Effects of Dual-Energy CT with Non-Linear Blending on Abdominal CT Angiography

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.

Study on the feasibility of abdominal aortic CT angiography with low dose contrast medium / 中华放射学杂志

ObjectiveTo study the feasibility of abdominal aortic CT angiography with low dose contrast medium.MethodsThe patients who took the examinations were divided into three groups.In 34 patients of group A,the injection flow rate was 4 ml/s,and the contrast medium volume was 90 ml and 20 ml of saline was applied.The contrast medium dose and injection flow rate of the other 64 patients were determined according to the formula,injection tlow rate = patients' body mass × ratio of contrast medium dose to the body mass / (5 + exposure time).In B and C group with 32 cases each,the ratio of contrast medium dose to body mass were 0.8 to 0.9 and 0.6 to 0.7 ml/kg.The depiction and the measured intraarterial concentration of contrast medium of the abdominal aorta and the renal arteries as well as their branches were compared and evaluated on the source images and MIP images generated among three groups respectively.CT values of the abdominal aorta and its branches in each group were analyzed using singlefactor analysis of variance,while renal artery and its branches were analyzed using x2 test score.Results The abdominal aorta,the celiac trunk,the splenic artery,the superior mesenteric artery,the renal arteries and their branches were all well shown in three groups.The CT value within the abdominal aorta were (363 ±28),(362 ±28) and (334 ± 14) HU for the three groups respectively,the CT values within the celiac were (368 ±28),(367 ±28) and (338 ± 15)HU,the CT value within the renal artery were (365 ±27),(364 ± 29) and (336 ± 15) HU respectively,the CT value within the splenic artery were (373 ±28),(372 ± 28) and (343 ± 15) HU respectively,and the CT value within the superior mesenteric artery were ( 374 ± 28 ),( 372 ± 28 ) and ( 344 ± 16 ) HU respectively.There were significant differences among the three groups ( P = 0.000).There were significant differences between A group and C group,B group and C group ( P ＜ 0.01 ),while no significant difference existed between A group and B group( P ＞0.05 ).The amount of contrast agent for each patient in group A was 90 ml,while the amount of contrast agent in group B and C was (51 ± 9) and (40 ± 9) ml respectively.There were significant differences of the contrast medium volume among the three groups ( F = 537.091,P = 0.000).Results of pairwise comparisons were statistically significant(P =0.000).Image quality of renal artery in group A was rated as excellent,good,and generally for 26,7 and 1 cases,24,7 and 1 for group B,and 22,8 and 2 for group C.There were no significant differences in image quality of the renal arteries among the three groups ( x2 = 0.561,P = 0.755 ).ConclusionThe individualization of injection method in abdominal aortic CT angiography can minimize the amount of contrast agent but to meet the clinical requirements.

Preoperative evaluation of left gastric artery by 64-slice spiral CT angiography in gastric cancer patients / 中华普通外科杂志

ObjectiveTo delineate the anatomy of left gastric artery (LGA) by CT imaging before radical gastrectomy in gastric cancer patients to facilitate intraoperative N07 lymph node dissection.MethodsPreoperative 64 spiral CT angiography (CTA) was applied to observe the origin and course of LGA in gastric cancer patients.ResultsThere were 731 gastric cancer patients undergoing preoperative image evaluation with LGA origin identified from celiac axis in 635 cases. Among those, LGA originated respectively at the crotch of splenic artery and common hepatic artery in 176 cases, from the proximal 1/3 in 292 cases, middle 1/3 in 135 cases and distal 1/3 in 32 cases. There were 9, 28, 27, 4, 4, 1, 4 and 1 cases in whom LGA originates respectively at the angle between celiac trunk and abdominal aorta, from the abdominal aorta, arteria gastrolienalis, splenic artery, common hepatic artery, left hepatic artery, artery gastrohepatica and superior mensentaric artery. LGA has not been observed in 15 cases and the origination of LGA could not be delineated in 3 cases. ConclusionsBeing familiar with the anatomy of LGA as visualized by preoperative CTA in gastric cancer patient, facilitates lymph node dissection around the LGA and decreases iatrogenic injury to vital blood vessels.