title: Acute myocardial infarction: susceptibility-weighted cardiac MRI for the detection of reperfusion haemorrhage at 1.5 T.
abstract: OBJECTIVE
  To assess whether susceptibility-weighted imaging (SWI) provides better image contrast for the detection of haemorrhagic ischaemia-reperfusion injury in the heart.
  
  
  METHODS
  Thirty patients (all men; mean age 53 years) underwent cardiac magnetic resonance imaging (MRI) within 7 days of primary percutaneous intervention for acute ST elevation myocardial infarction (STEMI). Multiple gradient-echo T2* sequences with magnitude and phase reconstructions were acquired. A high-pass filtered phase map was used to create a mask for the SWI reconstructions. The difference in image contrast was assessed in those patients with microvascular obstruction. A mixed effects regression model was used to test the effect of echo time and reconstruction method on phase and contrast-to-noise ratio (CNR). Medians and interquartile ranges (IQR) are reported.
  
  
  RESULTS
  T2* in haemorrhagic infarcts was shorter than in non-haemorrhagic infarcts (33.5 ms [24.9-43] versus 49.9 ms [44.6-67.6]; p=0.0007). The effect of echo time on phase was significant (p<0.0001), as was the effect of haemorrhage on phase (p=0.0016). SWI reconstruction had a significant effect on the CNR at all echo times (echoes 1-5, p<0.0001; echo 6, p=0.01; echo 7, p=0.02). The median echo number at which haemorrhage was first visible was less for SWI compared to source images (echo 2 versus echo 5, p=0.0002).
  
  
  CONCLUSIONS
  Cardiac SWI improves the contrast between myocardial haemorrhage and the surrounding tissue following STEMI and has potential as a new tool for identifying patients with ischaemia-reperfusion injury.
authors.affiliation: Robert Steiner MRI Unit, MRC Clinical Sciences Centre, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London W12 0NN, UK.
authors.forename: G
authors.initials: G
authors.lastname: Durighel
authors.affiliation: Robert Steiner MRI Unit, MRC Clinical Sciences Centre, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London W12 0NN, UK.
authors.forename: P F
authors.initials: PF
authors.lastname: Tokarczuk
authors.affiliation: Department of Physics, Budapest University of Technology and Economics, Budapest, Hungary.
authors.forename: A
authors.initials: A
authors.lastname: Karsa
authors.affiliation: Statistical Advisory Service, School of Public Health, Imperial College, London W12 1PG, UK.
authors.forename: F
authors.initials: F
authors.lastname: Gordon
authors.affiliation: Robert Steiner MRI Unit, MRC Clinical Sciences Centre, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London W12 0NN, UK; Department of Cardiology, Imperial College Healthcare NHS Trust, London, UK; Hammersmith Hospital, Du Cane Road, London W12 0HS, UK; Department of Cardiology, National Heart Centre Singapore, 17 Third Hospital Ave, Singapore 168752, Singapore; Duke-NUS Graduate Medical School, 8 College Road, 169857, Singapore.
authors.forename: S A
authors.initials: SA
authors.lastname: Cook
authors.affiliation: Robert Steiner MRI Unit, MRC Clinical Sciences Centre, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London W12 0NN, UK. Electronic address: declan.oregan@imperial.ac.uk.
authors.forename: D P
authors.initials: DP
authors.lastname: O'Regan
mesh_terms: D055424:Cardiac-Gated Imaging Techniques / Q000379:methods*; D003287:Contrast Media; D052203:Ferrosoferric Oxide; D019786:Gadolinium DTPA; D006470:Hemorrhage / Q000175:diagnosis* / Q000209:etiology*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000628:therapy*; D015425:Myocardial Reperfusion / Q000009:adverse effects*; D062645:Percutaneous Coronary Intervention; D019047:Phantoms, Imaging; D011446:Prospective Studies
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA; D052203:Ferrosoferric Oxide