title: Contrast material and radiation dose reduction strategy for triple-rule-out cardiac CT angiography: feasibility study of non-ECG-gated low kVp scan of the whole chest following coronary CT angiography.
abstract: BACKGROUND
  Dedicated coronary computed tomography (CT) scan has been proven to be an accurate diagnostic modality in evaluating coronary artery disease. A second phase scan starting immediately after the coronary CT scan might enable visualization of the different vascular territories of the entire chest.
  
  
  OBJECTIVE
  To investigate the feasibility of a contrast material and radiation dose reduction triple-rule-out (TRO) CT angiography (CTA) protocol with serial non-ECG-gated low kVp scan of the whole chest, which utilizes a recirculated contrast agent.
  
  
  METHODS
  Thirty patients were scanned with the new TRO-CTA protocol; after the coronary scan with retrospective ECG-gating, non-ECG-gated whole-chest CTA was performed at 80 kVp to evaluate aortic arch (AAr) and pulmonary trunk (PT). Another 30 patients were scanned by our conventional TRO-CTA protocol at 120 kVp with retrospective ECG-gating. We compared the estimated effective dose (ED), contrast material (CM) dose, contrast-to-noise ratio (CNR) of the ascending aorta (AAo), and the rate of patients who could achieve adequate attenuation of the AAr and PT between the two protocols.
  
  
  RESULTS
  The total ED of the new TRO-CTA protocol was 29.6% lower than that of the conventional protocol (P < 0.01). The amount of CM used for the new TRO-CTA protocol was significantly lower than in the conventional protocol (60.1 ± 9.6 mL vs. 91.8 ± 22.6 mL, P < 0.01). The CNR of the AAo was 30.2% higher with the new TRO-CTA protocol than with the conventional protocol (P < 0.01). There was no significant difference in the success rate of adequate attenuation of the AAr and PT between the two protocols (P > 0.05).
  
  
  CONCLUSIONS
  The new TRO-CTA protocol can reduce the total dose of radiation and the contrast dose and yield adequate vascular enhancement compared with the conventional protocol.
authors: Diagnostic Radiology, Amakusa Medical Center, Kumamoto, Japan Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan masafkidoh@yahoo.co.jp.
authors: Masafumi
authors: M
authors: Kidoh
authors: Diagnostic Radiology, Amakusa Medical Center, Kumamoto, Japan Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan.
authors: Takeshi
authors: T
authors: Nakaura
authors: Diagnostic Radiology, Amakusa Medical Center, Kumamoto, Japan Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan.
authors: Shinichi
authors: S
authors: Nakamura
authors: Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan.
authors: Tomohiro
authors: T
authors: Namimoto
authors: Department of Cardiology, Amakusa Medical Center, Kumamoto, Japan.
authors: Toshimitsu
authors: T
authors: Nozaki
authors: Department of Cardiology, Amakusa Medical Center, Kumamoto, Japan.
authors: Naritsugu
authors: N
authors: Sakaino
authors: Department of Surgery, Amakusa Medical Center, Kumamoto, Japan.
authors: Kazunori
authors: K
authors: Harada
authors: Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan.
authors: Yasuyuki
authors: Y
authors: Yamashita
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D055424:Cardiac-Gated Imaging Techniques / Q000379:methods*; D003287:Contrast Media; D017023:Coronary Angiography / Q000379:methods*; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging*; D004562:Electrocardiography / Q000379:methods; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007479:Iopamidol; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011651:Pulmonary Artery / Q000000981:diagnostic imaging; D011829:Radiation Dosage; D013902:Radiography, Thoracic / Q000379:methods; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D007479:Iopamidol
keywords: Triple-rule-out CT angiography; contrast dose; low tube voltage; radiation dose