Introduction Thrombectomy has rates of successful recanalization of nearly 85%¹; however, many patients may not be eligible or not have a successful outcome following recanalization if the infarct evolves prior to arriving to the angiosuite. Neuroprotection that ‘freezes’ the penumbra to allow a longer window to receive treatment has become the next critical topic in stroke care². The canine temporary large vessel occlusion model has been recently developed to allow for assessment of neuroprotectants. A limitation of this model is the rate of stroke evolution tends towards one of two pathways: fast evolution, where more than half the total infarct volume is present within 90 minutes; and slow evolution, where less than half the final volume occurs within 90 minutes. Here we present a novel analysis of MR based Time-to-Peak (TTP) maps, derived from perfusion-weighted MRI (PW-MRI), to classify the canine stroke evolution based on the first PW-MRI.

Methods Fourteen dogs were retrospectively analyzed for patterns of stroke evolution. An autologous clot was injected into the MCA in order to cause an occlusion. Once the occlusion was confirmed, the animal was moved to the MRI scanner. MRI protocol included Time of Flight (ToF), Diffusion weighted (DWI) and perfusion weighted (PWI) imaging. For PWI 0.2mmol/kg gadopentetate dimeglumine was injected IV. To calculate the true volume of stroke, ADC maps were generated from the DWI images. The TTP maps were normalized relative to the unaffected contralateral half of the brain. The TTP map was registered to the DWI images to only account for voxels within the stroke volume. Finally, all voxels of the TTP map within the ADC lesion were binned into one of four categories: slight delay (4–8s), moderate delay (9–13s), long delay (14–18s) and extended delay (≥19s).

Results Using the DWI evolution as the ground truth, the canines were categorized into two groups of fast and slow evolvers (figure 1A). The binned TTP maps in the slight delay and extended delay groups also accurately predicted the evolution pathway in classifying all the canines in this study (figure 1B, p<0.01).

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Abstract O-027 Figure 1

A) ADC based stroke evolution, split into two groups, fast evolvers, and slow evolvers. B) TTP based classification of canines, predicting stroke evolution

Conclusions The ability to predict the rate of stoke evolution, at the point of first MRI, will allow for a better understanding of new therapeutics. Here we have shown that by analyzing the degree of delay from the TTP map, the rate of evolution of the stroke can be predicted.

References

1. Acute Stroke. Stroke 2017;48:1588–1593.

2. Stroke. 2011;42:3265-3270.

Disclosures R. King: None. O. Brooks: None. M. Gounis: None. M. Shazeeb: None.