Impact of scanning and reconstruction parameters on volume measurement of pulmonary ground glass nodules for phantom study / 中国介入影像与治疗学

ABSTRACT

Objective: To explore the effect of MSCT scanning and reconstruction parameters on volume measurement of phantom pulmonary ground glass nodules. Methods: Eight pulmonary ground glass nodules were scanned by different tube voltages (80 kV, 100 kV, 120 kV), tube currents (100 mA, 150 mA, 200 mA) by GE VCT. The original data in 150 mA, 80 kV group were reconstructed with different slice thickness (0.625 mm, 1.25 mm), reconstruction algorithm (soft, standard, lung, bone) and field of view (36 cm, 18 cm). The two independent chest radiologists measured the volume of ground glass nodules by lung nodule assessment software. The absolute percentage error (APE)= (|V measurement-V actual|) /Vactual×100% was analyzed statisticall. The consistency of volume measurements was evaluated by intraclass correlation coefficient (ICC). Results: There was great agreement of inter-observers in volume measurement of phantom pulmonary ground glass nodules (ICC=0.98). There was no significant difference in APE value among the nodules under different tube voltages (P>0.05), while the tube current was 150 mA and the APE value was the lowest (P0.05). As the reconstructed field decreased, the APE value decreased (P < 0.05). Different reconstruction algorithms had different effects on the APE value of nodules (P<0.05). The APE value in lung algorithm was smaller than that in the other algorithms. The APE values of low density and small nodules (CT value=-800 HU, diameter=5 mm) were higher than 10 under various conditions. Conclusion: 80 kV, 150 mA of scanning parameters combined with target reconstruction and lung algorithm can reduce the radiation dose and improve the accuracy of volume measurement of ground glass nodules in MSCT, and the pulmonary nodule analysis software is not suitable for the analysis of small ground glass nodules of lung.