Division of Cardiovascular Medicine, University of Cambridge, Cambridge, UK.
Circ Cardiovasc Imaging. 2012 Jan;5(1):86-93. doi: 10.1161/CIRCIMAGING.111.965442. Epub 2011 Nov 22.
Recent studies show that virtual histology intravascular ultrasound (VH-IVUS) can identify plaques at high risk of rupture, such as thin-capped fibroatheromata, raising the possibility of immediate targeted intervention. However, plaque classification entails border recognition and subjective assessment of plaque architecture, introducing inter-observer variability without confirmation by core-labs. Furthermore, the accuracy of local versus core-laboratory VH-IVUS plaque classification and effects of different plaque definitions have not been examined.
Local observers classified 100 VH-IVUS-defined coronary plaques to determine single center inter-observer variability; multi-center variability was determined by comparison with VH-IVUS core-laboratory analysis, and compared with gray-scale IVUS. Frequency of plaque types using different published plaque definitions also was determined. Single-center VH-IVUS inter-observer agreement was strong (kappa=0.86), but lower for thin-capped fibroatheromatas (k=0.59) because of observer judgments on presence and location of confluent necrotic core. Multi-center inter-observer agreement for plaque classification was lower again (k=0.71), particularly for thin-capped fibroatheromatas (k=0.56). Different plaque definitions further reduced VH-IVUS-defined thin-capped fibroatheromata numbers by 44%. The diagnostic accuracy of gray-scale IVUS to identify thin-capped fibroatheromata was poor for both observers (21 and 29% correct), with low inter-observer agreement (k=0.14).
VH-IVUS plaque classification, and particularly VH-IVUS-defined thin-capped fibroatheromata identification, varies significantly between local observers, and particularly in comparison with core-laboratory analysis. Differences in VH-IVUS plaque definitions introduce further variability between studies. These factors reduce the use of VH-IVUS plaque classification to guide intervention in a "live" clinical setting, and also affect comparison of diagnostic accuracy and natural history of plaques between studies.
最近的研究表明，虚拟组织学血管内超声（VH-IVUS）可以识别易破裂的斑块，如薄帽纤维粥样斑块，从而提高了立即进行靶向干预的可能性。然而，斑块分类需要边界识别和对斑块结构的主观评估，这会引入观察者间的变异性，而这种变异性未经核心实验室确认。此外，局部与核心实验室 VH-IVUS 斑块分类的准确性以及不同斑块定义的影响尚未得到检验。
当地观察者对 100 个 VH-IVUS 定义的冠状动脉斑块进行分类，以确定单中心观察者间的变异性；通过与 VH-IVUS 核心实验室分析进行比较来确定多中心变异性，并与灰阶 IVUS 进行比较。还确定了不同斑块定义下斑块类型的频率。单中心 VH-IVUS 观察者间的一致性很强（kappa=0.86），但薄帽纤维粥样斑块的一致性较低（kappa=0.59），因为观察者对融合性坏死核心的存在和位置的判断。斑块分类的多中心观察者间的一致性再次降低（kappa=0.71），特别是薄帽纤维粥样斑块（kappa=0.56）。不同的斑块定义进一步减少了 VH-IVUS 定义的薄帽纤维粥样斑块数量 44%。观察者对灰阶 IVUS 识别薄帽纤维粥样斑块的诊断准确性都较差（21%和 29%正确），观察者间的一致性也较低（kappa=0.14）。
VH-IVUS 斑块分类，特别是 VH-IVUS 定义的薄帽纤维粥样斑块的识别，在当地观察者之间以及与核心实验室分析之间存在显著差异。VH-IVUS 斑块定义的差异进一步增加了研究之间的变异性。这些因素降低了 VH-IVUS 斑块分类在“实时”临床环境中指导干预的应用，也影响了研究之间斑块的诊断准确性和自然史的比较。
