RAPID Tmax map was useful for determining the site of acute right internal carotid artery occlusion presenting with cerebral infarction in the right posterior cerebral artery region

Abstract

Background: In computed tomography (CT) perfusion using rapid processing of perfusion and diffusion (RAPID), a relative cerebral blood flow (CBF) of 6 s is determined as the penumbra, and the perfusion mismatch is calculated. Here, we present the case of a patient with right posterior cerebral artery (PCA) occlusion based on RAPID analysis using CT perfusion. However, the Tmax map of RAPID revealed the acute occlusion of the right internal carotid artery (ICA) with fetal-type PCA.Case Report.A 94-year-old woman arrived at our hospital in an unconscious state and was admitted for emergency medical assistance. Magnetic resonance angiography revealed right PCA and right ICA occlusion, with blood supply to the right middle cerebral artery (MCA) showing cross-flow via the anterior communicating artery. RAPID analysis revealed a penumbra in the right PCA. Mechanical thrombectomy was performed for the right PCA occlusion via the basilar artery. During mechanical thrombectomy, the Tmax map of RAPID revealed acute right ICA occlusion with fetal-type PCA. On the Tmax map, the right MCA showed a Tmax of > 4 s, suggesting a blood flow disturbance in the right MCA. Mechanical thrombectomy for the right ICA occlusion via anterior circulation was performed, and TICI2b reperfusion was achieved. Conclusion: RAPID Tmax map was useful in the diagnosis of acute arterial occlusion. A penumbra may occur in cases with a Tmax of < 6 s.

Keywords

• RAPID
• Mechanical thrombectomy
• Tmax map
• Threshold
• Cross-flow