目的:对于前庭神经鞘瘤(VS)患者,保守的观察方法越来越多地被使用。因此,需要准确和可靠的体积肿瘤监测是重要的。目前,肿瘤体积增加20%的体积截止值广泛用于定义VS中的肿瘤生长。该研究通过观察者间研究调查了肿瘤体积对VS体积测量的一致性极限(LoA)的依赖性。
方法:这项回顾性研究纳入了100例VS患者,这些患者接受了对比增强T1加权MRI。五个观察者对图像进行了体积注释。观察者协议和可靠性是使用LoA衡量的,使用与平均值(LOAM)方法的一致性极限进行估计,和组内相关系数(ICC)。
结果:100名患者的中位平均肿瘤体积为903mm3(IQR:193-3101)。根据肿瘤体积四分位数将患者分为四个体积大小类别。最小的肿瘤体积四分位数显示相对于26.8%的平均值的LOAM(95%CI:23.7-33.6),而对于最大肿瘤体积的四分位数,这一数字为7.3%(95%CI:6.5~9.7),当排除瘤周囊肿时,这一数字为4.8%(95%CI:4.2~6.2).
结论:VS的体积注释内的协议限制受肿瘤体积的影响,因为LoA随着肿瘤体积的增加而改善。因此,对于大于200mm3的肿瘤,可以在早期可靠地检测到生长,与目前广泛使用的20%的截止值相比。然而,对于非常小的肿瘤,应该用比以前认为的更高的协议限制来评估增长。
OBJECTIVE: For patients with vestibular schwannomas (VS), a conservative observational approach is increasingly used. Therefore, the need for accurate and reliable volumetric tumor monitoring is important. Currently, a volumetric cutoff of 20% increase in tumor volume is widely used to define tumor growth in VS. The study investigates the tumor volume dependency on the limits of agreement (LoA) for volumetric measurements of VS by means of an inter-observer study.
METHODS: This retrospective study included 100 VS patients who underwent contrast-enhanced T1-weighted MRI. Five observers volumetrically annotated the images. Observer agreement and reliability was measured using the LoA, estimated using the limits of agreement with the mean (LOAM) method, and the intraclass correlation coefficient (ICC).
RESULTS: The 100 patients had a median average tumor volume of 903 mm3 (IQR: 193-3101). Patients were divided into four volumetric size categories based on tumor volume quartile. The smallest tumor volume quartile showed a LOAM relative to the mean of 26.8% (95% CI: 23.7-33.6), whereas for the largest tumor volume quartile this figure was found to be 7.3% (95% CI: 6.5-9.7) and when excluding peritumoral cysts: 4.8% (95% CI: 4.2-6.2).
CONCLUSIONS: Agreement limits within volumetric annotation of VS are affected by tumor volume, since the LoA improves with increasing tumor volume. As a result, for tumors larger than 200 mm3, growth can reliably be detected at an earlier stage, compared to the currently widely used cutoff of 20%. However, for very small tumors, growth should be assessed with higher agreement limits than previously thought.