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40 Section I: Diagnostics and Planning
A
B C
Figure 4.13 Sagittal (A), dorsal (B), and T2‐weighted and transverse FLAIR (C) MRI of a dog with obstructive hydrocephalus due to a small mass (arrows
in A, B) compressing the mesencephalic aqueduct. Rostral to the mass there is severe dilation of the third ventricle. The FLAIR images show dilated,
rounded lateral ventricles and T2 hyperintensity in the periventricular region consistent with interstitial edema due to increased intraventricular pressure.
Table 4.1 T1 and T2 appearances of the five stages of parenchymal brain hemorrhage.
Phase Time (days) Hemoglobin Location T1 T2
Hyperacute <1 Oxyhemoglobin Intracellular Isointense or hyperintense Hyperintense
Acute 1–3 Deoxyhemoglobin Intracellular Hypointense Hypointense
Early subacute >3 Methemoglobin Intracellular Hyperintense Hypointense
Late subacute >7 Methemoglobin Extracellular Hyperintense Hyperintense
Chronic >14 Ferritin/hemosiderin Extracellular Hypointense Hypointense
