Abstract Infrared thermography is a non-invasive and non-ionizing imaging technique for recording body surface temperature. Considerable research efforts have been made to ensure that thermography in human medicine is performed to consistent standards so that measurements are traceable, reliable and valid, but interest in understanding sources of measurement uncertainty has developed less rapidly in veterinary thermography. The objective of our study was to understand the influence of variability in thermal imager performance, and the contribution to measurement variance of operator-dependent factors, in a practical equine thermography setting. The study employed five different models of thermal imager, which were all quality assured against a blackbody source prior to equine measurements. Three standard thermographic views were then obtained from nine clinically healthy horses using all five thermal imagers, with each imager capturing all views twice. On every thermographic image, regions of interest (ROIs) were then determined by two analyzers. The thermograms from each imager were assessed for their clinical utility. Agreement between analyzers of the same images, and between pairs of repeated images for the same analyzer, was assessed by Bland Altman plots. The contribution to the total variance in temperature measurements from analyzers and from camera-dependent factors was evaluated by ANOVA gauge R&R (reliability and reproducibility) analysis. Two of the thermal imagers produced readings during quality assurance which were outside of their stated specifications for accuracy. There were notable differences in the ability of the imagers to produce clinically useful thermograms, and it was difficult to compare the thermograms from different manufacturers due to the varied color palettes employed. Assessing agreement between analyzers, the bias was −0.05 °C and limits of agreement were 0.11 °C (upper) and −0.21 °C (lower). Agreement between repeated images was less good than between analyzers: the bias was 0.17 °C and limits of agreement were 1.55 °C (upper) and −1.21 °C (lower) for the first analyzer. Across all horses, the contribution by the analyzers to variance in temperature measurement at the ROIs from the lateral whole-body view was 9.8 ± 4.2% (Mean ± SD), for the lateral and medial aspects of the limbs was 26.5 ± 18.2%, and for the dorsal aspect of the limbs was 11.2 ± 9.2%. Across all ROIs and horses, the mean contribution to variance in the measurements from camera factors was 82.7 ± 15.3%. The work shows the importance of specifying an appropriate thermal imager for equine studies, and ensuring there is a programme of quality assurance in place for all devices used.

中文翻译：

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马热成像中的热像仪性能和图像分析可重复性

摘要 红外热成像是一种非侵入性、非电离的成像技术，用于记录体表温度。已经进行了大量研究以确保人类医学中的热成像按照一致的标准进行，以便测量可追溯、可靠和有效，但对了解测量不确定性来源的兴趣在兽医热成像中发展得较慢。我们研究的目的是了解热像仪性能可变性的影响，以及在实际马热成像设置中操作员相关因素对测量方差的贡献。该研究采用了五种不同型号的热像仪，在对马进行测量之前，所有型号都针对黑体源进行了质量保证。然后使用所有五台热像仪从九匹临床健康的马身上获得三个标准热成像视图，每个热像仪捕获所有视图两次。在每个热成像图像上，感兴趣的区域 (ROI) 然后由两个分析仪确定。评估来自每个成像仪的热谱图的临床效用。相同图像的分析器之间以及同一分析器的重复图像对之间的一致性通过 Bland Altman 图进行评估。通过 ANOVA 仪表 R&R（可靠性和再现性）分析评估分析仪和相机相关因素对温度测量总方差的贡献。其中两台热像仪在质量保证期间产生的读数超出了其规定的准确度规格。成像仪生成临床有用的热谱图的能力存在显着差异，并且由于使用的调色板不同，很难比较来自不同制造商的热谱图。评估分析仪之间的一致性，偏差为 -0.05 °C，一致性限制为 0.11 °C（上限）和 -0.21 °C（下限）。重复图像之间的一致性不如分析仪之间好：第一个分析仪的偏差为 0.17 °C，一致性限制为 1.55 °C（上限）和 -1.21 °C（下限）。在所有马匹中，分析仪对侧面全身视图 ROI 温度测量方差的贡献为 9.8 ± 4.2%（平均值 ± SD），四肢的外侧和内侧方面为 26.5 ± 18.2%，四肢背侧为 11.2 ± 9.2%。在所有投资回报率和马匹中，相机因素对测量方差的平均贡献为 82.7 ± 15.3%。这项工作显示了为马研究指定合适的热像仪的重要性，并确保为所有使用的设备制定质量保证计划。