Overview
MRI is preferred when available. CT is used when MRI cannot be performed, such as with certain implanted devices.
What imaging can show
- Strokes and small vessel disease
- Patterns of brain atrophy
- Tumors, bleeding, or fluid collections
- Normal pressure hydrocephalus
What imaging cannot show
- It cannot diagnose Alzheimer's disease by itself
- A normal scan does not rule out dementia
- Age-related findings are common and often not the explanation
Medically reviewed. Last reviewed August 2026. This page is educational information, not individualized medical advice.