NeuroradiologyVasogenic oedema
oedema associated with brain tumours. When an oedema is associated with
infarction it is called cytotoxic (see
infarction cerebral). The mechanisms are different: cytotoxic oedema is related to arrested metabolism of the cells due to ischaemia with subsequent increase in
intracellular fluid; in tumours
vascular permeability is impaired so that plasma proteins and other macromolecules pass freely into the perivascular space and consequently into the
interstitial,
extracellular space. Vasogenic oedema may be noted also following
radiotherapy prior to necrosis.
The imaging pattern of vasogenic oedema involves mainly the white matter whose "digitations" become more evident. On CT increased hypodensity of the white matter is seen, while on MR decreased T1 and increased T2 signal in the same distribution is observed. The cortex is usually involved in cytotoxic oedema and spared in vasogenic oedema.
GS