Utility of low kVp technique and contrast agent with reduced iodine content in enhanced chest CT: a preliminary study
GAO Zhi-peng, REN Xiao-yi, CUI Xiao-nan, MENG Dong-hua, WANG Jun, YE Zhao-xiang
Department of Radiology, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin 300060, China
Abstract：Objective: To evaluate the utility of low kVp technique and reduced iodine contrast agent in enhanced chest CT by comparison of radiation dose, enhancement, image quality and diagnostic accuracy. Methods: 200 patients with BMI<28 underwent enhanced chest CT examination, and were randomly divided into four groups(n=50 for each group): group A with 120 kVp and iohexol(Omnipaque, 300 mgI/mL), group B with 120 kVp and iodixanol(Visipaque, 270 mgI/mL), group C with 100 kVp and iohexol(Omnipaque, 300 mgI/mL) and group D with 100 kVp and iodixanol(Visipaque, 270 mgI/mL). The volume CT dose index(CTDIvol), the dose length product(DLP) were recorded and the effective rediation dose(ED) was calculated. Two radiologists evaluated subjective image quality with 4-points score. CT value and SD value for pulmonary artery were measured and the contrast to noise ratio(CNR) was calculated. The diagnostic accuracy was compared with pathological results for each group. Results: For 300 mgI/mL iohexol, the CT value of pulmonary artery in group A((204.9±32.4) HU) was 19.1% higher than that in group C((172.1±24.4) HU), for 270 mgI/mL iodixanol, the CT value of pulmonary artery in group A((188.7±26.0) HU) was 21.8% higher than that in group C((154.9±21.4) HU). The effective radiation doses for 100 kVp(group C (3.9±0.6) mSv and group D (3.9±0.8) mSv) were lower than 120 kVp (group A (4.8±1.3) mSv and group B (5.1±1.3) mSv)(P<0.01). Subjective image qualities for four groups all achieved the standards for diagnostics, and the scores for group A and group B were a little better than group C and group D. The scores of two radiologists were highly consistent(kappa=0.76±0.05). Compared with pathological results, the consistent rates for four groups ranged from 82.1% to 86.8% and had no significant difference. Conclusion: Combination of 100 kVp and 270 mgI/mL iodixanol in enhanced chest CT examination met the requirement of clinical diagnosis, and reduced 18.8% radiation dose.
2014, Vol. 25 
