- Seen in older adults (55–75 years, male predominance) presenting subacutely with progressive headaches, cognitive decline, personality changes, new focal neurological deficits, or adult-onset seizures.
- Caused by WHO Grade 4 diffuse astrocytic glioma characterized by IDH-wildtype status, microvascular proliferation, and/or pseudopalisading necrosis; highly aggressive, infiltrative malignant neoplasm with dismal prognosis.
Imaging Findings
- Multiparametric Brain MRI (Diagnostic Standard):
- –Thick, Irregular, Nodular Peripheral Ring Enhancement: Markedly heterogeneous peripheral rim enhancement surrounding a non-enhancing, necrotic and cystic core.
- –Central Necrosis: Markedly hyperintense on T2WI and hypointense on T1WI, typically showing facilitated diffusion centrally (ADC high) due to liquefactive necrosis.
- –Restricted Diffusion in Solid Rim: Hypercellular peripheral viable tumor rim demonstrates hyperintensity on DWI and corresponding low ADC values.
- –Extensive Infiltrative Vasogenic Edema: Striking T2/FLAIR hyperintensity tracking along white matter tracts; tumor cells invariably infiltrate extensively into the non-enhancing FLAIR signal abnormality.
- –Cross-Midline Extension ('Butterfly Glioma'): Direct transcallosal infiltration through the genu or splenium of corpus callosum into contralateral hemisphere.
- –DWI / ADC: The thick, hypercellular enhancing peripheral rim shows diffusion restriction (high DWI, low ADC), whereas the central necrotic core shows facilitated diffusion (low DWI, high ADC)—the exact opposite of a pyogenic cerebral abscess.
- –**SWI / T2* GRE: Prominent irregular blooming artifact and intratumoral susceptibility signals (ITSS)** along the necrotic rim due to microvascular proliferation, neoangiogenesis, and intratumoral microhemorrhages.
- MR Perfusion & Spectroscopy (Physiological Signatures):
- –DSC Perfusion: Marked elevation of relative Cerebral Blood Volume (rCBV >2.5–3.0) in the enhancing rim and surrounding infiltrating edema (neoangiogenesis).
- –MR Spectroscopy (MRS): High Choline (Choline/Creatine ratio >2.0), profoundly depressed or absent NAA, and elevated lipid-lactate double peak at 1.33 ppm.
Differential Diagnosis
| Differential Diagnosis | Key Distinguishing Features |
|---|---|
Cerebral Abscess | Smooth, thin, uniform enhancing ring ('smooth inner margin'); non-enhancing dependent rim is hypointense on T2 (capsule); central liquefied pus demonstrates intense, uniform restricted diffusion (bright DWI, dark ADC); prominent surrounding edema. |
Solitary Brain Metastasis | Well-circumscribed, spherical enhancing lesion situated at the gray-white matter junction with disproportionate surrounding vasogenic edema; perfusion (rCBV) is elevated in the tumor rim but completely normal in the surrounding peritumoral edema (pure vasogenic edema, lacks infiltrative tumor cells). |
Tumefactive Demyelinating Lesion (TDL) | Open-ring or 'horseshoe' enhancement with the non-enhancing opening directed toward the cortical gray matter; less mass effect/edema relative to size; restricted diffusion along the leading advancing rim. |
Primary CNS Lymphoma (PCNSL) | In immunocompetent patients, densely homogeneous enhancing periventricular/subependymal mass with intense restricted diffusion (high cellularity, low ADC); lacks central necrosis; dramatic shrinkage following corticosteroids. |
Important Points to Remember
- Diagnostic Pitfall: Reporting peritumoral T2/FLAIR hyperintensity as 'pure vasogenic edema'! In glioblastoma, the surrounding FLAIR hyperintensity represents non-enhancing infiltrating tumor cells mixed with vasogenic edema. MR perfusion (DSC-rCBV) in this region shows elevated perfusion, distinguishing it from pure vasogenic edema surrounding brain metastases.
- Crucial Review Areas:
- 1.Corpus callosum (genu and splenium) for subtle transcallosal crossing ('butterfly glioma').
- 2.Subependymal ventricular lining for nodular enhancement (ventricular dissemination carries worse staging and precludes gross total resection).
- 3.Leptomeninges and distant brain parenchyma for multifocal or multicentric disease.
- 4.Internal carotid / middle cerebral artery branches for vascular encasement.
- Case-Specific Radiologist Management:
- 1.Immediate Verbal Alert: Direct telephone notification to on-call neurosurgical registrar for acute significant midline shift (>5 mm), impending subfalcine or transtentorial herniation, or acute hydrocephalus.
- 2.Avoid Pre-Biopsy Steroids if Lymphoma Mimic Suspected: If Primary CNS Lymphoma is in the differential, caution clinicians that high-dose Dexamethasone can cause rapid tumor lysis ('ghost tumor'), rendering diagnostic stereotactic biopsy non-diagnostic.
- 3.Functional Neuronavigation MRI Protocol: Perform volumetric 3D contrast-enhanced T1 (MPRAGE), DTI tractography (mapping corticospinal tracts and arcuate fasciculus), and functional MRI (fMRI for motor and language cortex) for neurosurgical navigation and maximal safe resection.
- 4.Spine Staging for Drop Metastases: If ventricular entry or ependymal enhancement is noted, perform urgent whole-spine MRI with contrast to screen for CSF drop metastases.
- 5.Neuro-Oncology MDT Presentation: Present to the Specialist Neuro-Oncology Multidisciplinary Team for planning maximal safe debulking surgery followed by Stupp Protocol (concomitant radiotherapy with Temozolomide [TMZ] chemotherapy) and molecular profiling (MGMT promoter methylation, IDH1/2 mutation status, and 1p/19q co-deletion).