Hemorrhage/contrast staining areas after mechanical intra-arterial thrombectomy in acute ischemic stroke: imaging findings and clinical significance.

BACKGROUND AND PURPOSE The aim of this study was to report the CT evolution and clinical significance of HCA after intra-arterial mechanical thrombectomy (revascularization by using retrievers and/or other mechanical devices without concomitant delivery of intra-arterial thrombolytics) in our patients. These lesions are common after intra-arterial thrombolysis, being considered a negative prognostic sign. Their significance after pure mechanical thrombectomy remains unknown. MATERIALS AND METHODS Forty-eight patients were treated with mechanical thrombectomy by using retrievable stents between April 2010 and February 2011. All patients underwent initial (first 24 hours) and follow-up (48-72 hours) nonenhanced CT. We retrospectively analyzed the clinical and radiologic data of the patients with HCA and compared them with controls. RESULTS Fifteen of 48 patients presented with HCA. The site of occlusion was the MCA in 7 patients, both the extra- and intracranial segments of the ICA in 6, and the intracranial ICA in 2. In 7 patients, previous intravenous thrombolysis was administered. Complete recanalization (TICI 3) was achieved in 12 patients, and incomplete recanalization (TICI 2b), in 3. The location of HCA was the subarachnoid space in 6 patients, the brain parenchyma in 4 patients, and both in 5 patients. The HCA were asymptomatic in all patients. There was no statistical difference in final NIHSS score reduction (NIHSS pretreatment-NIHSS at discharge) between patients and controls. CONCLUSIONS In our series, HCA are common after mechanical thrombectomy but do not carry an increased risk of symptomatic hemorrhage or negative prognosis. These data might be related to the high rate of recanalization and the absence of intra-arterial thrombolytics.