Our study was part of the prospective multicenter Dutch acute stroke study (DUST), which was funded by the Netherlands Heart Foundation in collaboration with the MR CLEAN study, and received additional funding from the Nuts Ohra Foundation. The main aim of DUST was to investigate the use of advanced CT imaging (CTP and CTA) in outcome prediction in patients with acute ischemic stroke.¹

The treatment of ischemic stroke has changed greatly over the last 20 years, first with the emergence of thrombolysis (IV-rtPA) and, more recently, with the addition of intra-arterial thrombectomy (IAT).² Both treatments aim to resolve the obstructing clot. In a recent consensus meeting (Acute Stroke Imaging Research Roadmap II) it was suggested that revascularization is a combination of 3 mechanisms: recanalization (obtaining arterial patency at the location of the primary occlusion), reperfusion (antegrade microvascular perfusion), and collateralization (microvascular perfusion via pial arteries or other anastomotic channels that bypass the primary occlusion).³ All 3 parameters can be evaluated with advanced CT imaging. In many articles recanalization has been considered to be synonymous with reperfusion, but other articles suggest that reperfusion is a better predictor of final infarct volume and clinical outcome.⁴ In this study we evaluated the relationship between reperfusion and recanalization, and investigated which clinical and imaging parameters predict complete reperfusion in a population considered for treatment with IV-rtPA only.

We found that, although reperfusion is strongly related to recanalization, reperfusion and recanalization do not always occur in unison. Complete reperfusion can occur despite incomplete recanalization and incomplete reperfusion can occur despite complete recanalization. In a multivariable analysis investigating age, sex, NIHSS, IV-rtPA treatment, time to treatment, CBV derived infarct core, MTT derived total ischemic area, clot burden score, and collateral score, only the total ischemic area was an independent predictor of complete reperfusion.

The clinical implications of these findings are that the size of the area distributed by the occluded vessel is an important prognosticator of treatment success. The addition of an admission CTP to the stroke work-up could therefore provide a valuable tool to predict the treatment effect of IV-rtPA. In addition, follow-up CT with CTA to evaluate treatment success may give an inaccurate assessment of the revascularization in some cases, and routine CTP follow-up could be considered. Addition of CTP scan series should always take into account the age of the patient, as these will come with additional radiation exposure.

Some further studies from our group will focus on the relationship between clinical and imaging markers (including blood-brain barrier permeability) and the prediction of hemorrhagic transformation and space-occupying cerebral edema. These studies will be finalized later this year.

References

1. van Seeters T, Biessels GJ, Kappelle LJ, et al. The prognostic value of CT angiography and CT perfusion in acute ischemic stroke. Cerebrovasc Dis 2015;40:258–69, 10.1159/000441088
2. Berkhemer OA, Fransen PS, Beumer D, et al. A randomized trial of intraarterial treatment for acute ischemic stroke. New Engl J Med 2015;372:11–20, 10.1056/NEJMoa1411587
3. Wintermark M, Albers GW, Broderick JP, et al. Acute stroke imaging research roadmap II. Stroke 2013;44:2628–39, 10.1161/STROKEAHA.113.002015
4. Soares BP, Tong E, Hom J, et al. Reperfusion is a more accurate predictor of follow-up infarct volume than recanalization: a proof of concept using CT in acute ischemic stroke patients. Stroke 2010;41:e34–40, 10.1161/STROKEAHA.109.568766

 

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