful to prevent post-therapeutic neurologic deficits.