Table 6.
Identification characteristics of intracranial structures in CT head and TCS
| CT scan | TCS | |
|---|---|---|
| Sulcus | Hypodense | Hyperechoic (echogenicity higher than gyrus) |
| Gyrus | Isodense (density higher than sulcus) | Isoechoic (echogenicity lower than sulcus) |
| CSF (Ventricles or CSF-filled spaces) | Lowest density (HU ~ 0) | Anechoic |
| Acute hemorrhage | Hyperdense | Hyperechoic |
| Ischemic area | Hypodense | Hypoechoic |
| Perilesional edema | Hypodense | Hyperechoic |
| Old hemorrhagic lesions | Hypodense | Hypoechoic |
| Foreign body | Hyperdense/hypodense | Hyperechoic/hypoechoic |
| 1 Metal | High density (HU ~ 3000) | Hyperechoic (with posterior acoustic shadow or reverberation) |
| 2 Nonmetal | Hyperdense/hypodense (depends on the content) | Hyperechoic/hypoechoic (depends on the content) |
| EVD | Linear/round hyperdensity in lateral ventricle | Linear/round hyper-echogenicity with or without reverberation |
| Lateral ventricle (axial section) | Elongated curve-like shape [hypodense (CSF)] | Elongated curve-like shape (anechoic content) |
| 3rd ventricle (axial section) | Small round with hypodense (CSF) content | Small round with anechoic content |
| 4th ventricle (axial section) | Semilunar-shaped hypodense (CSF) | Semilunar-shaped (anechoic content) |
| Possible sections | Axial/coronal/sagittal | Axial/coronal/sagittal (depends on post-craniectomy site) |
| Imaging | Static | Dynamic |