title: Susceptibility-sensitive magnetic resonance imaging detects human myocardium supplied by a stenotic coronary artery without a contrast agent.
abstract: OBJECTIVE
  Evaluation of the severity of a coronary artery stenosis is of paramount importance for therapy. A relevant stenosis provokes post-stenotic microvascular dilation with capillary recruitment. This autoregulatory response was investigated in the present study by use of susceptibility-sensitive magnetic resonance imaging (MRI) without contrast agents.
  
  
  BACKGROUND
  Functional alterations of the microvascular system may be studied noninvasively and without a contrast agent by susceptibility-sensitive MRI, which is based on the paramagnetic property of deoxyhemoglobin. This effect, also referred to as the "blood oxygenation level-dependent (BOLD) effect," is investigated by phase relaxation (T(2)*) measurements.
  
  
  METHODS
  In patients (n = 16) with single-vessel coronary artery disease, no history of myocardial infarction, normal left ventricular function at rest, and a positive stress echocardiogram, the susceptibility-sensitive parameter T(2)* was assessed in the myocardium.
  
  
  RESULTS
  In regions associated with the stenotic artery, T(2)* was significantly lower than in residual myocardium (p < 0.01). This difference in T(2)* increased after application of the vasodilator dipyridamole (p < 0.001). In patients being re-investigated after therapeutic interventions, the microvascular dilation was partly removed.
  
  
  CONCLUSIONS
  For the first time, we could show that myocardial BOLD MRI detects post-stenotic capillary recruitment dependent on coronary artery stenosis.
authors.affiliation: Medical Clinic, University of Wuerzburg, Wuerzburg, Germany.
authors.forename: Christian M
authors.initials: CM
authors.lastname: Wacker
authors.forename: Andreas W
authors.initials: AW
authors.lastname: Hartlep
authors.forename: Stefan
authors.initials: S
authors.lastname: Pfleger
authors.forename: Lothar R
authors.initials: LR
authors.lastname: Schad
authors.forename: Georg
authors.initials: G
authors.lastname: Ertl
authors.forename: Wolfgang R
authors.initials: WR
authors.lastname: Bauer
mesh_terms: D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D003287:Contrast Media; D017023:Coronary Angiography; D003326:Coronary Circulation / Q000502:physiology*; D023921:Coronary Stenosis / Q000175:diagnosis* / Q000503:physiopathology; D004452:Echocardiography / Q000379:methods; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000473:pathology*; D011379:Prognosis; D012016:Reference Values; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D014654:Vascular Patency
chemical_list: D003287:Contrast Media