Page 173 - Atlas of Small Animal CT and MRI

Brain Edema 163

Table 2.2.1 Distribution and causes of brain edema.
Cytotoxic Vasogenic Interstitial Osmotic
Distribution Intracellular gray and white Extracellular predominately Extracellular periventricular Extracellular
matter white matter
Cause Cell membrane Na/K pump Disruption of blood–brain barrier Increased intraventricular Systemic plasma
dysfunction due to cell resulting in extravasation of pressure. Usually from hypo‐osmolality
hypoxia from ischemia high‐protein fluid obstructive hydrocephalus

Figure 2.2.1 Cytotoxic Edema (Canine) MR

(a) T1, TP (b) FL, TP (c) T2, DP

3y FS Dachshund with right‐sided cerebellar infarction. There is a well‐circumscribed geographic region of FLAIR and T2 hyperintensity
involving the right cerebellum (b,c: arrow). The T2 hyperintensity is due, in part, to intracellular cytotoxic edema resulting from cell
hypoxia. The lesion distribution coincides with the tissue volume normally perfused by the right rostral cerebellar artery.

Figure 2.2.2 Vasogenic Edema (Canine) CT

3y MC Basset Hound with aspergillosis involving the frontal sinus and forebrain. This
unenhanced CT image is caudal to the primary lesion. Marked, diffuse hypoattenuation is
evident involving the white matter of the right cerebral hemisphere because of the presence
of vasogenic edema. Although edema is recognized on CT images, it may be less conspicuous
than on corresponding MR images.

(a) CT, TP

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