Wednesday, February 15, 2012

Spontaneous Intracerebral Hemorrhage (Volume Determination by CT)

Figure 1. CT depicts a large intracerebral hemorrhage on the left. The calipers show how to measure the size of the blood clot.

Figure 2. Number of slices on which the hemorrhage is seen. Thickness 1 cm and interval of 1 cm (4 images = 4 cm in this example).

Spontaneous intracerebral hemorrhage (SICH) is a hematoma that arises in the brain parenchyma in the absence of trauma or surgery. This entity accounts for 10% to 15% of all strokes and is associated with a higher mortality rate than either ischemic stroke or subarachnoid hemorrhage.

Common causes include hypertension, amyloid angiopathy, coagulopathy, vascular anomalies, tumors, and various drugs. Hypertension, however, remains the single greatest modifiable risk factor for SICH.

Many modern CT scanners are able to calculate hematoma volume directly by using special software. If direct volume measurements are not possible, a rapid, simplified method of determining hematoma volume has been described and validated.

The "abc method" uses the formula (a x b x c)/2, in which a is the largest diameter (in cm) of the hematoma in the CT slice with the largest area of ICH, b is the largest diameter (in cm) of the hemorrhage perpendicular to line a; and c is number of slices with hematoma multiplied by the slice thickness in cm. This formula yields hematoma volume in cm3 (cc).

4.65 x 2.51 x 4/2 = 23.3 cc in this case.


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