Artikel
Characterization of malignant brain tumors through MR-quantification of the T1 relaxation times
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Autoren
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Stefan Motov
- Neurochirurgische Klinik und Poliklinik
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Christine Preibisch
- Abteilung für Neuroradiologie, Klinikum rechts der Isar, Technische Universität München
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Florian Ringel
- Neurochirurgische Klinik und Poliklinik
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Bernhard Meyer
- Neurochirurgische Klinik und Poliklinik
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Claus Zimmer
- Abteilung für Neuroradiologie, Klinikum rechts der Isar, Technische Universität München
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Annette Förschler
- Abteilung für Neuroradiologie, Klinikum rechts der Isar, Technische Universität München
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Jens Gempt
- Neurochirurgische Klinik und Poliklinik
| Veröffentlicht: | 2. Juni 2015 |
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Gliederung
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Objective: The differentiation between tumor tissue, edema, and diffuse infiltrated brain tissue is of importance regarding the treatment of patients with brain tumors. We attempted to differentiate and categorize the tumor entity and structural compounds as edema and necrotic tissue in patients with gliomas and cerebral metastases through measuring the quantitative T1 relaxation times.
Method: Pts with brain tumors underwent MR imaging for quantification of the T1 relaxation time of enhancing tumor tissue (T1T), of surrounding pathology (T1E – e.g. edema, non enhancing tumor or infiltration zone) and of normal appearing grey (T1GM) and white matter (T1WM). According to neuropathological examination, pts were subdivided into the subgroups metastasis (Met), glioma I°-III° (G1-G3), glioblastoma (G4) comparatively circumscribed tumors (TC), diffusely infiltrating tumors (TI). The group TC contains Met and G1, TI contains G2-4. For the T1 mapping a 3D FLASH-EPI Hybrid sequence was employed with two Flip angles of α1/α2 = 4.1º/23.6º, TE/TR 6.7/15.2 ms and isotropic resolution of 1 mm3. The total scan duration was 9 min 15 sec. To correct for spatial flip angle variations, B1 mapping was performed, taking additional 4 min 15 sec. Standard deviation and mean of the T1 relaxation time for each tumor group and each Volume of interest (VOI) was calculated.
Results: 36 pts were included. 25 pts suffered from gliomas (WHO I, n=3; WHO II, n=1, WHO III n=8, WHO IV n=13). T1E (edema) and T1T (contrast enhanced tumor) were significantly longer in infiltrative tumors (TI, n=22) than in brain metastases (Met, n=11) (p<0,05). G1 glioma revealed the longest T1T (mean 2713 ± 777 ms, max. 3262 ms). The lowest values were found in Met (mean 1450 ± 441, min. 692 ms). Again the shortest edema values T1E occurred in Met (mean 1635 ± 209 ms, mi. 1324 ms). T1WM (white matter) and T1GM (grey matter) displayed quite stable values among the groups without significant differences.
Conclusions: T1 mapping using a spoiled FLASH-EPI hybrid sequence with varying flip angles is an accurate method for differentiating between normal white (1104 ± 100 ms) and grey (1652 ± 80 ms) matter and tumor tissue with contrast enhancement (1810 ± 533 ms) or tumor edema (1825 ± 339 ms). There is a significant difference between the circumscribed tumors (T1T = 1957 ± 407 ms and T1E = 1947 ± 423 ms) and the diffusely infiltrating tumors (T1T = 1635 ± 209 ms and T1E = 1450 ± 441 ms) (p<0,05).
