Central nervous system disorders

I./3.2.: Computed tomography – CT

CT is well trusty imaging method to detect the hemorrhages. The acute bleeding – of any origion and localisation – appears hyperdense: 80-100 HU, in contrast to the brain parenchyma of 35 HU.

Destructive-space occupying feature is dominant in case of intraparenchymal mass hemorrhage, the hyperdense central area is sorrounded by a hypodense zone as sign of the perifocal edema. Several days later, a ring-like enhancement can develop around the hemorrhage following contrast administration due to damage of blood-brain barrier, which can be easily confounded by a hemorrhagic tumor. Later, the density of the hemorrhage decreases, and becomes isodense (flip-flop phenomenon), and finally hypodense. The residuum of the old, healed hemorrhages is liquordense, accordingly, „hole-like” appearence (lacunar), often stripe or track-like shape is seen with no more space occupying effect.

I./3.2.1.: History

Sir Godfrey Newbold Hounsfield (1919-2004) created the experimental model of computed tomography in 1971, which was introduced in the clinical routine in 1975. He was awarded by Nobel prize for this work in 1979. On the course of these innovates, Hounsfield created a radiodensity unit system, whose unit is the so called Hounsfield unit (HU). End values are the density of the destillated water on standard pressure and temperature – its value: 0 (zero) –, and the density of air in the same circumstances – its value: -1 000 (mínus thousand). HU-density values of several human tissue types – lung parenchyma: -500; fat: -84; cerebrospinal liquor: +15; spongious bone: +700; compact bone: + 3 000.