BACKGROUND AND PURPOSE: Assessment of the collateral status has been emphasized for appropriate treatment decisions in patients with acute ischemic stroke. The purpose of this study was to introduce a multiphase MRA collateral imaging method (collateral map) derived from time-resolved dynamic contrast-enhanced MRA and to verify the value of the multiphase MRA collateral map in acute ischemic stroke by comparing it with the multiphase collateral imaging method (MRP collateral map) derived from dynamic susceptibility contrast-enhanced MR perfusion. MATERIALS AND METHODS:From a prospectively maintained registry of acute ischemic stroke, MR imaging data of patients with acute ischemic stroke caused by steno-occlusive lesions of the unilateral ICA and/or the M1 segment of the MCA were analyzed. We generated collateral maps using dynamic signals from dynamic contrast-enhanced MRA and DSC-MRP using a Matlab-based in-house program and graded the collateral scores of the multiphase MRA collateral map and the MRP collateral map independently. Interobserver reliabilities and intermethod agreement between both collateral maps for collateral grading were tested. RESULTS:Seventy-one paired multiphase MRA and MRP collateral maps from 67 patients were analyzed. The interobserver reliabilities for collateral grading using multiphase MRA or MRP collateral maps were excellent (weighted ϭ 0.964 and 0.956, respectively). The agreement between both collateral maps was also excellent (weighted ϭ 0.884; 95% confidence interval, 0.819 -0.949). CONCLUSIONS:We demonstrated that the dynamic signals of dynamic contrast-enhanced MRA could be used to generate multiphase collateral images and showed the possibility of the multiphase MRA collateral map as a useful collateral imaging method in acute ischemic stroke. ABBREVIATIONS:AIS ϭ acute ischemic stroke; DCE-MRA ϭ dynamic contrast-enhanced MRA; DSC-MRP ϭ dynamic susceptibility contrast-enhanced MR perfusion; mMRA ϭ multiphase MRA; MRP ϭ MR perfusion T he cerebral collaterals are alternative vascular channels for maintaining blood perfusion to the ischemic brain distal to an arterial occlusion. The collateral status varies among patients with Indicates open access to non-subscribers at www.ajnr.org http://dx.

Predicting the unseen arterial course and branching pattern distal to vessel occlusion is crucial for endovascular thrombectomy in acute stroke patients. We investigated whether a comprehensive interpretation of NCT and CTA would enhance arterial course prediction more than either NCT or CTA interpretation alone. Among 150 patients who achieved post-thrombectomy TICI grades ≥ IIb for anterior circulation occlusions, we assessed visualization grade on both NCT and CTA by five scales at the thrombosed and the distal-to-thrombus segment, using DSA as the reference standard. The visualization grades were compared and related to various subgroups. The mean visualization grade of the distal-to-thrombus segment on NCT was significantly larger than that of CTA (mean ± SD, 3.62 ± 0.87 versus 3.31 ± 1.20; p < 0.05). On CTA, visualization grade of distal-to-thrombus segment in the good collateral flow subgroup was higher than that in the poor collateral flow subgroup (mean ± SD, 4.01 ± 0.93 versus 2.56 ± 0.99; p < 0.001). After the comprehensive interpretation of NCT and CTA, seventeen cases (11%) showed visualization grade of distal-to-thrombus segment upgrading. Tracing arterial course and piecing branching patterns together in distal-to-occlusion of stroke patients was feasible on the routine pre-interventional NCT and CTA, which may provide timely guidance during thrombectomy.