title: Quantitative ischemia detection during cardiac magnetic resonance stress testing by use of FastHARP.
abstract: BACKGROUND
  Because ECG alterations caused by ischemia cannot be reliably detected in the high-field MRI environment, detection of wall motion abnormalities is often used to ensure patient safety during stress testing. However, an experienced observer is needed to detect these abnormalities. In this study, we investigate the use of fast harmonic phase (FastHARP) MRI for the quantitative, operator-independent detection of the onset of ischemia during acute coronary occlusion.
  
  
  RESULTS
  Eight mongrel dogs underwent an acute 2-minute closed-chest coronary artery occlusion while continuous FastHARP images were acquired. Full regional wall strain was determined every other heartbeat in a single short-axis imaging slice. After 5 minutes of reperfusion, a second 2-minute ischemic episode was induced during the acquisition of conventional cine wall-motion images. The time at which ECG alterations were observed during the first ischemic period was recorded. The time from occlusion to the detection of ischemia, based on a consensus of 2 blinded observers, was determined for MRI. No significant ischemia was present in 2 animals. In the remaining animals, the onset of ischemia was detected significantly earlier by FastHARP than by cine MRI (9.5+/-5 versus 33+/-14 seconds, P<0.01). HARP ischemia detection preceded ECG changes, on average, by 54 seconds.
  
  
  CONCLUSIONS
  The rapid acquisition and detection of induced ischemia with FastHARP MRI shows promise as a nonsubjective method to diagnose significant coronary lesions during MR stress testing.
authors.affiliation: Johns Hopkins University, School of Medicine, Department of Radiology, MD 21287-0845, USA. dara@mri.jhu.edu
authors.forename: Dara L
authors.initials: DL
authors.lastname: Kraitchman
authors.forename: Smita
authors.initials: S
authors.lastname: Sampath
authors.forename: Ernesto
authors.initials: E
authors.lastname: Castillo
authors.forename: John A
authors.initials: JA
authors.lastname: Derbyshire
authors.forename: Raymond C
authors.initials: RC
authors.lastname: Boston
authors.forename: David A
authors.initials: DA
authors.lastname: Bluemke
authors.forename: Bernhard L
authors.initials: BL
authors.lastname: Gerber
authors.forename: Jerry L
authors.initials: JL
authors.lastname: Prince
authors.forename: Nael F
authors.initials: NF
authors.lastname: Osman
mesh_terms: D000818:Animals; D003326:Coronary Circulation; D003327:Coronary Disease / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology; D004195:Disease Models, Animal; D018450:Disease Progression; D004285:Dogs; D004562:Electrocardiography; D005080:Exercise Test / Q000009:adverse effects; D005583:Fourier Analysis; D006339:Heart Rate; D008279:Magnetic Resonance Imaging / Q000379:methods*; D019028:Magnetic Resonance Imaging, Cine; D008863:Microspheres; D009200:Myocardial Contraction; D017202:Myocardial Ischemia / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D015425:Myocardial Reperfusion; D009206:Myocardium / Q000473:pathology; D011237:Predictive Value of Tests; D013997:Time Factors