Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
Korean J Radiol. 2020 Jun;21(6):756-763. doi: 10.3348/kjr.2019.0789.
To evaluate the effects of attenuation threshold on CT pulmonary vascular volume ratios in children and young adults with congenital heart disease, and to suggest an optimal attenuation threshold.
CT percentages of right pulmonary vascular volume were compared and correlated with percentages calculated from nuclear medicine right lung perfusion in 52 patients with congenital heart disease. The selected patients had undergone electrocardiography-synchronized cardiothoracic CT and lung perfusion scintigraphy within a 1-year interval, but not interim surgical or transcatheter intervention. The percentages of CT right pulmonary vascular volumes were calculated with fixed (80-600 Hounsfield units [HU]) and adaptive thresholds (average pulmonary artery enhancement [PA] divided by 2.50, 2.00, 1.75, 1.63, 1.50, and 1.25). The optimal threshold exhibited the smallest mean difference, the lowest -value in statistically significant paired comparisons, and the highest Pearson correlation coefficient.
The PA value was 529.5 ± 164.8 HU (range, 250.1-956.6 HU). Results showed that fixed thresholds in the range of 320-400 HU, and adaptive thresholds of PA/1.75-1.50 were optimal for quantifying CT pulmonary vascular volume ratios. The optimal thresholds demonstrated a small mean difference of ≤ 5%, no significant difference (> 0.2 for fixed thresholds, and > 0.5 for adaptive thresholds), and a high correlation coefficient (0.93 for fixed thresholds, and 0.91 for adaptive thresholds).
The optimal fixed and adaptive thresholds for quantifying CT pulmonary vascular volume ratios appeared equally useful. However, when considering a wide range of PA, application of optimal adaptive thresholds may be more suitable than fixed thresholds in actual clinical practice.
评估衰减阈值对先天性心脏病患儿和年轻成人 CT 肺血管容积比的影响，并提出一个最佳的衰减阈值。
比较了 52 例先天性心脏病患者 CT 右肺血管容积百分比与核医学右肺灌注计算的百分比，并进行相关性分析。这些患者在 1 年内接受了心电图同步的心胸 CT 和肺灌注闪烁显像检查，但在此期间未接受手术或经导管干预。使用固定（80-600 亨氏单位[HU]）和自适应阈值（平均肺动脉增强[PA]除以 2.50、2.00、1.75、1.63、1.50 和 1.25）计算 CT 右肺血管容积百分比。最佳阈值的平均差异最小，统计学上显著配对比较的低值最低，皮尔逊相关系数最高。
PA 值为 529.5 ± 164.8 HU（范围，250.1-956.6 HU）。结果表明，固定阈值范围为 320-400 HU，自适应阈值为 PA/1.75-1.50 时，用于量化 CT 肺血管容积比的最佳。最佳阈值的平均差异较小，均≤5%，无显著差异（固定阈值>0.2，自适应阈值>0.5），相关性较高（固定阈值为 0.93，自适应阈值为 0.91）。
最佳的固定和自适应阈值对于量化 CT 肺血管容积比同样有效。然而，在考虑广泛的 PA 时，在实际临床实践中，应用最佳的自适应阈值可能比固定阈值更合适。
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