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Congress: ECR25
Poster Number: C-11273
Type: Poster: EPOS Radiologist (educational)
DOI: 10.26044/ecr2025/C-11273
Authorblock: P. B. Hongal, M. Sheekey, H. Jaber, M. Wheeler; Cardiff/UK
Disclosures:
Prateek Basawaraj Hongal: Employee: NHS Wales
Margaret Sheekey: Employee: NHS Wales
Hisham Jaber: Consultant: NHS Wales
Matthew Wheeler: Consultant: NHS Wales
Keywords: CNS, Neuroradiology brain, CT, MR, Education, Neoplasia
Learning objectives Recognise hallmark MRI features of common posterior cranial fossa neoplasms on T1, T2, FLAIR, DWI, GRE/SWI, and post-contrast sequences. Differentiate benign from aggressive lesions posterior cranial fossa tumours. Be aware of any urgent complications such as hydrocephalus, brainstem compression, and haemorrhage caused by these masses.
Read more Background Posterior cranial fossa tumours are often linked to paediatric cases but remain a significant proportion of adult intracranial neoplasms, with high risk due to the confined space. The region contains critical structures (cerebellum, brainstem, ventricular system, vascular elements), making even small lesions potentially serious. Common tumours include ependymomas, haemangioblastomas, metastases, pilocytic astrocytomas, cavernomas, and epidermoid cysts, each with distinct MRI features. Overlapping imaging characteristics and mass effect complicate diagnosis, highlighting the need for specialised imaging techniques such as DWI, GRE/SWI, MR spectroscopy, and...
Read more Findings and procedure details Abbreviations T1 – T1-weighted MRI T2 – T2-weighted MRI FLAIR – Fluid-Attenuated Inversion Recovery DWI – Diffusion-Weighted Imaging GRE/SWI – Gradient Echo/Susceptibility-Weighted Imaging MRA/MRV – Magnetic Resonance Angiography/Venography CSF – Cerebrospinal fluid WBRT – Whole Brain Radiotherapy  1) Arachnoid CystOverview Benign, CSF-filled lesion between arachnoid layers. Can cause mass effect (cerebellar compression, hydrocephalus). No solid components or enhancement. Key Imaging Features T1: Isointense to CSF, no enhancement. T2: Hyperintense, follows CSF. FLAIR: Complete suppression. DWI: No restricted diffusion (differentiates from epidermoid). Post-contrast: No enhancement. Cine MRI: Assesses CSF flow, surgical relevance.  2) CavernomaOverview Vascular malformation with slow blood flow. Can be asymptomatic...
Read more Conclusion Overall, whilst there are some overlaps in radiological findings for posterior fossa tumours, we hopefully have provided some useful differentiating tips. It is pertinent to identify and differentiate these tumours whilst reporting, as they can cause compression of the brainstem and of the 4th ventricle, leading to hydrocephalus; whilst other lesions can remain more indolent and may not require biopsy nor intervention, reducing patient risk.
Read more References Osborn, A. G. Osborn’s Brain: Imaging, Pathology, and Anatomy (3rd ed.). Elsevier. [ISBN: 9780443109379]
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