title: Cardiac MRI in patients with cardiac pacemakers: practical methods for reducing susceptibility artifacts and optimizing image quality.
abstract: BACKGROUND
  Magnetic resonance imaging (MRI) of pacemaker patients has become available despite of previous contraindications. However, pacing systems containing ferromagnetic material may hamper the diagnostic quality of cardiac MR (CMR) images.
  
  
  OBJECTIVE
  To study methods for reducing susceptibility-based artifacts in CMR examinations of pacemaker patients.
  
  
  METHODS
  Altogether 16 patients were scanned with 1.5T MRI scanner using cine balanced steady-state free-precession (bSSFP) and spoiled gradient echo (SPGR) sequences. The use of frequency-scout was also evaluated. For myocardial late gadolinium-enhanced (LGE) imaging, SPGR or bSSFP readout inversion-recovery prepared gradient echo sequences were used with and without phase-sensitive inversion-recovery (PSIR). Two radiologists subjectively compared the image quality (IQ) and the ranges of susceptibility artifacts were evaluated objectively.
  
  
  RESULTS
  The IQ proved adequate for diagnosing each patient, although in a few patients with a left-side implanted generator, artifacts hampered IQ in the anterior and anteroseptal segments of the myocardium in bSSFP cine and LGE sequences. In bSSFP cine, the use of frequency-scout could often transfer the banding artifacts away from the left ventricular myocardium. In LGE imaging, the artifacts were more pronounced in IR-bSSFP and PSIR than in IR-SPGR sequences. The ranges of generator-based artifacts were greater in bSSFP (10-12 cm) than in SPGR (6 cm) sequences due to banding artifacts.
  
  
  CONCLUSIONS
  The artifacts caused by pacemakers typically did not compromise the diagnostic IQ. The use of frequency-scout prior to bSSFP cine or the use of SPGR-based sequences could also improve IQ.
authors.affiliation: HUS Medical Imaging Center, Radiology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland Department of Physics, University of Helsinki, Helsinki, Finland touko.kaasalainen@hus.fi.
authors.forename: Touko
authors.initials: T
authors.lastname: Kaasalainen
authors.affiliation: HUS Medical Imaging Center, Radiology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.
authors.forename: Sari
authors.initials: S
authors.lastname: Kivistö
authors.affiliation: HUS Medical Imaging Center, Radiology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.
authors.forename: Miia
authors.initials: M
authors.lastname: Holmström
authors.affiliation: HUS Medical Imaging Center, Radiology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland Department of Biomedical Engineering and Computational Science, School of Science, Aalto University, Helsinki, Finland.
authors.forename: Juha
authors.initials: J
authors.lastname: Peltonen
authors.affiliation: Heart and Lung Center, Division of Cardiology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.
authors.forename: Sami
authors.initials: S
authors.lastname: Pakarinen
authors.affiliation: Heart and Lung Center, Division of Cardiology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.
authors.forename: Helena
authors.initials: H
authors.lastname: Hänninen
authors.affiliation: HUS Medical Imaging Center, Radiology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.
authors.forename: Outi
authors.initials: O
authors.lastname: Sipilä
mesh_terms: D000328:Adult; D016477:Artifacts; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging; D008297:Male; D009206:Myocardium / Q000473:pathology; D015588:Observer Variation; D010138:Pacemaker, Artificial; D015203:Reproducibility of Results
keywords: CMR; frequency-scout; image quality; pacemaker; susceptibility artifact