Acute Ischemic Stroke-Neuroradiological Update

抄録

Treatment decisions are increasingly based on neuroimaging not only for differential diagnosis of cerebral ischemia, parenchymal hemorrhage, cerebral venous thrombosis, acute encephalitis or brain edema but mainly due to its impact for the indication of different therapeutic options and impact for prognosis. The neurological score of deficits and the time window are most important factors for therapeutic regimen. However, since stroke is a highly complex and inhomogenous disease rigid orientation along these two parameters alone is not decisive for stroke therapy, but requires additionally specific imaging patterns either of MRI or CT. Further, findings in functional imaging point to the probability that the degree of hyperperfusion may play a more important role compared to the volume of an ischemic damage. Therefore prior to treatment neuroimaging should evaluate the location of arterial occlusion, the location and extension of parenchymal hypoperfusion and the penumbra as treatable and thus salvageable tissue at risk, which is regarded as the most relevant strokefactor.
To achieve all data mandatory for a conclusive stroke therapy, the so called "imaging triage", has to be performed within a maximum of 30 minutes including evaluation of the image. Though many imaging tools are available for stroke diagnosis such as USdoppler, SPECT, PET, CT, MR or DSA multimodality investigation is not recommended in respect to time pressure. The rationals and algorithms for diagnostic procedures depend on the sensitivity of methods for defining the target of reperfusion therapy avoiding reperfusion of damaged brain tissue. Moreover, the imaging techniques chosen must give early and correct information about the prognosis of clinical outcome and the prediction of malignant infarction. These prerequisites are best fulfilled at the moment by MRI, if all modalities (DWI, PWI, ce MRA) are used. However, the sensitivity of currently developing more sophisticated CT-techniques (multi-row perfusion CT, CTA source images, 3-D-CTA) approachs close to that of MR.
The implications of a modern imaging in stroke will be exemplified.