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目的使用第二代Siemens双源CT对食管癌患者行双能双期增强扫描,获得食管癌病变、正常食管壁及图像噪声的能谱曲线,经计算获得病变的CNR、SNR曲线,寻找显示食管癌病变的最佳单能量(keV),并评价双期最佳单能量图像对食管癌病变的显示能力。方法使用第二代Siemens双源CT对37例食管癌患者行双能双期增强扫描,A球管管电压80 kVp,B球管管电压140 kVp,采用CARE DOSE 4D技术,经肘静脉注射对比剂70 ml后分别于第25 s(动脉期)及60 s(静脉期)行双能量扫描。应用“Monoenergetic”软件,使用1 mm层厚图像获得食管癌病变、正常食管壁及图像噪声的能谱曲线。经计算获得病变的CNR、SNR曲线,找到显示食管癌病变的最佳单能量(keV)。对照组为融合图像以及最佳单能量相邻的两个单能量图像。结果 (1)食管癌病变、正常食管壁的能谱曲线自低能量至高能量逐渐递减,食管癌病变的能谱曲线高于正常食管壁的能谱曲线。(2)动脉期、静脉期显示病变的最佳单能量(keV)均出现在70 keV,病变的CNR、SNR曲线的最大值均出现在70 keV;图像噪声最小值均出现在70 keV。(3)70 keV条件下动脉期病变的CNR大于静脉期,而静脉期病变的SNR大于动脉期。结论显示食管癌病变的最佳单能量出现在70 keV,动脉期对于病变的显示具有较大的优势,而静脉期对于显示食管癌病变内部结构及与周围组织关系具有较大优势。
Objective To evaluate the CNR and SNR curves of esophageal cancer patients with esophageal cancer lesions, normal esophageal wall and image noise by using second-generation Siemens dual-source CT in patients with esophageal cancer. Esophageal cancer lesions the best single energy (keV), and evaluate the best dual-phase single-energy images of esophageal lesions display ability. Methods A total of 37 patients with esophageal cancer underwent dual-phase and double-phase contrast-enhanced CT scan with a second-generation Siemens dual-source CT. The voltage of the A-tube was 80 kVp and the voltage of the B-tube was 140 kVp. CARE DOSE 4D A dose of 70 ml was used for dual-energy scanning at 25 s (arterial phase) and 60 s (venous phase) respectively. Using the “Monoenergetic” software, the energy spectrum of esophageal cancer lesions, normal esophageal wall and image noise was obtained using a 1 mm layer thickness image. The CNR and SNR curves of the lesions were calculated to find the optimal single energy (keV) for showing lesions of esophageal cancer. The control group was fused image and two single energy images with the best single energy adjacent. Results (1) The esophageal cancer lesions, normal esophageal wall energy spectrum curve from low energy to high energy gradually decreased esophageal cancer spectrum of energy spectrum is higher than normal esophageal wall energy spectrum curve. (2) The best single energy (keV) of lesions showed in arterial phase and venous phase all appeared at 70 keV. The maximal CNR and SNR curves of all the lesions appeared at 70 keV. The minimum image noise appeared at 70 keV. (3) The CNR of arterial phase was higher than that of venous phase at 70 keV, while the SNR of venous phase was larger than that of arterial phase. The results showed that the optimal single energy of esophageal cancer appeared in 70 keV, the arterial phase showed a greater advantage for the lesion, while the venous phase of esophageal lesions showed that the internal structure and the relationship with the surrounding tissue has a greater advantage.