Qing Zhang1, Haifeng Mi1, Xubo Shi2, Wei Li1, Senlin Guo1, Ping Wang1, Hongna Suo1, Ziyi Wang1, Shanshan Jin3, Fei Yan1, Yantao Niu1, Junfang Xian4. 1. Department of Radiology, Beijing Tongren Hospital, Capital Medical University, No. 1 Dongjiaomin lane, Dongcheng District, Beijing 100730, P.R. China. 2. Department of Cardiology, Beijing Tongren Hospital, Capital Medical University, Beijing, P.R. China. 3. Beijing Institute of Ophthalmology, Beijing Tongren Hospital, Capital Medical University, Beijing, P.R. China. 4. Department of Radiology, Beijing Tongren Hospital, Capital Medical University, No. 1 Dongjiaomin lane, Dongcheng District, Beijing 100730, P.R. China. Electronic address: cjr.xianjunfang@vip.163.com.
Abstract
RATIONALE AND OBJECTIVES: To test whether higher iodine concentration together with higher noise level could lead to a further dose reduction in an already low dose coronary CT angiography (CCTA) protocol without comprising image quality. MATERIALS AND METHODS: One hundred eighty patients with suspected coronary artery disease (CAD) were randomly assigned into three groups: (a) conventional dose (CD) group, 100 kV with a noise index (NI) of 25 and iohexol (350 mg I/ml); (b) low dose (LD) group, 80 kV with a NI of 25 and iohexol (350 mg I/ml); (c) further low dose (FLD) group, 80 kV with a NI of 30 and iomeprol (400 mg I/ml). The volume and injection rate of contrast medium were fixed at 60 ml and 5 ml/s. The radiation dose (volume CT dose index [CTDIvol], dose length product [DLP], and effective dose [ED]) were recorded. For image quality, both quantitative (enhancement, noise, signal-to-noise ratio [SNR], and contrast-to-noise ratio [CNR]) and qualitative indices were assessed. RESULTS: Compared to the CD group, ED was reduced by 16% and 42% in the LD and FLD groups, respectively (p < 0.05). Qualitative analysis showed no significant difference among the 3 groups (p > 0.05), while quantitative analysis revealed significantly higher attenuation in the LD and FLD groups. Signal-to-noise ratios and CNRs of the LD and FLD groups were significantly higher except for the CNR at the left circumflex branch of the FLD group (p < 0.05). CONCLUSION: Increasing iodine concentration and noise level may further reduce the radiation dose by 26% on top of a 16% reduction from 100 kV to 80 kV without image quality compromise.
RCT Entities:
RATIONALE AND OBJECTIVES: To test whether higher iodine concentration together with higher noise level could lead to a further dose reduction in an already low dose coronary CT angiography (CCTA) protocol without comprising image quality. MATERIALS AND METHODS: One hundred eighty patients with suspected coronary artery disease (CAD) were randomly assigned into three groups: (a) conventional dose (CD) group, 100 kV with a noise index (NI) of 25 and iohexol (350 mg I/ml); (b) low dose (LD) group, 80 kV with a NI of 25 and iohexol (350 mg I/ml); (c) further low dose (FLD) group, 80 kV with a NI of 30 and iomeprol (400 mg I/ml). The volume and injection rate of contrast medium were fixed at 60 ml and 5 ml/s. The radiation dose (volume CT dose index [CTDIvol], dose length product [DLP], and effective dose [ED]) were recorded. For image quality, both quantitative (enhancement, noise, signal-to-noise ratio [SNR], and contrast-to-noise ratio [CNR]) and qualitative indices were assessed. RESULTS: Compared to the CD group, ED was reduced by 16% and 42% in the LD and FLD groups, respectively (p < 0.05). Qualitative analysis showed no significant difference among the 3 groups (p > 0.05), while quantitative analysis revealed significantly higher attenuation in the LD and FLD groups. Signal-to-noise ratios and CNRs of the LD and FLD groups were significantly higher except for the CNR at the left circumflex branch of the FLD group (p < 0.05). CONCLUSION: Increasing iodine concentration and noise level may further reduce the radiation dose by 26% on top of a 16% reduction from 100 kV to 80 kV without image quality compromise.