Intracranial hemorrhage (ICH) represents bleeding within the skull, either in the brain parenchyma or its coverings. CT is the first-line modality for acute cases, while MRI is useful in subacute/chronic stages and problem-solving.
📌 Types of Intracranial Hemorrhage & Imaging Features
1. Epidural Hematoma (EDH)
- Cause: Trauma, usually arterial (middle meningeal artery).
- CT:
- Biconvex/lens-shaped hyperdensity.
- Does not cross sutures but can cross dural attachments.
- MRI: T1/T2 variable; helps in subacute/chronic EDH.
- Clinical clue: Often with skull fracture; lucid interval.
2. Subdural Hematoma (SDH)
- Cause: Tearing of bridging veins.
- CT:
- Crescent-shaped, concave hyperdensity.
- Crosses sutures but not dural reflections (falx, tentorium).
- MRI: Sensitive for isodense or chronic SDH (T1 hyperintense if subacute).
- Clinical clue: Common in elderly, alcoholics, anticoagulation.
3. Subarachnoid Hemorrhage (SAH)
- Cause: Ruptured berry aneurysm, trauma.
- CT:
- Hyperdensity in basal cisterns, sulci, ventricles.
- MRI: FLAIR shows sulcal hyperintensity; SWI sensitive.
- CTA/MRA: Evaluate aneurysm/vascular malformation.
4. Intraparenchymal Hemorrhage (IPH)
- Cause: Hypertension, trauma, tumor, vascular malformations.
- CT:
- Well-defined hyperdense focus within parenchyma ± surrounding edema.
- MRI:
- Signal depends on hematoma age (oxyHb → deoxyHb → metHb → hemosiderin).
- SWI detects microbleeds.
5. Intraventricular Hemorrhage (IVH)
- Cause: Extension from SAH/ICH, trauma, vascular lesion.
- CT: Hyperdense layering in ventricles (“blood–CSF level”).
- MRI: T1/T2 signal changes, SWI sensitive.
- Clinical clue: Hydrocephalus common.
🕒 Aging of Hemorrhage on MRI (Quick Recap)
- Hyperacute (<24h): OxyHb → Iso T1, Hyper T2.
- Acute (1–3d): DeoxyHb → Iso T1, Hypo T2.
- Early Subacute (3–7d): Intracellular MetHb → Hyper T1, Hypo T2.
- Late Subacute (1–2w): Extracellular MetHb → Hyper T1 & T2.
- Chronic (>2w): Hemosiderin → Hypo T2 (rim).
🔎 Teaching Pearls
- EDH = convex, SDH = concave.
- SAH → think cisterns/sulci, best seen on CT within 24h.
- MRI SWI is highly sensitive for microhemorrhages & cavernomas.
- Always assess for underlying cause: trauma, aneurysm, AVM, tumor, coagulopathy.
