Supplementary Material for: Multi-Contrast High-Resolution Magnetic Resonance Findings of Spontaneous and Unruptured Intracranial Vertebral Artery Dissection: Qualitative and Quantitative Analysis According to Stages

<b><i>Background:</i></b> Although high-resolution magnetic resonance imaging (HR-MRI) has been used as a strong imaging method for diagnosing intracranial vertebral artery dissection (IVAD), the diagnosis is sometimes challenging because a dissection has geometric changes in the natural course. The radiologic features may change or disappear over time, which makes the diagnosis confusing. Our study was to present radiological findings according to the stages in spontaneous and unruptured, IVAD on 3T HR-MRI and to guide the age estimation of IVAD with the distinguishing findings according to the stages. <b><i>Methods:</i></b> From January 2011 to July 2014, the 41 vertebral arteries (M:F = 18:12; age range 32-67 years) were retrospectively enrolled. Spontaneous, unruptured IVAD was diagnosed if it had a clear onset based on clinical and radiological findings. The stages were classified as acute (0-3 days), early subacute (3-10 days), late subacute (10-60 days) and chronic stage (&gt;60 days; recovery and non-recovery groups) according to the time intervals from symptom onset, based on the prior published studies. HR-MR findings were assessed and compared in the intimal flap, double lumen, aneurysmal dilatation (maximal outer diameter, maximal wall thickness, wall thickness index and remodeling index), intramural hematoma (relative signal intensity) and vessel wall enhancement according to the stages with qualitative and quantitative methods. Two radiologists analyzed the HR-MR findings with consensus reading. <b><i>Results:</i></b> IVAD was classified into acute (n = 6), early subacute (n = 8), late subacute (n = 16) and chronic (n = 11) stages. HR-MR dissection findings such as intimal flap, double lumen, aneurysmal dilatation and intramural hematoma significantly decreased from the earlier stages to the chronic stage (p &lt; 0.05). The quantitative indices in aneurysmal dilatation and the relative signal intensity of intramural hematoma showed significant higher values in the earlier stages followed by a significant decrease in the chronic stage recovery group (p &lt; 0.05). The degree of vessel wall enhancement was higher in the earlier stage and decreased in the chronic stage (p &lt; 0.05), but mild vessel wall enhancement was identified 900 days after symptom onset. <b><i>Conclusion:</i></b> The 3T HR-MRI reveals the vessel wall characteristics and provides distinguishing findings between earlier stages and the chronic stage in spontaneous and unruptured IVAD. Characterization of these radiological findings according to stages may assist with the age estimation of the dissection and may help to understand IVAD as a whole.

<b><i>背景:</i></b> 尽管高分辨率磁共振成像（high-resolution magnetic resonance imaging, HR-MRI）已作为诊断颅内椎动脉夹层（intracranial vertebral artery dissection, IVAD）的可靠影像学手段，但由于夹层在自然病程中存在几何形态改变，诊断有时仍颇具挑战。其影像学特征可随时间推移发生变化甚至消失，这使得诊断过程易产生混淆。本研究旨在呈现3T HR-MRI下自发性未破裂颅内椎动脉夹层按病程分期的影像学表现，并基于各分期的特征性表现实现IVAD的病程时长估算。<b><i>方法:</i></b> 2011年1月至2014年7月期间，本研究回顾性纳入41支椎动脉（男:女=18:12；年龄范围32~67岁）。若患者的临床及影像学资料可明确发病起始时间，则诊断为自发性未破裂IVAD。基于既往已发表的研究，按照症状出现后的时间间隔将IVAD分为急性期（0~3天）、早期亚急性期（3~10天）、晚期亚急性期（10~60天）及慢性期（>60天，分为恢复组与未恢复组）。采用定性与定量方法，针对各分期的内膜瓣、双腔征、动脉瘤样扩张（包括最大外径、最大管壁厚度、管壁厚度指数及重构指数）、壁内血肿（相对信号强度）及血管壁强化情况，对HR-MRI表现进行评估与比较。由两名放射科医师通过阅片共识的方式分析HR-MRI影像结果。<b><i>结果:</i></b> 本研究纳入的IVAD病例中，急性期6例、早期亚急性期8例、晚期亚急性期16例、慢性期11例。从早期分期至慢性期，内膜瓣、双腔征、动脉瘤样扩张及壁内血肿等IVAD的HR-MRI典型表现均显著消退（p<0.05）。动脉瘤样扩张的量化指标及壁内血肿的相对信号强度在早期分期中数值最高，随后在慢性期恢复组中显著降低（p<0.05）。血管壁强化程度在早期分期中较高，至慢性期逐渐降低（p<0.05），但在症状出现后900天仍可观察到轻度血管壁强化。<b><i>结论:</i></b> 3T HR-MRI可清晰显示血管壁特征，能够区分自发性未破裂IVAD的早期分期与慢性期表现。基于病程分期的影像学特征表征，可为IVAD的病程时长估算提供辅助，同时有助于全面理解颅内椎动脉夹层的整体病程演变。