Artikel
Diagnostic discrepancy between MRI-based non-GBM like tumours and molecular GBM-confirmation based on the 2021-WHO-classification of CNS tumours
Diagnostische Diskrepanzen zwischen MRT-basierten non-Glioblastom-Befunden und postoperativen molekularpathologischen Glioblastom-Nachweisen entsprechend der 2021-WHO-Klassifikation
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Veröffentlicht: | 25. Mai 2022 |
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Gliederung
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Objective: The aim of this study was to investigate the diagnostic specificity of magnetic resonance imaging (MRI) and MR spectroscopy (MRS) for grading of diffuse gliomas without typical glioblastoma (GBM) features against the new 2021-WHO-classification system of CNS tumors, which is mainly based on molecular-genetic characteristics.
Methods: All patients that presented between 01/2020 and 12/2021 with glioma suspicious tumors, that did not fulfill MRI criteria for GBM and underwent surgery or biopsy were assessed. The clinical setting as well as preoperative MR / MRS imaging were compared with the integrated histological and molecular diagnosis based on the 2021-WHO-classification, including EPIC-analysis. The following groups were defined: #1 LGG (MRI) – LGG (MRS) – GBM (pathology); #2 LGG (MRI) – grade 3 glioma (MRS) – GBM (pathology).
Results: Nineteen out of 61 gliomas (31.1%) were diagnosed as low grade gliomas (LGG) based on MRI data. All of these tumor patients underwent biopsy or surgery for definite histological and molecular-genetic diagnosis. 13 of these 19 LGG (MRI) (68.4%) specimen finally were diagnosed as GBM. Preoperative MRS, which was performed in all patients with glioma-like MRI-lesions, already revealed grade 3 glial tumors in three of those 13 tumors. Whenever MRS suggested a grade 3 tumor, pathological evaluation revealed a GBM.
Conclusion: This study proofed a discrepancy of 68.4% between an imaging based LGG diagnosis and final GBM diagnosis in accordance with the 2021-WHO-criteria. Therefore, in addition to preoperative MRI scans at least MRS with chemical shift imaging (CSI) should be added, especially for definition of the site of biopsy. Final integrated molecular-genetic pathological diagnosis then reveals the most precise classification and is essential for every further individualized therapeutic regime. In conclusion at least biopsy should be pursued of every glioma suspicious lesion.