Acute Stroke Thrombectomy: Does CT Perfusion Accurately Predict Infarct on MRI After Recanalization

The newest generation of stent---retrievers results in higher recanalization rates and faster recanalization time compared to older generation endovascular therapies for acute stroke. Advanced neuroimaging can potentially improve the assessment of infarct core and inform decision---making in patients being considered for endovascular therapy. Evaluation of infarct core may be performed with NECT, CTASI or CT perfusion. In the past, evaluation of CTP in predicting core infarct in acute stroke has been limited because recanalization status was lacking. In addition, final infarct size may be underestimated on NECT compared with MRI. These two limitations can now be addressed: the new generation of stent---retrievers allows accurate determination recanalization time; evaluating the test characteristics of CTP using 24 hour DWI---MRI as the reference standard can be readily performed. We aim to prospectively investigate the sensitivity and specificity of whole---brain CTP in predicting 24 hour DWI---MRI infarct in patients with acute proximal anterior circulation occlusions successfully recanalized with endovascular treatment.

MRI screening will be performed as per standard-of-care by the MRI technologist staff. Imaging will be performed with 1.5 T or 3 T systems (Magnetom Vision; Siemens, Erlangen, Germany) using a multisection, single shot, spin echo, echo planer imaging sequence. Diffusion gradients will be applied in each of the x, y and z directions with three b values (0, 500 and 1000 s/mm2). Imaging parameters include a TE of 94 ms, field of view of 23 cm, matrix of 128 and section thickness of 5.5 mm for the 1.5 T system and a TE of 83 ms, field of view of 23 cm, matrix of 128 and section thickness of 3 mm for the 3 T system. Conventional spin echo imaging also will be performed at each examination under T1 and T2 weighted conditions, with a fluid attenuated inversion recovery sequence and Time-of-flight MRA of the Circle-of-Willis.

Evaluate the sensitivity and specificity of whole---brain CTP in predicting 24 hour DWI---MRI infarct in patients with acute proximal anterior circulation occlusions successfully recanalized with endovascular treatment.

The primary outcome of our study is to evaluate the sensitivity and specificity of CTP in predicting infarct on 24 hour DWI---MRI.

Inclusion Criteria: Admission NECT, CTA neck and COW or multi-phase CTA or CTP. Follow---up 24 hr DWI---MRI performed Endovascular therapy performed for acute anterior circulation stroke as per clinical practice. Patient with an angiographically documented ICA, M1 or M2 occlusion Exclusion Criteria: None