title: Is there an optimal respiratory reference position for self-navigated whole-heart coronary MR angiography?
abstract: OBJECTIVE
  To test the direct influence of the reference respiratory position on image quality for self-navigated whole-heart coronary MRI.
  
  
  METHODS
  Self-navigated whole-heart coronary MRI was performed in 11 healthy adult subjects. Respiratory motion was compensated for by using three different respiratory reference positions of the heart: end-inspiratory, end-expiratory, and the mean of the entire respiratory excursion. All datasets were reconstructed without motion compensation for comparison. Image quality was assessed in all reconstructions using signal-to-noise ratio (SNR) and contrst-to-noise ratio (CNR) measurements, as well as percentage vessel sharpness and visible length of the coronary arteries.
  
  
  RESULTS
  While SNR and CNR remained close to constant in all reconstructions, a clear and significant improvement in vessel sharpness was identified in all motion corrected datasets with respect to their uncorrected counterpart (e.g., percentage sharpness of the proximal right coronary artery (RCA): 61.6 ± 8.2% for end-inspiration, 64.1 ± 10.7% for end-expiration, and 63.3 ± 7.0% for the mean respiratory position versus 55.0 ± 10.4 for the uncorrected datasets; P < 0.05). Among all motion corrected reconstructions, the use of an end-expiratory reference position most consistently provided the highest image quality. In particular, some of the improvements in vessel sharpness and length measured for end-expiration were statistically significant with respect to the reconstructions performed at end-inspiration (e.g., percentage sharpness of the proximal left anterior descending coronary: 58.2 ± 7.4% versus 55.8 ± 8.4%; P < 0.05; and visible length of the RCA: 125.7 ± 25.9 mm versus 114.4 ± 27.4 mm; P < 0.05).
  
  
  CONCLUSIONS
  The use of end-expiration as a reference position for respiratory motion correction in free-breathing self-navigated whole heart coronary MRA significantly improves image quality. J
authors.affiliation: Advanced Clinical Imaging Technology, Siemens Healthcare, Lausanne, Switzerland.|Center for Biomedical Imaging (CIBM), Lausanne, Switzerland.|Department of Radiology, University Hospital (CHUV) and University of Lausanne (UNIL), Lausanne, Switzerland.
authors.forename: Davide
authors.initials: D
authors.lastname: Piccini
authors.affiliation: Center for Biomedical Imaging (CIBM), Lausanne, Switzerland.|Department of Radiology, University Hospital (CHUV) and University of Lausanne (UNIL), Lausanne, Switzerland.
authors.forename: Gabriele
authors.initials: G
authors.lastname: Bonanno
authors.affiliation: Center for Biomedical Imaging (CIBM), Lausanne, Switzerland.|Department of Radiology, University Hospital (CHUV) and University of Lausanne (UNIL), Lausanne, Switzerland.
authors.forename: Giulia
authors.initials: G
authors.lastname: Ginami
authors.affiliation: Healthcare Sector, Siemens AG, Erlangen, Germany.
authors.forename: Arne
authors.initials: A
authors.lastname: Littmann
authors.affiliation: Healthcare Sector, Siemens AG, Erlangen, Germany.
authors.forename: Michael O
authors.initials: MO
authors.lastname: Zenge
authors.affiliation: Center for Biomedical Imaging (CIBM), Lausanne, Switzerland.|Department of Radiology, University Hospital (CHUV) and University of Lausanne (UNIL), Lausanne, Switzerland.
authors.forename: Matthias
authors.initials: M
authors.lastname: Stuber
mesh_terms: D000328:Adult; D017023:Coronary Angiography / Q000379:methods*; D003331:Coronary Vessels / Q000502:physiology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D012016:Reference Values; D012119:Respiration; D059629:Signal-To-Noise Ratio
keywords: coronary MRA; free-breathing; reference position; respiratory motion; self-navigation