Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
Department of Clinical Epidemiology and Biostatistics, and Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
Thyroid. 2021 Mar;31(3):452-458. doi: 10.1089/thy.2020.0317. Epub 2021 Jan 18.
Active surveillance is recommended as an alternative to immediate surgery for low-risk papillary thyroid microcarcinoma (PTMC), and determining meaningful changes in diameter and volume on ultrasonography (US) is critical. However, interobserver reproducibility of the sonographic measurement of maximum diameter and volume of PTMC has not been well established. We aimed to determine the reproducibility in the measurement of maximum diameter and volume of PTMC on US. Consecutive patients who underwent US for pathologically proven PTMC between December 2018 and December 2019 were retrospectively reviewed. Two observers independently performed sonographic measurement of each nodule using standardized measurement methods. Each observer measured maximum transverse, anteroposterior, and longitudinal nodule diameters, and using these, nodule volume was calculated using the ellipsoid formula. Interobserver reproducibility in the measurement of the maximum diameter and volume was assessed using percentage reproducibility coefficient (RC). Z-tests of the intraclass correlation coefficients (ICCs) were used to compare the interobserver reproducibility in subgroups defined according to sonographic characteristics, such as the presence of microcalcification, nodule size, and parenchymal heterogeneity. A total of 197 thyroid nodules from 188 patients were included in the study series. The percentage RCs were 71.8% [95% confidence interval, CI 65.4-79.7%] and 23.7% [CI 21.6-26.3%] for volume and maximum diameter measurements, respectively. There were no significant differences noted in the ICC values according to nodule orientation, presence of calcifications, size, or parenchymal heterogeneity. For PTMC, a difference of up to 24% in the maximum diameter and 72% in the volume may be considered to be within measurement error on US. This value may be used to determine the cutoff for defining meaningful change in the maximum diameter and volume for PTMC during active surveillance.
主动监测被推荐作为低危型甲状腺微小乳头状癌（PTMC）的一种替代治疗方法，因此，准确评估超声（US）测量的肿瘤最大直径和体积的变化具有重要意义。然而，PTMC 的超声测量的最大直径和体积的观察者间重复性尚未得到很好的证实。我们旨在确定 PTMC 的 US 测量最大直径和体积的重复性。
回顾性分析了 2018 年 12 月至 2019 年 12 月期间因病理证实的 PTMC 而接受 US 检查的连续患者。两名观察者分别采用标准化的测量方法对每个结节进行超声测量。每位观察者测量结节的最大横径、前后径和长径，并使用这些径线通过椭球公式计算结节体积。使用百分比重复性系数（RC）评估最大直径和体积测量的观察者间重复性。使用组内相关系数（ICC）的 Z 检验比较根据超声特征（如微钙化、结节大小和实质异质性）定义的亚组之间观察者间重复性。
共有 188 例患者的 197 个甲状腺结节纳入本研究系列。体积和最大直径测量的 RC 百分比分别为 71.8%（95%可信区间：65.4%-79.7%）和 23.7%（95%可信区间：21.6%-26.3%）。根据结节方位、钙化、大小或实质异质性，ICC 值没有显著差异。
对于 PTMC，最大直径和体积的差异分别高达 24%和 72%，可被认为是 US 测量误差范围内的变化。该值可用于确定主动监测期间 PTMC 最大直径和体积的有意义变化的截止值。
