title: Value of vasodilator stress myocardial contrast echocardiography and magnetic resonance imaging for the differential diagnosis of ischemic versus nonischemic cardiomyopathy.
abstract: OBJECTIVE
  Noninvasive differentiation of ischemic versus nonischemic cardiomyopathy (CM) remains challenging because of the low specificity of imaging-based tests in these patients. We hypothesized that myocardial contrast echocardiography (MCE) and cardiac magnetic resonance (CMR), combined with vasodilator stress, could provide accurate alternatives for determining the cause of CM.
  
  
  METHODS
  To allow side-by-side comparisons between these techniques with coronary angiography as a reference, we studied 16 patients referred for coronary angiography after abnormal nuclear perfusion studies. Both MCE and CMR images were acquired within 48 hours with infusion of adenosine. MCE included flash-echo imaging during intravenous infusion of echocardiographic contrast solution. CMR included gadolinium injections for first-pass perfusion and delayed enhancement imaging. MCE and CMR images were reviewed by experienced investigators, blinded to the findings of the other modality and angiography. For each technique, each myocardial segment was classified as normal or abnormal. Sensitivity and specificity of each technique were calculated against the angiography reference. These calculations were also performed using a perfusion territory as a unit of analysis.
  
  
  RESULTS
  Six of 16 patients had normal coronary arteries, and three patients had stenosis < 50%. By using this threshold for abnormal perfusion, segment-by-segment comparisons with angiography resulted in sensitivity of 0.88, 0.61, and 0.71 and specificity of 0.74, 0.86, and 0.94 for CMR perfusion, delayed enhancement scans, and MCE sequences, respectively. Using stenosis > 70% as a threshold resulted in a small decrease in both sensitivity and specificity (0.02-0.04) for all three techniques. Analysis of the ability of these techniques to detect an abnormality in at least one perfusion territory yielded sensitivity of 1.00, 1.00, and 0.86 and specificity of 0.78, 0.78, and 0.89, correspondingly, which were threshold-independent.
  
  
  CONCLUSIONS
  Both CMR and MCE perfusion imaging may be used to differentiate between ischemic and nonischemic CM. These emerging diagnostic tools may prove useful in strategizing treatment in these patients and thus avoiding unnecessary invasive procedures.
authors.affiliation: University of Chicago, Chicago, Illinois 60637, USA. vmoravi@medicine.bsd.uchicago.edu
authors.forename: Victor
authors.initials: V
authors.lastname: Mor-Avi
authors.forename: Rick
authors.initials: R
authors.lastname: Koch
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Holper
authors.forename: Sascha
authors.initials: S
authors.lastname: Goonewardena
authors.forename: Patrick D
authors.initials: PD
authors.lastname: Coon
authors.forename: James K
authors.initials: JK
authors.lastname: Min
authors.forename: Savitri
authors.initials: S
authors.lastname: Fedson
authors.forename: R Parker
authors.initials: RP
authors.lastname: Ward
authors.forename: Roberto M
authors.initials: RM
authors.lastname: Lang
mesh_terms: D009202:Cardiomyopathies / Q000175:diagnosis* / Q000209:etiology*; D003287:Contrast Media; D003937:Diagnosis, Differential; D004452:Echocardiography / Q000379:methods*; D005080:Exercise Test / Q000379:methods; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000150:complications* / Q000175:diagnosis*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014665:Vasodilator Agents
chemical_list: D003287:Contrast Media; D014665:Vasodilator Agents; D019786:Gadolinium DTPA