Monday, March 16, 2015
CT SCAN OF HEAD
1.Interhemispheric fissure - Centered on the midline
2.Cortical sulcation Of cerebrum and cerebellum
3.Cerebral cortex width, Density (no calcifications or hemorrhages), No separation from the calvarium, No abnormal fluid collection (convex or concave) between the cerebral cortex and calvarium
4.Ventricles – Shape, Size, Symmetry (no unilateral or circumscribed enlargement), No signs of increased intracranial pressure (e.g. effaced sulci, narrowing or unilateral expansion of ventricles)
5.White matter Density (homogeneous, especially at periventricular sites)- No hypodensities (circumscribed, lacunar, or diffuse), No hyperdense changes (calcification, hemorrhage), Normal width in relation to cortex
6. Basal ganglia- Position, internal and external capsule, Delineation
7. Thalamus – Density
8. Brain stem – Shape, Density (homogeneous), No focal abnormalities
9. Cerebellum- General form (symmetry), Cortex (width, sulcation), White matter (homogeneous density)
10. Intracranial vessels- No abnormal dilatation, No vascular malformations
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- Contusions occur at the inferior and polar surfaces of the frontal and temporal lobes secondary to contact with bony surfaces during deceleration or due to depressed skull fractures.
- Produced by damage to parenchymal blood vessels leading to petechial haemorrhage and oedema.
- Contusions develop in surface grey matter tapering into white matter.
- Contusions are seen as multiple focal areas of low or mixed attenuation intermixed with tiny areas of increased density representing petechial haemorrhage.
- The CT appearance of fresh blood (acute hemorrhage) is that of a white (hyperdense) area in comparison to the grey colored brain.
- After a week, blood starts to appear grey like the brain or slightly darker than the brain. At this point, it is called a subacute hemorrhage (isodense or slightly hypodense).
- After several weeks, blood appears much darker than the grey brain, and it is then called a chronic hemorrhage (hypodense).
- Bleeding may occur in four areas within the skull, as intraparenchymal, subarachnoid, subdural or epidural hemorrhages
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INTRAVENTRICULAR HEMORRHAGE
RING ENHANCING LESION SUGGESTIVE OF BRAIN ABSCESS( IN THIS CASE ), METASTASIS AND GLIOMA
- Symmetry—Compare left and right sides of the cranium
- Midline—Look for midline shift
- Cross-sectional anatomy—Review anatomical landmarks for each slice
- Brain tissue—Gray matter, white matter, intracerebral lesions
- CSF spaces—Ventricles, basal cisterns, cortical sulci, and fissures
- Skull and soft tissues—Scalp swelling, fractures, sinuses, orbits
- Subdural windows—Look for blood collections adjacent to the skull
- Bone windows—Skull, orbits and sinuses, intracranial air
- Targeted Approach to CT Interpretation
- Trauma—Blood (extra-axial, intraparenchymal), cerebral edema, fractures, pneumocephalus, scalp swelling, coup, and contra-coup injuries
- Headache—Blood in the basilar cisterns (SAH), masses, hydrocephalus, cerebral venous sinuses thrombosis, paranasal sinusitis
- Stroke—Examine region of neurological deficit for blood, edema.
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