The effect of CT reconstruction kernels and display window settings on the detection and measurement of pulmonary solid nodules / 西安交通大学学报(医学版)

ABSTRACT

【Objective】 To assess the effect of reconstruction kernels and window settings on the detection and measurement of pulmonary solid nodules and their measurement variability and repeatability. 【Methods】 We retrospectively recruited 49 patients with pulmonary solid nodules who had undergone low-dose CT scanning. Images were reconstructed using five reconstruction kernels： lung， bone， chest， detail and standard kernels. Two radiologists independently assessed the detection rate， diameter and CT number measurement of nodules under the five kernels and two window settings （lung-window and mediastinal-window）. Bland-Altman plots and relative average deviation （RAD） were used to evaluate the repeatability and variability of nodule diameter and CT number measurement. 【Results】 Seventy-seven nodules were detected on lung-window regardless of reconstruction kernels， while the detection rates （75.3%-98.7%） were significantly different （P<0.001） on the mediastinal-window， with the lung kernel significantly improving the detection of nodules with the diameter below 6 mm. In both display windows， the diameter and CT number measurements among reconstruction kernels were similar except for the lung kernel. The lung-window had better variability in the diameter measurement while mediastinal-window was better in CT number measurement among various reconstruction kernels. Although the variability in the diameter of the nodule on the lung-window and mediastinal-window was similar， there was a significant difference in the variability in the diameter measurement among different reconstruction kernels on the mediastinal-window （P=0.004）. No significant difference in the variability in the CT number measurement was found among the different reconstruction kernels （lung-window P=0.163； mediastinal-window P=0.201）， and the variability in the CT number measurements on the mediastinal-window was smaller than that of the lung-window. Both window displays had acceptable repeatability in diameter and CT number measurement； however， the mediastinal-window was better in CT number measurement. 【Conclusion】 The lung kernel can improve the detection of pulmonary solid nodules below 6 mm， but is limited in the CT number measurement. The lung-window display provides better variability in measuring nodule diameter， while mediastinal-window display is better at measuring CT numbers.