False patency, true occlusion: perfusion imaging and dual stent-retriever thrombectomy for a calcified carotid terminus embolus

Calcified cerebral emboli are an uncommon cause of acute ischemic stroke and may produce a false-patency sign on computed tomography angiography because their high attenuation can mimic intravascular contrast material. We report the case of a 77-year-old woman who presented with a wake-up stroke approximately 14 hours after she was last known well, with right hemiplegia and global aphasia. Noncontrast computed tomography showed a markedly hyperattenuating intraluminal focus at the left carotid terminus and proximal M1 segment, suggesting a calcified cerebral embolus. Computed tomography angiography appeared to show severe stenosis with residual luminal patency, whereas computed tomography perfusion demonstrated extensive hypoperfusion involving the left middle cerebral artery and bilateral anterior cerebral artery territories. Because the severe neurologic deficit and perfusion abnormality were discordant with the apparent patency on computed tomography angiography, cerebral angiography was performed. Digital subtraction angiography demonstrated complete occlusion of the left M1 origin and near-complete occlusion of the left A1 segment; the right A1 segment was congenitally hypoplastic. A rigid calcified embolus spanning the carotid-terminus bifurcation was retrieved using a balloon guide catheter-assisted dual-stent technique under proximal flow arrest, achieving complete reperfusion in a single pass. Histopathologic examination confirmed calcified embolic material. This case highlights the value of multimodal imaging and confirmatory angiography when clinical and imaging findings are discordant. In this patient, balloon guide catheter-assisted dual-stent retrieval was a tailored and feasible strategy; however, a single case cannot establish its superiority over other thrombectomy approaches.