Acute Cerebral Artery Occlusion by a Calcified Embolus with False Patency Sign on Computed Tomographic Angiography

Computed tomographic angiography (CTA) is a quick and accurate method in triage to determine recanalization therapies for acute ischemic stroke. To minimize delay in the start of recanalization therapies, performance of CTA immediately after unenhanced brain computed tomography (CT) is recommended as the minimum standard. However, there are some pitfalls related to image interpretation of CTA in acute stroke, such as false patency sign. We describe the case of a 66-year-old man who presented with acute middle cerebral artery (MCA) occlusion by a calcified embolus with false patency sign on CTA after coronary angiography. We misinterpreted the CTA image as a patent MCA, and unnecessary brain magnetic resonance imaging caused delay in the start of endovascular thrombectomy. Our findings suggest that calcified cerebral emboli can present with false patency sign on CTA. To avoid misinterpretation of the CTA image and start recanalization therapy as soon as possible, physicians should be aware of false patency sign, especially when unenhanced CT shows hyperdense emboli and CTA findings do not correspond with patients' symptoms in acute ischemic stroke.