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（internal carotid artery occlusion, ICAO）与慢性颈内动脉闭塞患者具有重要临床意义，但目前仍缺乏易于应用且一致性可靠的鉴别方法。 目的：明确急性与慢性颈内动脉闭塞患者的磁共振灌注（MR perfusion）特征是否存在差异，并基于磁共振灌注结果提出一套鉴别诊断算法。 方法：本研究共纳入38例慢性颈内动脉闭塞患者与48例急性颈内动脉闭塞患者。对两组患者的灌注参数分别进行定量与定性比较，并基于定性评分构建决策树模型以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Tmax延迟病灶体积小于急性患者。以Tmax>10s的组织体积>2ml作为截断值时，鉴别慢性闭塞的敏感度最高（0.979，95%置信区间0.875~0.998），特异度亦为最优（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以对称型平均通过时间（mean transit time, MTT）异常（占比97.4%）及对称型脑血流量（cerebral blood flow, CBF）异常（占比94.7%）为典型表现；而急性颈内动脉闭塞患者则以Tmax延迟（100%）、MTT延长（97.9%）及CBF降低（81.2%）为特征。当采用基于上述灌注特征构建的决策树模型时，独立评估者可实现96.5%~98.8%的鉴别准确率，且评分者间信度极佳（一致性系数=0.89，95%置信区间0.82~0.97）。 结论：灌注成像在高精度鉴别急性与慢性颈内动脉闭塞方面展现出良好应用前景，本研究结果需在外部独立数据集内进行验证。