Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong SAR, China.
J Stroke Cerebrovasc Dis. 2013 Nov;22(8):e615-9. doi: 10.1016/j.jstrokecerebrovasdis.2013.07.036. Epub 2013 Sep 25.
Changes of signal intensities (SIs) across intracranial atherosclerosis (ICAS) on magnetic resonance angiography (MRA) may reflect hemodynamic impact of the lesion. We evaluated the interobserver reproducibility of an index termed signal intensity ratio (SIR), developed in a previous study to represent the changes of SIs across ICAS on MRA.
Symptomatic ICAS on MRA were retrospectively recruited. Two observers respectively evaluated the images and calculated the SIR as follows, blinded to each other's readings: SIR=(mean poststenotic SI-mean background SI)/(mean prestenotic SI-mean background SI). Statistical analyses were performed to evaluate the interobserver reproducibility of this index.
A total of 102 symptomatic ICASs were enrolled, with 36 (35.3%) lesions of 50%-69% MRA stenoses and others being 70%-99% stenoses or flow void on MRA. Overall, mean SIRs were not significantly different between the 2 observers (.92±.17 versus .93±.17; mean difference -.006±.09; P=.496 for paired t test). Pearson correlation coefficients were >.80 for all analyses, indicating strong linear correlations between SIRs by the 2 observers. Bland-Altman analysis for SIRs of all cases showed no systematic bias between the 2 observers. For different cut-points ranging from .75 to 1.00, the kappa statistics were mostly greater than .6 and interobserver agreements were all greater than 80%, implying substantial agreement between observers.
SIR was demonstrated to be highly reproducible between observers in the present study. Future studies are warranted to further explore the role of this index in comprehensive evaluation and risk stratification of symptomatic ICAS.
磁共振血管造影（MRA）上颅内动脉粥样硬化（ICAS）信号强度（SI）的变化可能反映病变的血流动力学影响。我们评估了之前研究中提出的一种名为信号强度比（SIR）指数的观察者间可重复性，该指数用于代表 MRA 上 ICAS 处 SI 的变化。
回顾性招募 MRA 上有症状的 ICAS。两名观察者分别评估图像并计算 SIR，彼此的读数均为盲法：SIR=(poststenotic SI 均值-background SI 均值)/(prestenotic SI 均值-background SI 均值)。进行统计学分析以评估该指数的观察者间可重复性。
共纳入 102 例有症状的 ICAS，其中 36 个（35.3%）病变的 MRA 狭窄程度为 50%-69%，其余病变为 70%-99%狭窄或 MRA 上的血流缺失。总体而言，两名观察者之间的平均 SIR 没有显著差异（.92±.17 与.93±.17；平均差值-.006±.09；配对 t 检验 P=.496）。所有分析的 Pearson 相关系数均>.80，表明两名观察者之间的 SIR 具有很强的线性相关性。对所有病例的 SIR 进行 Bland-Altman 分析，两名观察者之间没有系统偏差。对于从.75 到 1.00 的不同截断值，kappa 统计量大多大于.6，观察者间的一致性均大于 80%，表明观察者之间存在高度一致。
本研究表明 SIR 在观察者之间具有高度可重复性。需要进一步研究来探索该指数在有症状的 ICAS 综合评估和危险分层中的作用。
