title: Cerebral bone subtraction CT angiography using 80 kVp and sinogram-affirmed iterative reconstruction: contrast medium and radiation dose reduction with improvement of image quality.
abstract: BACKGROUND
  The purpose of this study was to evaluate the feasibility of a contrast medium (CM), radiation dose reduction protocol for cerebral bone-subtraction CT angiography (BSCTA) using 80-kVp and sinogram-affirmed iterative reconstruction (SAFIRE).
  
  
  METHODS
  Seventy-five patients who had undergone BSCTA under the 120- (n = 37) or the 80-kVp protocol (n = 38) were included. CM was 370 mgI/kg for the 120-kVp and 296 mgI/kg for the 80-kVp protocol; the 120- and the 80-kVp images were reconstructed with filtered back-projection (FBP) and SAFIRE, respectively. We compared effective dose (ED), CT attenuation, image noise, and contrast-to-noise ratio (CNR) of two protocols. We also scored arterial contrast, sharpness, depiction of small arteries, visibility near skull base/clip, and overall image quality on a four-point scale.
  
  
  RESULTS
  ED was 62% lower at 80- than 120-kVp (0.59 ± 0.06 vs 1.56 ± 0.13 mSv, p < 0.01). CT attenuation of the internal carotid artery (ICA) and middle cerebral artery (MCA) was significantly higher on 80- than 120-kVp (ICA: 557.4 ± 105.7 vs 370.0 ± 59.3 Hounsfield units (HU), p < 0.01; MCA: 551.9 ± 107.9 vs 364.6 ± 62.2 HU, p < 0.01). The CNR was also significantly higher on 80- than 120-kVp (ICA: 46.2 ± 10.2 vs 36.9 ± 7.6, p < 0.01; MCA: 45.7 ± 10.0 vs 35.7 ± 9.0, p < 0.01). Visibility near skull base and clip was not significantly different (p = 0.45). The other subjective scores were higher with the 80- than the 120-kVp protocol (p < 0.05).
  
  
  CONCLUSIONS
  The 80-kVp acquisition with SAFIRE yields better image quality for BSCTA and substantial reduction in the radiation and CM dose compared to the 120-kVp with FBP protocol.
authors.affiliation: Department of Radiology, Kumamoto City Hospital, Kumamoto, Japan. y.nagayama1980@gmail.com.|Department of Diagnostic Radiology, Kumamoto University, 1-1-1, Honjo, Chuo-ku, Kumamoto, 860-8556, Japan. y.nagayama1980@gmail.com.
authors.forename: Yasunori
authors.identifier: http://orcid.org/0000-0003-3280-7346
authors.initials: Y
authors.lastname: Nagayama
authors.affiliation: Department of Diagnostic Radiology, Kumamoto University, 1-1-1, Honjo, Chuo-ku, Kumamoto, 860-8556, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Nakaura
authors.affiliation: Department of Radiology, Kumamoto City Hospital, Kumamoto, Japan.
authors.forename: Akinori
authors.initials: A
authors.lastname: Tsuji
authors.affiliation: Department of Radiology, Kumamoto City Hospital, Kumamoto, Japan.
authors.forename: Joji
authors.initials: J
authors.lastname: Urata
authors.affiliation: Department of Radiology, Kumamoto City Hospital, Kumamoto, Japan.
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Furusawa
authors.affiliation: Department of Radiology, Kumamoto City Hospital, Kumamoto, Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Yuki
authors.affiliation: Department of Radiology, Kumamoto City Hospital, Kumamoto, Japan.
authors.forename: Kenichiro
authors.initials: K
authors.lastname: Hirarta
authors.affiliation: Department of Diagnostic Radiology, Kumamoto University, 1-1-1, Honjo, Chuo-ku, Kumamoto, 860-8556, Japan.
authors.forename: Seitaro
authors.initials: S
authors.lastname: Oda
authors.affiliation: Department of Diagnostic Radiology, Kumamoto University, 1-1-1, Honjo, Chuo-ku, Kumamoto, 860-8556, Japan.
authors.forename: Masafumi
authors.initials: M
authors.lastname: Kidoh
authors.affiliation: Department of Diagnostic Radiology, Kumamoto University, 1-1-1, Honjo, Chuo-ku, Kumamoto, 860-8556, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Utsunomiya
authors.affiliation: Department of Diagnostic Radiology, Kumamoto University, 1-1-1, Honjo, Chuo-ku, Kumamoto, 860-8556, Japan.
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Yamashita
mesh_terms: D000368:Aged; D000072226:Computed Tomography Angiography / Q000379:methods*; D003287:Contrast Media; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D002532:Intracranial Aneurysm / Q000000981:diagnostic imaging*; D007479:Iopamidol; D008297:Male; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D012189:Retrospective Studies; D012886:Skull / Q000000981:diagnostic imaging*; D013382:Subtraction Technique
chemical_list: D003287:Contrast Media; D007479:Iopamidol
keywords: Angiography; Computed tomography; Image processing; Intracranial aneurysm; Radiation protection