双源CT双能量扫描显示胃癌的图像质量及迭代重建算法降低图像噪声的能力

目的评价不同管电压条件下双源CT(DECT)双能量扫描显示胃癌的图像质量及迭代重建成像(IRIS)技术降低图像噪声的能力。方法采用双源CT双能模式对60例经胃镜活检证实的胃癌患者行上腹平扫及双期增强扫描,获取不同管电压下的图像及融合图像;分别以FBP算法和IRIS算法重建图像,对不同算法下的CT值的差值和SNR进行统计学分析。结果动脉期和静脉期FBP-80kVp与FBP-DE图像中,胃癌与正常胃壁CT值差异有统计学意义(Z=-2.02、-2.29,P=0.04、0.02)。动脉期和静脉期FBP-80kVp与IRIS-80kVp图像的胃癌噪声、肝脏噪声差异均有统计学意义(P均<0.01)。动脉期FBP融合图像(FBP-DE)与IRIS-80kVp图像中的肝脏SNR差异无统计学意义(Z=-0.33,P=0.75),而动脉期FBP-DE与IRIS-80kVp图像中的胃癌SNR和静脉期胃癌及肝脏SNR差异均有统计学意义(P均<0.01)。结论 80kVp图像显示胃癌与正常胃壁间的CT值差异较好,有利于显示病变;利用IRIS技术可降低图像噪声,低电压与IRIS重建相结合可提高图像SNR。

Evaluating images quality of gastric cancer with dual-energy CT and noise reduction capability with iterative reconstruction in image space

Objective To evaluate imaging quality of different tube voltage conditions by using dual-energy CT (DECT) scanning in gastric cancer patients, and to observe noise reduction capability using iterative reconstruction in image space (IRIS). Methods Sixty patients with gastric cancer confirmed by endoscopy underwent DECT scan. Enhanced scan was performed using DECT with dual energy mode in all patients. The images of different voltage conditions and intergrated images were gotten. All images were reconstructed with filtered back projection (FBP) and IRIS. The differences of CT value and SNR were statistically analyzed. Results Both in the arterial and venous phase images, there were significantly statistical differences between gastric cancer and normal gastric wall under 80 kVp and FDP-DE (Z=-2.02, -2.29; P=0.04, 0.02). There were significantly statistical differences in the image of tumor and liver obtained in the arterial and venous phase between FBP-80 kVp and IRIS-80 kVp (all P<0.05), also between significant FBP-DE and IRIS-80 kVp images (all P<0.01), except SNR of the liver in arterial phase images (Z=-0.33, P=0.75). Conclusion The images of the low voltage (80 kVp) can display the difference of CT values between the tumor and the normal gastric wall, and IRIS can reduce the noise. Combination of low voltage and IRIS can make the image optimized.