Japanese Journal of Radiology

, Volume 28, Issue 6, pp 437–445 | Cite as

Coronary computed tomography angiography using prospective electrocardiography-gated axial scans with 64-detector computed tomography: evaluation of stair-step artifacts and padding time

  • Fumiko KimuraEmail author
  • Tatsuo Umezawa
  • Tomonari Asano
  • Ruri Chihara
  • Naoko Nishi
  • Shigeyoshi Nishimura
  • Fumikazu Sakai
Original Article



We compared stair-step artifacts and radiation dose between prospective electrocardiography (ECG)-gated coronary computed tomography angiography (prospective CCTA) and retrospective CCTA using 64-detector CT and determined the optimal padding time (PT) for prospective CCTA.

Materials and methods

We retrospectively evaluated 183 patients [mean heart rate (HR) <65 beats/min, maximum HR instability <5 beats/min] who had undergone CCTA. We scored stair-step artifacts from 1 (severe) to 5 (none) and evaluated the effective dose in 53 patients with retrospective CCTA and 130 with prospective CCTA (PT 200 ms, n = 32; PT 50 ms, n = 98).


Mean artifact scores were 4.3 in both retrospective and prospective CCTAs. However, statistically more arteries scored <3 (nonassessable) on prospective CCTA (P < 0.001). Mean scores for prospective CCTA with 200- and 50-ms PT were 4.1 and 4.3, respectively (no significant difference). The radiation dose of prospective CCTA was reduced by 59.1% to 80.7%.


Prospective CCTA reduces the radiation dose and allows diagnostic imaging in most cases but shows more nonevaluable artifacts than retrospective CCTA. Use of 50-ms instead of 200-ms PT appears to maintain image quality in patients with a mean HR < 65 beats/min and HR instability of <5 beats/min.

Key words

Coronary CT angiography Artifact Radiation dose 


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Copyright information

© Japan Radiological Society 2010

Authors and Affiliations

  • Fumiko Kimura
    • 1
    Email author
  • Tatsuo Umezawa
    • 1
  • Tomonari Asano
    • 1
  • Ruri Chihara
    • 2
  • Naoko Nishi
    • 1
  • Shigeyoshi Nishimura
    • 2
  • Fumikazu Sakai
    • 1
  1. 1.Department of Diagnostic RadiologySaitama Medical University International Medical CenterHidakaJapan
  2. 2.Department of CardiologySaitama Medical University International Medical CenterHidakaJapan

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