Glioma MRI

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor-In-Chief: Cafer Zorkun, M.D., Ph.D. [2], Sujit Routray, M.D. [3]

Overview

Brain MRI may be diagnostic of glioma.

MRI

Brain MRI may be diagnostic of glioma.

Type of glioma	CT findings
Pilocytic astrocytoma	1. T1: Iso- to hypointense solid component 2. T2: Hyperintense solid component
Low-grade astrocytoma	1. T1: Isointense to hypointense Confined to the white matter and causes expansion of the adjacent cortex 2. T2/FLAIR: Mass-like hyperintense signals Confined to the white matter and causes expansion of the adjacent cortex Cortex can also be involved in late cases in comparison to the oligodendroglioma, which is a cortical based tumor from the start Microcystic changes along the line of spread High T2 signal (not related to cellularity or cellular atypia, but rather edema, demyelination, and other degenerative changes) 3. DWI: No restricted diffusion Increased diffusibility 4. T1 C+ (Gd): No enhancement 5. MR spectroscopy: Tumor will show elevated choline peak, low NAA peak, elevated choline:creatine ratio Lack of the lactate peak 6. MR perfusion: No elevation of rCBV
Anaplastic astrocytoma	1. T1: Hypointense 2. T2: Hyperintense but can be heterogeneous, if calcification of blood present 3. T1 C+ (Gd): Variable enhancement Presence of ring enhancement suggests central necrosis 4. MR spectroscopy: Increased choline:creatine ratio NAA preserved or mildly depressed No significant lactate Intermediate levels of myo-inositol (lower than low grade, higher than glioblastoma) 5. MR perfusion: Elevated cerebral blood volume
Glioblastoma multiforme	1. T1: Hypo- to isointense mass within white matter Central heterogenous signal (necrosis, intratumoral hemorrhage) 2. T1 C+ (Gd): Variable enhancement Typically peripheral and irregular with nodular components Completely surrounds necrosis 3. T2/FLAIR: Hyperintense Surrounded by vasogenic edema Flow voids 4. GE/SWI: Susceptibility artifact on T2 from blood products or calcification Low intensity rim from blood product Located inside the peripheral enhancing component Absent dual rim sign 5. DWI/ADC: Solid component Elevated signal on DWI is common in solid / enhancing component Diffusion restriction is typically intermediate similar to normal white matter, but significantly elevated compared to surrounding vasogenic edema ADC values correlate with grade: WHO IV (GBM) = 745 ± 135 x 10-6 mm2/s WHO III (anaplastic) = 1067 ± 276 x 10-6 mm2/s WHO II (low grade) = 1273 ± 293 x 10-6 mm2/s ADC threshold value of 1185 x 10-6 mm2/s sensitivity (97.6%) and specificity (53.1%) in the discrimination of high-grade (WHO grade III & IV) and low-grade (WHO grade II) gliomas 6. Non-enhancing necrotic / cystic component: Vast majority (>90%) have facilitated diffusion (ADC values > 1000 x 10-6 mm2/s) 7. MR perfusion: rCBV elevated compared to lower grade tumors and normal brain 8. MR spectroscopy: Choline: increased Lactate: increased Lipids: increased NAA: decreased Myo-inositol: decreased
Oligodendroglioma	1. Hypodense to isodense 2. Calcification (70-90%) 3. Hemorrhage 4. Overlying skull may show pressure erosion
Ependymoma	1. Coarse calcification is common (50%) 2. Cystic areas (50%) 3. Iso- to hypodense solid component 4. Heterogeneous enhancement 5. Hemorrhage

Images shown below are courtesy of Professor Peter Anderson DVM PhD and published with permission © PEIR, University of Alabama at Birmingham, Department of Pathology

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References

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