title: Optimizing contrast media application in coronary CT angiography at lower tube voltage: Evaluation in a circulation phantom and sixty patients.
abstract: OBJECTIVE
  The purpose was to investigate optimal contrast media (CM) injection parameters for lower kVp settings, whilst maintaining diagnostic attenuation levels.
  
  
  METHODS
  First, a circulation phantom with physiological parameters (BP 120/80mmHg, HR 60bpm) was used. A fixed CM injection protocol was used for each kVp setting (300mgI/ml [Iopromide], volume=45ml, flow rate=6.0ml/s, iodine delivery rate [IDR]=1.8gI/s, iodine load=13.5gI; at 120, 100, 80 and 70kVp). Then, IDR was decreased by steps of 0.2gI/s for each kVp setting, until diagnostically insufficient attenuation values were reached (<325HU). In order to keep injection time constant (7.5s), total iodine load (TIL) was reduced accordingly. Second, clinical applicability at 120 and 100kVp was evaluated in patients (n=60) referred for coronary CT angiography. A standard and reduced (12% less) CM protocol was used based on weight classes and scan duration ('high-pitch': 1s; 'adaptive sequence' and 'helical': 7s). Attenuation levels of the coronary arteries were measured and compared between protocols.
  
  
  RESULTS
  Using a fixed CM injection at each kVp level resulted in the following HU values: 335HU±31 (120kVp); 425HU±30 (100kVp); 587HU±29 (80kVp); 666HU±27 (70kVp). Keeping diagnostic enhancement levels (353HU±28) CM could be reduced as follows: 12% for 100kVp; 45% for 80kVp and 56% for 70kVp. Diagnostic enhancement levels could be reproduced with concurrent CM reduction (-12% at 100kV) in the clinical setting (382HU±35).
  
  
  CONCLUSIONS
  CM injection parameters can be substantially reduced at low kVp settings (up to 56% at 70kVp), whilst maintaining diagnostic attenuation levels. This may play an important role in CT imaging of the coronary arteries as well as cerebral and peripheral circulations in the future.
authors.affiliation: Department of Radiology, Maastricht University Medical Center, The Netherlands; CARIM, School for Cardiovascular Diseases, Maastricht University Medical Center, Maastricht, The Netherlands. Electronic address: madeleinekok1@gmail.com.
authors.forename: Madeleine
authors.initials: M
authors.lastname: Kok
authors.affiliation: Department of Radiology, Maastricht University Medical Center, The Netherlands; CARIM, School for Cardiovascular Diseases, Maastricht University Medical Center, Maastricht, The Netherlands. Electronic address: caspermihl@gmail.com.
authors.forename: Casper
authors.initials: C
authors.lastname: Mihl
authors.affiliation: Department of Radiology, Maastricht University Medical Center, The Netherlands. Electronic address: babs.hendriks@mumc.nl.
authors.forename: Babs M F
authors.initials: BM
authors.lastname: Hendriks
authors.affiliation: CARIM, School for Cardiovascular Diseases, Maastricht University Medical Center, Maastricht, The Netherlands; Department of Cardiology, Maastricht University Medical Center, The Netherlands. Electronic address: s.altintas@mumc.nl.
authors.forename: Sibel
authors.initials: S
authors.lastname: Altintas
authors.affiliation: Department of Radiology, Maastricht University Medical Center, The Netherlands; CARIM, School for Cardiovascular Diseases, Maastricht University Medical Center, Maastricht, The Netherlands; Department of Cardiology, Maastricht University Medical Center, The Netherlands. Electronic address: b.kietselaer@mumc.nl.
authors.forename: Bas L J H
authors.initials: BL
authors.lastname: Kietselaer
authors.affiliation: Department of Radiology, Maastricht University Medical Center, The Netherlands; CARIM, School for Cardiovascular Diseases, Maastricht University Medical Center, Maastricht, The Netherlands. Electronic address: j.wildberger@mumc.nl.
authors.forename: Joachim E
authors.initials: JE
authors.lastname: Wildberger
authors.affiliation: Department of Radiology, Maastricht University Medical Center, The Netherlands; CARIM, School for Cardiovascular Diseases, Maastricht University Medical Center, Maastricht, The Netherlands. Electronic address: m.das@mumc.nl.
authors.forename: Marco
authors.initials: M
authors.lastname: Das
mesh_terms: D000328:Adult; D000368:Aged; D001011:Aorta / Q000000981:diagnostic imaging; D001794:Blood Pressure / Q000502:physiology; D000072226:Computed Tomography Angiography / Q000379:methods*; D003287:Contrast Media / Q000008:administration & dosage*; D017023:Coronary Angiography / Q000379:methods*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D007083:Iliac Artery / Q000000981:diagnostic imaging; D007455:Iodine / Q000008:administration & dosage; D007472:Iohexol / Q000008:administration & dosage / Q000031:analogs & derivatives*; D008875:Middle Aged; D061330:Multidetector Computed Tomography / Q000379:methods; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D011856:Radiographic Image Enhancement / Q000379:methods; D012077:Renal Artery / Q000000981:diagnostic imaging; D036542:Tomography, Spiral Computed / Q000379:methods
chemical_list: D003287:Contrast Media; D007472:Iohexol; C038192:iopromide; D007455:Iodine
keywords: Contrast media; Multidetector-row computed tomography; Tube voltage