title: Body mass index-adapted prospective coronary computed tomography angiography. Determining the lowest limit for diagnostic purposes.
abstract: OBJECTIVE
  To investigate the value of 4 different protocols for prospectively triggered 256-slice coronary computed tomography angiography (coronary CTA).
  
  
  METHODS
  Two hundred and ten patients underwent prospectively triggered coronary CTA for suspected or known coronary artery disease (CAD). Patients with heart rate >75 bps before the scan despite ß-blocker administration and with arrhythmia were excluded. From January to September 2010, 60 patients underwent coronary CTA using a non-tailored protocol (120 kV; 200 mAs) and served as our 'control' group. From September 2010 to April 2012, based on the body mass index (BMI) of the examined patients (BMI subgroups of <25; 25-28; 28-30, and ≥ 30 kg/m(2)) current tube voltage and tube current were: (1) slightly, (2) moderately or (3) strongly reduced, resulting into the 3 following BMI-adapted acquisition groups: (1) a 'standard' (100/120 kV; 100-200 mAs; n=50), 2) a 'low dose' (100/120 kV; 75-150 mAs; n=50), and 3) an 'ultra-low dose' (100/120 kV; 50-100 mAs; n=50) protocol.
  
  
  RESULTS
  Patients examined using the non-tailored protocol exhibited the highest radiation exposure (3.2 ± 0.4 mSv), followed by the standard (1.6 ± 0.7 mSv), low-dose (1.2 ± 0.6 mSv) and ultra-low dose protocol (0.7 ± 0.3 mSv) (radiation savings of 50%, 63% and 78% respectively). Overall image quality was similar with standard dose (1.9 ± 0.6) and low-dose (2.0 ± 0.5) compared to the non-tailored group (1.9 ± 0.5) (p=NS for all). In the ultra-low dose group however, image quality was significant reduced (2.7 ± 0.6), p<0.05 versus all other groups).
  
  
  CONCLUSIONS
  Using BMI-adapted low dose acquisitions image quality can be maintained with simultaneous radiation savings of ∼65% (dose of ∼1 mSv). This appears to be the lower limit for diagnostic coronary CTA, whereas ultra-low dose acquisitions result in significant image degradation.
authors: University of Heidelberg, Department of Diagnostic and Interventional Radiology, Heidelberg, Germany. waldemar.hosch@med.uni-heidelberg.de
authors: Waldemar
authors: W
authors: Hosch
authors: Nina P
authors: NP
authors: Hofmann
authors: Dirk
authors: D
authors: Mueller
authors: Johannes
authors: J
authors: Iwan
authors: Gitsios
authors: G
authors: Gitsioudis
authors: Stefan
authors: S
authors: Siebert
authors: Evangelos
authors: E
authors: Giannitsis
authors: Hans U
authors: HU
authors: Kauczor
authors: Hugo A
authors: HA
authors: Katus
authors: Grigorios
authors: G
authors: Korosoglou
mesh_terms: D000465:Algorithms; D001822:Body Burden; D015992:Body Mass Index; D017023:Coronary Angiography / Q000379:methods* / Q000706:statistics & numerical data; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging* / Q000453:epidemiology; D005260:Female; D005858:Germany / Q000453:epidemiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011829:Radiation Dosage; D011835:Radiation Protection / Q000379:methods* / Q000706:statistics & numerical data; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity