Adjunctive Flat-panel CT-based Reperfusion Grading after Endovascular Therapy: Enhanced Detection of Residual Distal Vessel Occlusion

BACKGROUND AND PURPOSE: The detection of residual distal vessel occlusion is crucial for the evolution of endovascular therapy outcomes. This study evaluated whether distal occlusion tracker signs on immediate postprocedural flat-panel CT could assist in the detection of residual distal vessel occlusion in patients with acute ischemic stroke due to large vessel occlusion after thrombectomy.

MATERIALS AND METHODS: A single-center retrospective analysis was conducted on patients with anterior circulation large-vessel occlusion who achieved successful reperfusion, defined as a modified TICI score of ≥2b, following endovascular therapy and underwent immediate postprocedural flat-panel CT and perfusion MRI. Two reviewers, blinded to the clinical data and perfusion findings, independently assessed the presence, number, and location of distal occlusion tracker signs on flat-panel CT and the final reperfusion state on cerebral DSA. Distal occlusion tracker signs were defined as dot-like, round, or tubular hyperdensities along the course of the distal intracranial arteries on immediate postprocedural flat-panel CT. Two datasets were compared: (I) using DSA alone, and (II) using DSA combined with flat-panel CT. A core laboratory determined the TICI grading and residual distal occlusion using both DSA and postprocedural perfusion MRI as reference standards.

RESULTS: The distal occlusion tracker sign was present in 65/156 patients (41.7%), with excellent inter-rater agreement (weighted kappa = 0.91; 95%CI, 0.85–0.96). Distal occlusion tracker signs demonstrated a sensitivity and specificity of 81.5 and 96.2%, respectively. The diagnostic accuracy in detecting residual distal occlusion was greater with the addition of flat-panel CT findings to DSA than with DSA alone (the area under the curve increased from 0.884 to 0.955, P=0.009). Reperfusion grading overestimation decreased from 17.9% with DSA alone to 3.8% with the addition of flat-panel CT to DSA.

CONCLUSIONS: Distal occlusion tracker signs are common findings on immediate postprocedural flat-panel CT, indicating residual distal vessel occlusion. The addition of flat-panel CT findings to DSA may enhance the detection of residual distal vessel occlusion after endovascular therapy.

ABBREVIATIONS: EVT = endovascular therapy; DVO = distal vessel occlusion; FPCT = flat-panel computed tomography; DOT = distal occlusion tracker; FPCT+DSA__TICI = TICI grading performed using FPCT and DSA; DSA__TICI = TICI grading performed using DSA alone; Core__TICI = TICI grading performed by the Core laboratory