[Value of modern CT-techniques in the diagnosis of acute stroke]

Abstract

Background: Thrombolysis is the treatment of choice for acute stroke within 3 h after symptom onset. Treatment beyond the 3 h time window has not been shown to be effective in any single trial, however, metaanalyses suggest a somewhat less but still significant effect within 3 to 6 h after stroke. It seems reasonable to apply improved selection criteria that allow to differentiate the patients with a relevant indication for thrombolytic therapy from those who have not. While stroke MRI seems to be the upcoming standard, due to its low availability the need for an improved CT-based patient selection is evident.

Methods: The present literature on imaging in stroke has been thoroughly reviewed. The diagnostic strengths and weaknesses of conventional CT, CT angiography (CTA), CTA source image analysis (CTA-SI) and perfusion CT (PCT) for an acute diagnostic stroke workup are critically reviewed in this article. The authors present their view about a comprehensive diagnostic approach to acute stroke in accordance to stroke MRI findings, which allows to challenge the rigid therapeutic time window and improve patient management.

Conclusion: Information about the presence or absence of ICH by non contrast CT and vessel occlusion by means of CTA is deemed obligatory before rt-PA is given in the 3-6 hour time window. Clear demarcation of an early hypodensity exceeding 1/3 of the MCA territory on NCCT or CTA-SI should preclude thrombolytic therapy. The irreversibly damaged infarct core and the ischemic but still viable thus salvageable tissue at risk of infarction as seen on CT/CTA/CTA-SI/PCT should be obtained before thrombolysis is initiated within 3-6 hours. Once these advanced techniques are used, the therapeutic time window can be extended with acceptable safety. However, comprehensive informed consent is mandatory, especially when thrombolytic therapy is considered beyond established time windows.