Refining reperfusion assessment with flat-panel detector CT: association with final infarct volume after endovascular thrombectomy

INTRODUCTION: Distal occlusion tracker (DOT) signs on immediate post-interventional flat-panel detector CT (FDCT) can identify residual vessel occlusions underestimated by conventional angiography after endovascular thrombectomy (EVT). However, whether these FDCT-detected occlusions are associated with tissue-level outcomes remains unclear. We investigated whether FDCT-augmented reperfusion grading better reflects tissue imaging outcomes than operator-assessed reperfusion grading in patients with ischaemic stroke. PATIENTS AND METHODS: We retrospectively analysed EVT-treated patients with expanded thrombolysis in cerebral infarction (TICI) ≥ 2b who underwent post-interventional FDCT and follow-up MRI. DOT signs were defined as punctiform or tubular hyperdensities on FDCT. Final infarct volume (FIV) was segmented using follow-up DWI. Reperfusion status was categorised as incomplete (TICI 2b) or near-complete/complete (TICI 2c/3) based on FDCT-augmented TICI assessed by a core laboratory or operator-graded TICI. RESULTS: Among 200 patients, the median FIV was 20.0 mL (IQR, 5.9-74.6), and DOT signs were identified in 86 (43.0%). Operator-graded TICI classified 61 patients (30.5%) as having incomplete reperfusion, compared with 72 patients (36.0%) by FDCT-augmented TICI; 17 patients were reclassified. Compared with near-complete/complete reperfusion, incomplete reperfusion by FDCT-augmented TICI was associated with larger FIV (β = 24.0 mL; 95% CI, 3.6-44.4), whereas operator-defined incomplete reperfusion was not (β = 12.2 mL; 95% CI, -9.5 to 33.9). The model incorporating FDCT-augmented TICI explained slightly more variance in FIV than the model incorporating operator-graded TICI (adjusted R2 0.256 vs 0.239). CONCLUSION: FDCT-augmented reperfusion assessment may provide additional tissue-relevant information after EVT by identifying residual vessel occlusions associated with larger FIV.