Vols. Videos


Last Updated: October 1, 2018

Classification of Head CT After Trauma
Grading system for brain injury based on cistern compression and midline shift
Diffuse Injury Grade CT Appearance Mortality
I Normal intracranial appearance 9.6%
II Basal cisterns present. Midline shift <5mm. No lesions. 13.5%
III Basal cisterns compressed or absent. Midline shift <5mm. No lesions >25cc. 34%
IV Midline shift >5mm. No lesions >25cc. 56.2%
Hounsfield Units Scale
Table with radiodensity measurements of important structures on CT scan
Basic Densities Hounsfield Units
Air at STP -1000 Hounsfield basic density
Water 0 Hounsfield basic density
Fat -60 to -120 Hounsfield basic density
Compact Bone +1000 Hounsfield basic density
Cranial Structures
Brain (Grey Matter) +30 to +40
Brain (White Matter) +20 to +35
Cerebral edema +10 to +14
CSF +5
Cranial Bone +600
Blood clot +75 to +80

Acute SDH, EDH, SAH;

Hct<23% → isodense to brain

Enhanced vessels+90 to +100
MRI Abbreviations
Abbreviation Description
T1WI Spin-lattice relaxation time – expresses realignment time of tissue’s proton spin
T2WI Spin-spin relaxation time – time constant for transverse magnetization decay...