title: Image quality in reduced-dose coronary CT angiography.
abstract: OBJECTIVE
  Concerns for patient's risk of radiation-induced cancer have increased demand for reduced-dose coronary computed tomography angiography (CCTA). Previous comparisons of full and reduced-dose CCTA were not conclusive, because results were compared in different groups of patients. Presented here are results in patients examined by a widely used full dose CCTA protocol and a new low-dose alternative.
  
  
  METHODS
  Standard full-dose and low-dose CCTA with tube voltages of 120/100 kV were applied on 70 patients with intermediate probability of coronary artery disease (CAD). Both protocols used prospective electrocardiogram-gated acquisition on a 320-detector row CT scanner, whereas at low-dose CCTA the phase window was increased from 10% to 75% of R-R interval.
  
  
  RESULTS
  Despite a mean dose reduction of 80%, from 4.9 ± 0.98 to 0.98 ± 0.24 mSv, visual image quality was not significantly affected at the low-dose protocol. Contrast level, image noise, and CNR for both protocols were similar in the majority of coronary segments. CNR for standard and low-dose protocol were 23.7 ± 17.1 and 23.2 ± 26.8, P = NS. Correlation between visual image quality and heart rate variability was strong at low dose: r = -0.58, P = .01, and absent at full dose: r = -0.07, P = .77.
  
  
  CONCLUSIONS
  Image quality of blood vasculature is generally not affected by 80% CCTA dose reduction applied to standard prospective electrocardiogram-gated acquisition. The performance at the low-dose protocol owes to the increased phase window, enhancing image quality at the cost of sensitivity to heart rate variability as compared with standard CCTA.
authors.affiliation: First Moscow State Medical University, Department of Radiology, Moscow, Russia. ninagagarina@rambler.ru
authors.forename: Nina V
authors.initials: NV
authors.lastname: Gagarina
authors.forename: Roy
authors.initials: R
authors.lastname: Irwan
authors.forename: Galina
authors.initials: G
authors.lastname: Gordina
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Fominykh
authors.forename: Paul E
authors.initials: PE
authors.lastname: Sijens
mesh_terms: D000328:Adult; D000368:Aged; D055424:Cardiac-Gated Imaging Techniques / Q000379:methods; D017023:Coronary Angiography / Q000379:methods*; D003327:Coronary Disease / Q000000981:diagnostic imaging*; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted; D014057:Tomography, X-Ray Computed / Q000379:methods*