Post radiation white matter injury. Metastatic disease to the calvarium.

Findings

Initial MRI of the brain shows numerous enhancing lesions scattered throughout the calvarium, consistent with metastatic bony involvement. There is also diffuse enhancement of the pachymeninges. There are no enhancing parenchymal lesions. Newer MRI of the brain shows confluent periventricular deep white matter FLAIR and T2 hyper intensities. There are no abnormal parenchymal lesions or enhancement. There is mild volume loss. There was no restricted diffusion (images not shown) to suggest infarct. Again seen are heterogeneous and enhancing calvarial lesions.

Differential diagnosis:
- Post radiation white matter disease
- Microvascular disease
- Age related white matter changes
- Tumor edema from metastatic or primary neoplasm
- Diffuse infectious process
- Diffuse inflammatory process


Diagnosis: Post radiation white matter injury. Metastatic disease to the calvarium.

Diagnosis is presumed based on this history: The patient has a history of widely metastatic breast cancer, with dural and calvarial involvement. The patient received chemotherapy and underwent whole brain radiotherapy. The white matter changes are nonspecific. However, given the history of radiotherapy, the abnormalities are likely sequelae of radiation treatment:


Key points - Radiation injury to the brain

Clinically:
- Many patients are asymptomatic
- Common complaints include confusion, personality changes, memory loss, and dementia
- Injury occurs in 38% to 50 % of patients after whole brain radiation
- Poor correlation of clinical symptoms with severity of imaging findings
- Amount of injury depends on dose and fractionation methods
- Latent period for appearance on injury on imaging is 6 to 8 months


Radiology

Changes of symmetric white matter injury
Periventricular white matter is particularly susceptible
Long term results is cerebral atrophy

CT:
- Confluent white matter hypo densities
- Usually no enhancement

MRI:
- More sensitive than CT
- T2 and FLAIR white matter prolongation
- Ranges from punctate periventricular foci to confluent changes extending from the ventricles to the corticomedullary junction
- May show ring enhancement if there is radionecrosis
- Usually no significant mass effect or enhancement