title: Closing in on the K edge: coronary CT angiography at 100, 80, and 70 kV-initial comparison of a second- versus a third-generation dual-source CT system.
abstract: OBJECTIVE
  To prospectively evaluate radiation and contrast medium requirements for performing high-pitch coronary computed tomographic (CT) angiography at 70 kV using a third-generation dual-source CT system in comparison to a second-generation dual-source CT system.
  
  
  METHODS
  All patients gave informed consent for this institutional review board-approved study. Forty-five patients (median age, 52 years; 27 men) were imaged in high-pitch mode with a third-generation dual-source CT system at 70 kV (n = 15) or with a second-generation dual-source CT system at 80 or 100 kV (n = 15 for each). Tube voltage was based on body mass index: 80 or 70 kV for less than 26 kg/m(2) versus 100 kV for 26-30 kg/m(2). For the 80- and 100-kV protocols, 80 mL of contrast material was injected, versus 45 mL for the 70-kV protocol. Data were reconstructed by using a second-generation iterative reconstruction algorithm for second-generation dual-source CT and a recently introduced third-generation iterative reconstruction algorithm for third-generation dual-source CT. Objective image quality was measured for various regions of interest, and subjective image quality was evaluated with a five-point Likert scale.
  
  
  RESULTS
  The signal-to-noise ratio of the coronary CT angiography studies acquired with 70 kV was significantly higher (70 kV: 14.3-17.6 vs 80 kV: 7.1-12.9 vs 100 kV: 9.8-12.9; P < .0497) than those acquired with the other two protocols for all coronary arteries. Qualitative image quality analyses revealed no significant differences between the three CT angiography protocols (median score, 5; P > .05). The mean effective dose was 75% and 108% higher (0.92 mSv ± 0.3 [standard deviation] and 0.78 mSv ± 0.2 vs 0.44 mSv ± 0.1; P < .0001), respectively, for the 80- and 100-kV CT angiography protocols than for the 70-kV CT angiography protocol.
  
  
  CONCLUSIONS
  In nonobese patients, third-generation high-pitch coronary dual-source CT angiography at 70 kV results in robust image quality for studying the coronary arteries, at significantly reduced radiation dose (0.44 mSv) and contrast medium volume (45 mL), thus enabling substantial radiation dose and contrast medium savings as compared with second-generation dual-source CT.
authors.affiliation: From the Institute of Clinical Radiology and Nuclear Medicine (M.M., H.H., S.S., S.O.S., T.H.) and 1st Department of Medicine (R.L., M.B.), University Medical Center Mannheim, Medical Faculty Mannheim-Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany; Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC (U.J.S.); Center for Medical Imaging-North East Netherlands, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands (R.V.); and Imaging and Therapy Division, Siemens Healthcare, Forchheim, Germany (C.L., T.A.).
authors.forename: Mathias
authors.initials: M
authors.lastname: Meyer
authors.forename: Holger
authors.initials: H
authors.lastname: Haubenreisser
authors.forename: U Joseph
authors.initials: UJ
authors.lastname: Schoepf
authors.forename: Rozemarijn
authors.initials: R
authors.lastname: Vliegenthart
authors.forename: Christianne
authors.initials: C
authors.lastname: Leidecker
authors.forename: Thomas
authors.initials: T
authors.lastname: Allmendinger
authors.forename: Ralf
authors.initials: R
authors.lastname: Lehmann
authors.forename: Sonja
authors.initials: S
authors.lastname: Sudarski
authors.forename: Martin
authors.initials: M
authors.lastname: Borggrefe
authors.forename: Stefan O
authors.initials: SO
authors.lastname: Schoenberg
authors.forename: Thomas
authors.initials: T
authors.lastname: Henzler
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D055424:Cardiac-Gated Imaging Techniques; D003287:Contrast Media; D017023:Coronary Angiography / Q000295:instrumentation / Q000379:methods*; D003327:Coronary Disease / Q000000981:diagnostic imaging*; D004562:Electrocardiography; D005260:Female; D006801:Humans; D007479:Iopamidol / Q000031:analogs & derivatives; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods*
chemical_list: D003287:Contrast Media; C057937:iomeprol; D007479:Iopamidol