Dual-source CT energy spectral imaging in qualitative evaluation of metastatic lymph nodes in patients with gastric cancer / 中国医学影像技术

ABSTRACT

Objective To observe the value of dual-source CT energy spectral imaging in qualitative evaluation of metastatic lymph nodes in patients with gastric cancer.Methods Data of patients with pathologically diagnosed gastric cancer were collected,who underwent both dual-source CT abdomen plain scanning and energy spectrum double-phase enhanced scanning.The long diameter,short diameter,short length-diameter ratio,arterial phase and venous phase standardized iodine concentration of lymph nodes were measured and recorded.Energy spectrum attenuation curves were drawn,and the slopes were calculated.Parameters with statistical significant differences between metastatic and non-metastatic lymph nodes were used to plot ROC curves,and the thresholds for diagnosing metastatic lymph nodes of gastric cancer,and their diagnostic sensitivity and specificity were calculated.Results There were significant differences in short axis,short aspect ratio,normalized iodine concentration in arterial phase and venous phase between metastatic and non-metastatic lymph nodes in patients with gastric cancer (all P＜0.05),the area under the curve of ROC curve was 0.601 (P=0.006),0.881 (P＜0.001),0.865 (P＜0.001) and 0.834 (P＜0.001),respectively.When the short length to diameter ratio was 0.730,the sensitivity and specificity in diagnosis of metastatic lymph nodes of gastric cancer was 75.72％ and 93.64％.When standardized iodine concentration was 0.223 in arterial phase,the sensitivity and specificity in diagnosis of metastatic lymph nodes of gastric cancer was 69.81％ and 91.20％.When the standardized iodine concentration was 0.392 in the venous phase,the sensitivity and specificity in diagnosis of metastatic lymph nodes of gastric cancer was 78.33％ and 85.63％.Dual-phase energy spectrum curve of both gastric metastatic lymph nodes and non-lymph node decreased.Taken the arterial curve slope k=6.860 as the threshold,the sensitivity and specificity in diagnosis of metastatic lymph nodes was 83.24％ and 84.72％.When the threshold venous phase slope k was set at 6.660,the sensitivity and specificity in diagnosis of metastatic lymph nodes was 64.62％ and 97.70％,respectively.Combining arterial phase length-to-diameter ratio,arterial phase standardized iodine concentration and spectral curve slope,the sensitivity and specificity in diagnosing metastatic lymph nodes was 97.34 ％ and 87.83 ％,which was 80.13 ％ and 90.31％ when combining venous phase short length-diameter ratio,venous phase standardized iodine concentration and spectral curve slope.Conclusion The short-length-to-diameter ratio,arterial-venous phase standardized iodine concentration and arterial-venous phase slope of lymph nodes are the main parameters for evaluating metastatic lymph nodes in patients with gastric cancer.Combination of the above three parameters can obviously improve the sensitivity and specificity in diagnosis of metastatic lymph nodes in patients with gastric cancer.