title: Effect of reduced x-ray tube voltage, low iodine concentration contrast medium, and sinogram-affirmed iterative reconstruction on image quality and radiation dose at coronary CT angiography: results of the prospective multicenter REALISE trial.
abstract: BACKGROUND
  Both low tube voltage and sinogram-affirmed iterative reconstruction (IR) techniques hold promise to decrease radiation dose at coronary CT angiography (CCTA). The increased iodine contrast at low tube voltage allows for minimizing iodine load.
  
  
  OBJECTIVE
  To assess the effect of reduced x-ray tube voltage, low iodine concentration contrast medium and IR on image quality and radiation dose at CCTA.
  
  
  METHODS
  Two hundred thirty-one consecutive patients with suspected coronary artery disease were enrolled in this prospective, multicenter trial and randomized to 1 of 2 dual-source CCTA protocols: 120-kVp with 370 mgI/mL iopromide or iopamidol (n = 116; 44 women; 55.3 ± 9.8 years) or 100 kVp with 270 mgI/mL iodixanol (n = 115; 48 women; 54.2 ± 10.4 years). Reconstruction was performed with filtered back projection and IR. Attenuation, image noise, signal-to-noise ratio, and contrast-to-noise ratio were measured and image quality scored. Size-specific dose estimates and effective doses were calculated.
  
  
  RESULTS
  There were no significant differences in mean arterial attenuation (406.6 ± 76.7 vs 409.7 ± 65.2 Hounsfield units; P = .739), image noise (18.7 ± 3.8 vs 17.9 ± 3.4 Hounsfield units; P = .138), signal-to-noise ratio (22.5 ± 5.4 vs 23.7 ± 6.1; P = .126), contrast-to-noise ratio (17.5 ± 5.5 vs 18.3 ± 6.1; P = .286), or image quality scores (4.1 ± 0.9 vs 4.0 ± 0.9; P > .05) between 120-kVp filtered back projection-reconstructed and 100-kVp IR-reconstructed series. Mean iodine dose was 26.5% lower (18.3 ± 0.5 vs 24.9 ± 0.9 g; P < .0001), mean size-specific dose estimate was 35.1% lower (17.9 ± 6.6 vs 27.5 ± 8.2 mGy; P < .0001), and effective dose was 34.9% lower (2.3 ± 1.0 vs 3.5 ± 1.1 mSv; P < .0001) with the 100 kVp compared with the 120-kVp protocol, respectively.
  
  
  CONCLUSIONS
  Using low x-ray tube voltage and IR allows for decreasing the iodine load and effective radiation dose at CCTA while maintaining image quality.
authors.affiliation: Department of Radiology, State Key Laboratory of Cardiovascular Disease, Fu Wai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, #167 Bei-Li-Shi Street, Xi-Cheng District, Beijing 100037, People's Republic of China.
authors.forename: Wei-Hua
authors.initials: WH
authors.lastname: Yin
authors.affiliation: Department of Radiology, State Key Laboratory of Cardiovascular Disease, Fu Wai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, #167 Bei-Li-Shi Street, Xi-Cheng District, Beijing 100037, People's Republic of China. Electronic address: blu@vip.sina.com.
authors.forename: Bin
authors.initials: B
authors.lastname: Lu
authors.affiliation: Department of Radiology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China.
authors.forename: Jian-Bo
authors.initials: JB
authors.lastname: Gao
authors.affiliation: Department of Radiology, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning, China.
authors.forename: Pei-Ling
authors.initials: PL
authors.lastname: Li
authors.affiliation: Department of Radiology, Baotou Central Hospital, Baotou, Inner Mongolia, China.
authors.forename: Kai
authors.initials: K
authors.lastname: Sun
authors.affiliation: Department of Radiology, Shanxi DAYI Hospital, Taiyuan, Shanxi, China.
authors.forename: Zhi-Feng
authors.initials: ZF
authors.lastname: Wu
authors.affiliation: Department of Radiology, Rui Jin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
authors.forename: Wen-Jie
authors.initials: WJ
authors.lastname: Yang
authors.affiliation: Department of Radiology, Inner Mongolia People's Hospital, Huhehaote, Inner Mongolia, China.
authors.forename: Xiao-Qin
authors.initials: XQ
authors.lastname: Zhang
authors.affiliation: Department of Radiology, Xijing Hospital, Fourth Military Medical University. Xi'an, Shaanxi, China.
authors.forename: Min-Wen
authors.initials: MW
authors.lastname: Zheng
authors.affiliation: Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, USA.
authors.forename: Andrew D
authors.initials: AD
authors.lastname: McQuiston
authors.affiliation: Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, USA.
authors.forename: Felix G
authors.initials: FG
authors.lastname: Meinel
authors.affiliation: Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, USA; Division of Cardiology, Department of Medicine, Medical University of South Carolina, Charleston, SC, USA.
authors.forename: Uwe Joseph
authors.initials: UJ
authors.lastname: Schoepf
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002681:China; D003287:Contrast Media / Q000008:administration & dosage*; D017023:Coronary Angiography / Q000379:methods*; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007472:Iohexol / Q000008:administration & dosage / Q000031:analogs & derivatives*; D007479:Iopamidol / Q000008:administration & dosage*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D059629:Signal-To-Noise Ratio; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D007472:Iohexol; C038192:iopromide; D007479:Iopamidol
keywords: Contrast agent; Coronary CT angiography; Imaging optimization; Iterative reconstruction; Radiation exposure