| Part one Value of Dual-Energy Scan mode in preoperative T Staging evaluation of Gastric Cancer with Dual-energy CTObjective:To investigate the value of Dual-energy CT iodine measurement and spectral curve in the differentiation of T1 and T2-3 staged gastric cancer.Materials and methods:Imaging materials of 57 patients(36 men, 21 women, age range 27-79, mean age:57.66±12.78) pathologically proven gastric carcinoma before operation from October2014 to December 2015 were reviewed retrospectively,all patients underwent dual-energy scanning with SOMATOM Definition Flash CT.The dual-energy images were transported into the post processing application“ Liver VNC” to measure iodine concentration(IC) of the lesion and aorta of same level.The intramucosal and submucosal layer of stomach are defined as inner layer.The outer layer is outside the inner layer. Iodine concentration(IC) of inner layer, outer layer, normal stomach and aorta of same level were measured in arterial phase(AP) and venous phase(VP), and normalized iodine concentration(NIC) was calculated respectively. NIC was compared among inner layer, outer layer and normal stomach of T1 cases and T2-3cases in AP and VP by using One-way ANOVA. Then we can obtain advanced virtual monoenergetic imaging of 40 ~ 140 ke V by using another post processing application“Dual-energy Mono+” to measure the CT values of lesions on different energy level.Then analysis the spectrum curve feature of inner layer, outer layer and normal stomach.Results:Among 57 patients with gastric cancer, 26cases(16 men, 10 women) and 31cases(20men, 11 women) were diagnosed as T1 and T2-3 staging respectively by the pathology examination after the operation.NIC of inner layer, outer layer and normal stomach in T1 cases were0.297±0.042, 0.168±0.468, 0.184±0.487 and 0.790±0.074, 0.342±0.073, 0.374±0.058 respectively in AP and PP. There were significant differences in NIC between T1 inner layer and outer layer, between T1 inner layer and normal stomach in AP and PP(P<0.05). No significant differences were seen in NIC between T1 outer layer and normal stomach in AP and PP(P>0.05). Spectrum curve of T1 inner layer located above that of outer layer and normal stomach, and was more steep.Difference between these two curve became greater during 40 to 70 ke V, and became smaller with ke V increasing.NIC of inner layer, outer layer and normal stomach in T2-3 cases were0.314±0.040, 0.297±0.042, 0.182±0.028 and 0.747±0.070, 0.692±0.124, 0.368±0.041 respectively in AP and PP. There was significant difference in NIC between normal stomach and T2 inner layer, between normal stomach and T2 outer layer in AP and PP.No significant differences were seen in NIC between T2 inner layer and T2 outer layer AP and PP. Spectrum curve of T2 inner layer and outer layer located above that of normal stomach, and was more steep. Difference between these two curve became greater during 40 to 70 ke V, and became smaller with ke V increasing.Conclusion:The iodine measurement and the feature of the spectrum curve have certain value in the differentiation of T1 and T2-3 staged gastric cancer through the dual-energy model scan and was helpful to preoperative T staging of gastric cancer.Part two Application of dual-source CT advanced virtual monoenergetic imaging in early gastric cancerObjective:To investigate effect of advanced virtual monoenergetic imaging on image quality of early gastric cancer with dual-source CT.Materials and methods:Imaging materials of 26 cases(16 men, 10 women, age range 27-70, mean age:57.15±10.51) pathologically proven EGC from October 2014 to December 2015 were reviewed retrospectively, all patients underwent dual-energy scanning with SOMATOM Definition Flash CT. The dual-energy images of arterial phase and conventional 120 k Vp polychromatic images were transported into the post processing application. Advanced virtual monoenergetic images with energy levels at40 ke V, 50 ke V, 60 ke V and 70 ke V were reconstructed by using an advanced monoenergetic software application(syngo.via.VA30 A, Dual energy Mono+).Contrast-to-noise ratio(CNR) of lesion, image noise, overall image quality score and lesion conspicuity score were compared between different advanced virtual monoenergetic images and conventional polychromatic images at 120 k Vp by using One-way ANOVA and Kruskal-Wallis H test.Results:Among 26 patients with T1 gastric cancer, 9 intramucosal cancers and 17 submucosal cancers were confirmed by the pathology examination.CNR(3.24±0.76,2.94±0.92,2.47±0.79,2.37±0.98 and 1.22±0.40 respectively) and image noise[(32.7±1.82),(25.6±2.61),(20.30±2.17),(17.03±2.15) and(18.15±2.12)HU respectively] among 40 ke V, 50 ke V, 60 ke V, 70 ke V and 120 k Vp group all had statistical differences(F=24.654,227.05,both P<0.01). CNR in 50 ke V group was higher than that of 60 ke V, 70 ke V and 120 k Vp group, but similar to that of 40 ke V group(P>0.05).SD value in 50 ke V group was lower than that of 40 ke V group, but higher than that of the other three groups(all P<0.05). The overall image quality score[(3.08±0.27),(3.65±0.49),(3.31±0.47),(3.23±0.43) and(3.15±0.37) point, respectively] and lesion conspicuity score[(4.15±0.67),(3.92±0.48),(3.27±0.45),(3.08±0.27)and(3.04±0.20)point] among the five groups all had statistical differences(F=25.343,70.426,both P<0.01). The overall image quality score of 50 ke V group was higher than that of the other four groups(all P<0.05). Lesion conspicuity score in 50 ke V group was higher than that of 60 ke V, 70 ke V and 120 k Vp group and similar to that of 40 ke V group(P>0.05).Conclusion:The advanced virtual monoenergetic images can increase the CNR value of early gastric cancer while improving the overall image quality and can be used in the detection of the early gastric cancer and improve the image quality. |
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