|Neurological History taking
| Causes of Stroke
The hemosiderin deposits that comprise microbleeds are superparamagnetic and have considerable internal magnetization when brought into the magnetic field of MRI
- Cerebral microbleeds are thought to have potentially important clinical implications in dementia and haemorrhagic stroke and in normal ageing.
- Small foci of chronic blood products in normal (or near-normal) brain tissue, designated here as cerebral microbleeds (CMB)
- Increasing recognitions since the development of MRI techniques tailored to detect magnetic susceptibility.
- Size definitions suggested for discriminating microbleeds from macrobleeds, typically ranging up to a maximum diameter of 5 to 10 mm and in some studies a minimum of 2 mm
- Normal ageing
- Dementia of Alzheimer's type
- Cerebral amyloid angiopathy: lesions in posterior cortical regions, particularly the occipital lobe
- Hypertensive stroke - lesions in basal ganglia, thalamus, brainstem, and cerebellum
- Calcium and iron deposits
- Flow voids in pial blood vessels seen in sulci
- Cavernous malformations and cavernous malformations
- Metastatic melanoma
- Dffuse axonal injury following head trauma
- Both T2*Gradient echo and SWI MR imaging sequences have a high sensitivity for microbleed detection
- It seems that sensitivity in detecting microbleeds was marginally higher on thick-/thin-section SWI compared with T2*.
- SWI is the sequence of choice in microbleed detection.
- Note that areas of low intensity that appear on T2*-weighted MRI are larger than the corresponding hemosiderin deposits, representing the so-called "blooming" effect.
- Presence of multiple microbleeds seems to suggest an increased risk of a cerebral haemorrhage.
- Their presence may be considered especially in terms of anticoagulation.
- Aetiology may be related to risks. CMB location may be important (deep hemispheric/infratentorial versus lobar only).
- Relationship to CAA and lacunar strokes and small vessels disease is yet to be untangled.
Comparing T2*and SWI
Clearly the right-handed image shows more detail of CAA and microbleeds