Perfusion Profiles in Patients with Chronic and Acute Internal Carotid Artery Occlusion

Background It is important to identify patients with acute internal carotid artery occlusion (ICAO) from chronic ICAO, and there is still no easily applicable and consistent method for differentiation. Aims To determine whether the MR perfusion profile differs between acute and chronic ICAO, and to propose a diagnostic algorithm based on MR perfusion findings. Methods We included 38 chronic and 48 acute ICAO patients. Perfusion parameters were compared quantitatively and qualitatively between the two groups. Based on the qualitative ratings, a decision tree was built to differentiate acute from chronic ICAO. Results Chronic ICAO patients had smaller Tmax delay lesions than acute patients. A cutoff of >2ml of tissue with Tmax>10s had the highest sensitivity (0.979, 95% CI 0.875-0.998) and specificity (0.974, 95% CI=0.845-0.998) for identifying a chronic occlusion. The perfusion profile of chronic ICAO patients was characterized by symmetric mean transit time (MTT) (97.4%) and symmetric cerebral blood flow (CBF) (94.7%). While acute ICAO patients was characterized by Tmax delay (100%), prolonged MTT (97.9%), and decreased CBF (81.2%). When provided with a decision tree based on these profiles, independent raters could differentiate between acute and chronic ICAO with 96.5-98.8% accuracy and excellent inter-rater reliability (agreement coefficient=0.89, 95% CI 0.82-0.97). Conclusions Perfusion imaging shows promise for distinguishing acute from chronic ICAO with high accuracy. These results need to be validated in an external dataset.

背景 精准区分急性颈内动脉闭塞（acute internal carotid artery occlusion, ICAO）与慢性颈内动脉闭塞患者具有重要临床价值，但目前仍缺乏简便易用且标准统一的鉴别方法。
目的 明确急性与慢性颈内动脉闭塞患者的磁共振灌注成像（MR perfusion）特征是否存在差异，并基于磁共振灌注成像结果构建鉴别诊断算法。
方法 本研究共纳入38例慢性颈内动脉闭塞患者及48例急性颈内动脉闭塞患者，对两组患者的灌注参数分别开展定量与定性对比分析。基于定性评分结果构建决策树（decision tree），用于鉴别急性与慢性颈内动脉闭塞。
结果 慢性颈内动脉闭塞患者的达峰时间（Tmax）延迟病灶体积显著小于急性颈内动脉闭塞患者。以达峰时间>10s的脑组织体积>2mL作为鉴别慢性闭塞的截断值时，可获得最高的灵敏度（0.979，95%置信区间（confidence interval, CI）0.875~0.998）与特异度（0.974，95%置信区间0.845~0.998）。慢性颈内动脉闭塞患者的灌注特征表现为平均通过时间（mean transit time, MTT）对称（97.4%）与脑血流量（cerebral blood flow, CBF）对称（94.7%）；急性颈内动脉闭塞患者则表现为达峰时间延迟（100%）、平均通过时间延长（97.9%）与脑血流量降低（81.2%）。当独立评估者采用基于上述灌注特征构建的决策树进行鉴别时，诊断准确率可达96.5%~98.8%，且组间信度（inter-rater reliability）极佳（一致性系数（agreement coefficient）为0.89，95%置信区间0.82~0.97）。
结论 磁共振灌注成像在区分急性与慢性颈内动脉闭塞方面具有较高应用价值，诊断准确率优异。上述研究结果需在外部独立数据集中进一步验证。