[Cerebral perfusion CT: theoretical aspects, methodical implementation and clinical experience in the diagnosis of ischemic cerebral infarction].

Cerebral perfusion CT using dynamic CT after bolus injection of contrast has recently been introduced in the clinical management of stroke patients. Based on the indicator dilution principle various theoretical models can be formulated which all aim at the quantitative determination of cerebral blood flow (CBF). Our Perfusion CT approach is based on the "maximum slope" model and allows in addition to the calculation of CBF parameter images the display of cerebral blood volume (CBV) and "time to peak" as diagnostically meaningful parameters. This approach allows the detection of acute ischemia of the supratentorial brain with a sensitivity of 91% and has proven its value as a routine diagnostic tool for acute stroke. The combination of various functional maps provides excellent information regarding the type of ischemia. Although the direct assessment of ischemia using absolute CBF values is severely restricted by patient dependent systematic errors, the severity of ischemia may reliably be assessed by using relative CBF perfusion indices.