title: Optimized subtraction coronary CT angiography protocol for clinical use with short breath-holding time-initial experience.
abstract: OBJECTIVE
  Subtraction coronary computed tomography (CT) angiography (CCTA), which enables the removal of calcium and coronary stents from CCTA images, has been clinically introduced on a second-generation 320-row CT scanner. However, this technique for clinical use is not optimized. The long breath-holding time for two data acquisitions, which causes image misregistration and patient's discomfort, may limit the clinical availability of this subtraction technique.
  
  
  METHODS
  This study received approval from the institutional review board; prior informed consent to participate was obtained from all patients. We performed subtraction CCTA of five patients using the test injection method and optimized the interval time between the first (pulmonary-arterial phase) and the second (coronary-arterial phase) scans to achieve robust subtraction. The patients' breath-holding times were recorded. We compared breath-holding times between our new protocol and previous study's protocol (estimated).
  
  
  RESULTS
  Mean breath-holding time in our new protocol was 18.3 ± 3.4 seconds and that in previous protocol was 29.8 ± 3.6 seconds (difference in mean breath-holding time was 11.5 seconds). Misregistration artifacts were not shown in final subtraction CCTA images. These images improved luminal visualization in the calcified lesion.
  
  
  CONCLUSIONS
  Our test injection protocol can shorten the breath-holding time, which is helpful for successful subtraction CCTA imaging, potentially resulting in an increase of subtraction CCTA examinations in many institutions.
authors.affiliation: Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, 1-1-1, Honjo, Kumamoto 860-8556, Japan. Electronic address: masafkidoh@yahoo.co.jp.
authors.forename: Masafumi
authors.initials: M
authors.lastname: Kidoh
authors.affiliation: Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, 1-1-1, Honjo, Kumamoto 860-8556, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Utsunomiya
authors.affiliation: Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, 1-1-1, Honjo, Kumamoto 860-8556, Japan.
authors.forename: Seitaro
authors.initials: S
authors.lastname: Oda
authors.affiliation: Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, 1-1-1, Honjo, Kumamoto 860-8556, Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Yuki
authors.affiliation: Department of Medical Physics, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Funama
authors.affiliation: Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, 1-1-1, Honjo, Kumamoto 860-8556, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Namimoto
authors.affiliation: Department of Cardiovascular Medicine, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan.
authors.forename: Megumi
authors.initials: M
authors.lastname: Yamamuro
authors.affiliation: Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, 1-1-1, Honjo, Kumamoto 860-8556, Japan.
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Yamashita
mesh_terms: D000368:Aged; D015901:Angiography, Digital Subtraction / Q000379:methods*; D062485:Breath Holding; D017023:Coronary Angiography / Q000379:methods*; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008297:Male; D011856:Radiographic Image Enhancement / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013382:Subtraction Technique; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: Computed tomography; contrast media; coronary CT angiography; diagnosis