ABSTRACT
Objective To explore the value of linear blending and non-linear blending images of dual-energy CT in improving the image quality of portal venography.Methods 60 patients clinically confirmed as liver cirrhosis with portal hypertension and gastric fundus esophageal varices were enrolled in the study.The patients underwent dual-energy (Sn140/80 kVp) scans in the portal phase, and four groups with 80 kVp and 140 kVp were defined as group A (linear blending images with M=0.3), B (linear ones with M=1.0), C (non-linear ones with c=150 and w=200) and D [non-linear ones with c=(CThepatic portal+CThepatic parenchymal)/2 and w=(CThepatic portal-CThepatic parenchymal)/2, and the CThepatic portal and CThepatic parenchymal were measured on M=0.3 image].The in portal vein enhancements, image noise, signal-to-noise ratio (SNR),contrast-to-noise ratio (CNR) and CT value difference between portal vein and liver parenchyma among four groups were compared by one-way ANOVA analysis of variance test.VRT imaging quality among four groups were assessed by Kruskal-Wallis test and Mann-Whitney U test.Results In four groups, the SNR and CNR of portal vein,and the CT value difference between portal vein and liver parenchyma(14.36 HU±3.23 HU,9.78 HU±2.39 HU,107.66 HU±21.28 HU) of group D were the highest (F=34.94,68.10 and 162.43,all P<0.01),and VRT image quality score of group D(4.78±0.42) was the best when compared to others (all P<0.01).Conclusion Non-linear blending technique of group D can improve the image quality of CT portography, which may be used in clinical practice.
ABSTRACT
OBJECTIVE: To determine whether non-linear blending technique for arterial-phase dual-energy abdominal CT angiography (CTA) could improve image quality compared to the linear blending technique and conventional 120 kVp imaging. MATERIALS AND METHODS: This study included 118 patients who had accepted dual-energy abdominal CTA in the arterial phase. They were assigned to Sn140/80 kVp protocol (protocol A, n = 40) if body mass index (BMI) or = 25. Non-linear blending images and linear blending images with a weighting factor of 0.5 in each protocol were generated and compared with the conventional 120 kVp images (protocol C, n = 37). The abdominal vascular enhancements, image noise, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and radiation dose were assessed. Statistical analysis was performed using one-way analysis of variance test, independent t test, Mann-Whitney U test, and Kruskal-Wallis test. RESULTS: Mean vascular attenuation, CNR, SNR and subjective image quality score for the non-linear blending images in each protocol were all higher compared to the corresponding linear blending images and 120 kVp images (p values ranging from < 0.001 to 0.007) except for when compared to non-linear blending images for protocol B and 120 kVp images in CNR and SNR. No significant differences were found in image noise among the three kinds of images and the same kind of images in different protocols, but the lowest radiation dose was shown in protocol A. CONCLUSION: Non-linear blending technique of dual-energy CT can improve the image quality of arterial-phase abdominal CTA, especially with the Sn140/80 kVp scanning.