Imaging of Hematoma and Perihematomal Edema in Experimental Intracerebral Hemorrhage - Animal Models of Acute Neurological Injuries: Injury and Mechanistic Assessments - page 668

areas on each slice with the slice thickness and then subtracting the
hematoma volume from the hematoma plus edema volume. Up to
now there has been no clear consensus as to whether the hyperin-
tensity on FLAIR sequences refl ects edema caused by blood degra-
dation product-related brain damage or, at least in parts, acute
ischemic brain damage (i.e., due to compression of perilesional
arteries). Diffusion-weighted images (DWI) and calculation of
apparent diffusion coeffi cient (ADC) maps seem to be helpful for
differentiating between perihematomal ischemia and edema since
diffusion is reduced in acute ischemia with cytotoxic edema and
increased in vasogenic extracellular edema not related to ischemia ( 19 ).
Perfusion-weighted images (PWI) necessitating the injection of
gadolinium-DTPA for calculation of mean transit times may also
allow differentiation of ischemia from edema ( 19 ). It should be
noted that the diffusion and perfusion changes are quite subtle and
cannot be directly visualized. Therefore, measurement of quantita-
tive values in predefi ned regions of interest (ROI) is necessary to
detect these differences.

Only few groups have proposed imaging of the hematoma with
computerized tomography (CT). Shi and coworkers used CT scan-
ning in piglets ( 20 ). The comparatively small volume of the pig
brain in relation to the thick bone and the inability to visualize the
edema properly are the major restrictions of CT scanning.

3.2. Computerized
Tomography

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