title: Coronary MR angiography at 3T: fat suppression versus water-fat separation.
abstract: OBJECTIVE
  To compare Dixon water-fat suppression with spectral pre-saturation with inversion recovery (SPIR) at 3T for coronary magnetic resonance angiography (MRA) and to demonstrate the feasibility of fat suppressed coronary MRA at 3T without administration of a contrast agent.
  
  
  METHODS
  Coronary MRA with Dixon water-fat separation or with SPIR fat suppression was compared on a 3T scanner equipped with a 32-channel cardiac receiver coil. Eight healthy volunteers were examined. Contrast-to-noise ratio (CNR), signal-to-noise ratio (SNR), right coronary artery (RCA), and left anterior descending (LAD) coronary artery sharpness and length were measured and statistically compared. Two experienced cardiologists graded the visual image quality of reformatted Dixon and SPIR images (1: poor quality to 5: excellent quality).
  
  
  RESULTS
  Coronary MRA images in healthy volunteers showed improved contrast with the Dixon technique compared to SPIR (CNR blood-fat: Dixon = 14.9 ± 2.9 and SPIR = 13.9 ± 2.1; p = 0.08, CNR blood-myocardium: Dixon = 10.2 ± 2.7 and SPIR = 9.11 ± 2.6; p = 0.1). The Dixon method led to similar fat suppression (fat SNR with Dixon: 2.1 ± 0.5 vs. SPIR: 2.4 ± 1.2, p = 0.3), but resulted in significantly increased SNR of blood (blood SNR with Dixon: 19.9 ± 4.5 vs. SPIR: 15.5 ± 3.1, p < 0.05). This means the residual fat signal is slightly lower with the Dixon compared to the SIPR technique (although not significant), while the SNR of blood is significantly higher with the Dixon technique. Vessel sharpness of the RCA was similar for Dixon and SPIR (57 ± 7 % vs. 56 ± 9 %, p = 0.2), while the RCA visualized vessel length was increased compared to SPIR fat suppression (107 ± 21 vs. 101 ± 21 mm, p < 0.001). For the LAD, vessel sharpness (50 ± 13 % vs. 50 ± 7 %, p = 0.4) and vessel length (92 ± 46 vs. 90 ± 47 mm, p = 0.4) were similar with both techniques. Consequently, the Dixon technique resulted in an improved visual score of the coronary arteries in the water fat separated images of healthy subjects (RCA: 4.6 ± 0.5 vs. 4.1 ± 0.7, p = 0.01, LAD: 4.1 ± 0.7 vs. 3.5 ± 0.8, p = 0.007).
  
  
  CONCLUSIONS
  Dixon water-fat separation can significantly improve coronary artery image quality without the use of a contrast agent at 3T.
authors.affiliation: Division of Imaging Sciences and Biomedical Engineering, King's College London, London, UK. maryam.nezafat@kcl.ac.uk.|Department of Medicine, Beth Israel Deaconess Medical Centre and Harvard Medical School, Boston, MA, USA. maryam.nezafat@kcl.ac.uk.
authors.forename: Maryam
authors.initials: M
authors.lastname: Nezafat
authors.affiliation: Division of Imaging Sciences and Biomedical Engineering, King's College London, London, UK.
authors.forename: Markus
authors.initials: M
authors.lastname: Henningsson
authors.affiliation: Multidisciplinary Cardiovascular Research Centre and the Division of Cardiovascular and Diabetes Research, Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK.
authors.forename: David P
authors.initials: DP
authors.lastname: Ripley
authors.affiliation: Division of Imaging Sciences and Biomedical Engineering, King's College London, London, UK.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Dedieu
authors.affiliation: Division of Imaging Sciences and Biomedical Engineering, King's College London, London, UK.
authors.forename: Gerald
authors.initials: G
authors.lastname: Greil
authors.affiliation: Multidisciplinary Cardiovascular Research Centre and the Division of Cardiovascular and Diabetes Research, Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK.
authors.forename: John P
authors.initials: JP
authors.lastname: Greenwood
authors.affiliation: Philips Research, Hamburg, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Börnert
authors.affiliation: Multidisciplinary Cardiovascular Research Centre and the Division of Cardiovascular and Diabetes Research, Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK.
authors.forename: Sven
authors.initials: S
authors.lastname: Plein
authors.affiliation: Division of Imaging Sciences and Biomedical Engineering, King's College London, London, UK.|Pontificia Universidad Católica de Chile, Escuela de Ingeniería, Santiago, Chile.
authors.forename: René M
authors.initials: RM
authors.lastname: Botnar
mesh_terms: D000273:Adipose Tissue / Q000000981:diagnostic imaging*; D000328:Adult; D003287:Contrast Media / Q000737:chemistry; D017023:Coronary Angiography; D003331:Coronary Vessels / Q000000981:diagnostic imaging*; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D018810:Magnetic Resonance Angiography; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D059629:Signal-To-Noise Ratio; D014867:Water
chemical_list: D003287:Contrast Media; D014867:Water
keywords: Coronary magnetic resonance angiography; Dixon; SPIR; Vessel length; Vessel sharpness