CT perfusion imaging in acute ischemic stroke: comparison of perfusion maps and conventional CT findings.

To evaluate the findings of acute brain ischemia on different functional ma ps of cerebral perfusion CT in stroke patients and to compare the results w ith early ischemic changes on conventional CT. Methods: The baseline CT sca ns of 45 acute stroke patients were retrospectively evaluated with respect to early CT findings. For each patient the extent of cerebral ischemia as s hown on the maps of cerebral blood flow (CBF), cerebral blood volume (CBV), and "time to peak" (TP) was compared and the severity of ischemia was assi gned to one of three levels based on the findings of the CBF image. Results : In 75% of all patients conventional CT was performed within 2 hours from symptom onset. 29 of 45 patients showed early signs of ischemia on conventi onal CT, whereas perfusion CT revealed cerebral ischemia in all patients. S evere ischemia was found in approximately the same rate of incidence in pat ients with early CT changes (55.2%) and in those with normal findings (43.8 %). If the perfusion impairment was judged as mild or moderate the extent o f the hypoperfused area was significantly larger on the CBF and TP images t han on the CBV map. This was significantly different in patients with sever e hypoperfusion where a complete correspondence of the affected area betwee n the three functional maps was found. Discussion: The use of conventional CT for the assessment of stroke in the hyperacute phase is limited. Perfusi on CT yields excellent information regarding the severity and extent of isc hemia. The use of various perfusion maps helps to differentiate the core of infarction from the ischemic penumbra zone.