Hyperdense Vessel Signs Showing Migration of a Thrombus

A 59-year-old man developed right hemiplegia and total aphasia. His National Institute of Health Stroke Scale score was 27. Serial multi-detector row non-contrast computed tomography (CT) with multiple planar reconstruction (MPR) revealed a hyperdense middle cerebral artery (MCA) sign in the left MCA (Picture A and B, arrow), and a diagnosis of acute ischemic stroke was made. Alteplase (0.6 mg/kg, IV) was started 165 minutes after onset. Repeat CT after completion of the alteplase administration revealed resolution of the hyperdense MCA sign but the appearance of an M2 dot sign (Picture C and D, arrowhead). Angiography showed the occlusion of the left MCA M2 segment, corresponding to the M2 dot sign (Picture E, arrowhead). The hyperdense vessel sign (HVS) is typically evaluated on axial CT images (1, 2). The present case demonstrated that serial multi-detector row non-contrast CT with MPR can not only recognize an HVS but also track a migrating thrombus. Early identification of the occlusion site can avoid unnecessary insertion of a large-bore sheath.