title: Determination of edema in porcine coronary arteries by T2 weighted cardiovascular magnetic resonance.
abstract: BACKGROUND
  Inflammation plays a pivotal role in all stages of atherosclerosis. Since edema is known to be an integral part of inflammation, a noninvasive technique that can identify edema in the coronary artery wall may provide unique information regarding plaque activity. In this study, we aimed to determine whether edema induced in porcine coronary arteries by balloon injury could be reliably detected by cardiovascular magnetic resonance (CMR) using a water sensitive T2-weighted short tau inversion recovery sequence (T2-STIR). We also aimed to compare these results to those of conventional T2-weighted (T2W) imaging.
  
  
  METHODS
  Edema was induced in the proximal left anterior descending (LAD) coronary artery wall in seven pigs by balloon injury. At baseline, and 1-10 days (average four) post injury, the proximal LAD was assessed by water sensitive T2-STIR and conventional T2W sequences in cross-sectional planes. CMR images were matched to histopathology, validated against Evans blue as a marker of increased vessel wall permeability, and correlated with the arterial amount of fibrinogen used as an edema surrogate marker.
  
  
  RESULTS
  Post injury, the T2-STIR images of the injured LAD vessel wall showed a significant 72%, relative signal intensity (SI) increase compared with baseline (p = 0.028). Using a threshold value of SI 7 SD above the average SI of the myocardium, T2-STIR detected edema in the vessel wall (i.e. enhancement) with a sensitivity of 100 and a specificity of 71. Twelve out of the 14 (86%) T2-STIR images displaying coronary artery wall enhancement also showed Evans blue uptake in the corresponding histology. The relative signal intensity showed a linear correlation with the amount of fibrinogen detected on the corresponding histopathology (ρ = 0.750, p = 0.05). The conventional T2W images did not show significant changes in SI post injury.
  
  
  CONCLUSIONS
  T2-STIR CMR enabled detection of coronary artery wall edema and could therefore be a non-invasive diagnostic tool for evaluation of inflammatory coronary artery wall activity.
authors.affiliation: Dept. of Cardiothoracic and Vascular Surgery T, Aarhus University Hospital Skejby, Brendstrupsgaardsvej 100, DK-8200 Aarhus N, Denmark. fjord@mr.au.dk
authors.forename: Steen Fjord
authors.initials: SF
authors.lastname: Pedersen
authors.forename: Samuel A
authors.initials: SA
authors.lastname: Thrysøe
authors.forename: William P
authors.initials: WP
authors.lastname: Paaske
authors.forename: Troels
authors.initials: T
authors.lastname: Thim
authors.forename: Erling
authors.initials: E
authors.lastname: Falk
authors.forename: Steffen
authors.initials: S
authors.lastname: Ringgaard
authors.forename: Won Yong
authors.initials: WY
authors.lastname: Kim
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D003324:Coronary Artery Disease / Q000175:diagnosis* / Q000209:etiology / Q000378:metabolism / Q000473:pathology; D003331:Coronary Vessels / Q000378:metabolism / Q000473:pathology*; D004195:Disease Models, Animal; D004489:Edema, Cardiac / Q000175:diagnosis* / Q000209:etiology / Q000378:metabolism / Q000473:pathology; D005260:Female; D005340:Fibrinogen / Q000378:metabolism; D007090:Image Interpretation, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods; D015588:Observer Variation; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D013552:Swine; D013997:Time Factors
chemical_list: D015415:Biomarkers; D005340:Fibrinogen