title: Rapid detection of myocardial infarction by subsecond, free-breathing delayed contrast-enhancement cardiovascular magnetic resonance.
abstract: BACKGROUND
  An ultrafast, delayed contrast-enhancement cardiovascular magnetic resonance technique that can acquire subsecond, "snapshot" images during free breathing (subsecond) is becoming widely available. This technique provides myocardial infarction (MI) imaging with complete left ventricular coverage in < 30 seconds. However, the accuracy of this technique is unknown.
  
  
  RESULTS
  We prospectively compared subsecond imaging with routine breath-hold delayed contrast-enhancement cardiovascular magnetic resonance (standard) in consecutive patients. Two cohorts with unambiguous standards of truth were prespecified: (1) patients with documented prior MI (n=135) and (2) patients without MI and with low likelihood of coronary disease (lowest Framingham risk category; n=103). Scans were scored masked to identity and clinical information. Sensitivity, specificity, and accuracy of subsecond imaging for MI diagnosis were 87%, 96%, and 91%, respectively. Compared with the standard technique (98%, 100%, 99%), the subsecond technique had modestly reduced sensitivity (P=0.0001), but specificity was excellent. Missed infarcts were generally small or subendocardial (87%). Overall, regional transmural extent of infarction scores were highly concordant (2083/2294; 91%); however, 51 of 337 regions (15%) considered predominantly infarcted (> 50% transmural extent of infarction) by the standard technique were considered viable (< or = 25% transmural extent of infarction) by the subsecond technique. Quantitative analysis demonstrated moderately reduced contrast-to-noise ratios for subsecond imaging between infarct and remote myocardium (12.0+/-7.2 versus 20.1+/-6.6; P<0.0001) and infarct and left ventricular cavity (-2.5+/-2.7 versus 3.6+/-3.7; P<0.0001).
  
  
  CONCLUSIONS
  MI can be rapidly detected by subsecond delayed contrast-enhancement cardiovascular magnetic resonance during free breathing with high accuracy. This technique could be considered the preferred approach in patients who are more acutely ill or unable to hold their breath. However, compared with standard imaging, sensitivity is mildly reduced, and the transmural extent of infarction may be underestimated.
authors.affiliation: Duke Cardiovascular Magnetic Resonance Center, Durham, NC 27710, USA.
authors.forename: Burkhard
authors.initials: B
authors.lastname: Sievers
authors.forename: Michael D
authors.initials: MD
authors.lastname: Elliott
authors.forename: Lynne M
authors.initials: LM
authors.lastname: Hurwitz
authors.forename: Timothy S E
authors.initials: TS
authors.lastname: Albert
authors.forename: Igor
authors.initials: I
authors.lastname: Klem
authors.forename: Wolfgang G
authors.initials: WG
authors.lastname: Rehwald
authors.forename: Michele A
authors.initials: MA
authors.lastname: Parker
authors.forename: Robert M
authors.initials: RM
authors.lastname: Judd
authors.forename: Raymond J
authors.initials: RJ
authors.lastname: Kim
mesh_terms: D000328:Adult; D000368:Aged; D015331:Cohort Studies; D003287:Contrast Media; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000000981:diagnostic imaging; D011446:Prospective Studies; D011859:Radiography; D012119:Respiration; D015656:Respiratory Mechanics / Q000502:physiology; D013997:Time Factors
chemical_list: D003287:Contrast Media