title: Low-dose dobutamine tissue-tagged magnetic resonance imaging with 3-dimensional strain analysis allows assessment of myocardial viability in patients with ischemic cardiomyopathy.
abstract: BACKGROUND
  Tissue-tagged magnetic resonance imaging (MRI) with 3-dimensional (3D) myocardial strain analysis allows quantitative assessment of myocardial contractility. We assessed the hypothesis that 3D strain determination at rest and with low-dose dobutamine would discriminate between viable and nonviable myocardium in patients with ischemic cardiomyopathy (ICM).
  
  
  RESULTS
  MRI with radiofrequency tissue-tagging at rest and with low-dose dobutamine was performed in 16 normal volunteers and 14 patients with ICM. Three-dimensional global and regional circumferential strains (Ecc) were computed for all subjects at rest and with dobutamine. Results were compared with clinically indicated conventional viability studies. Compared with normal volunteers, global left ventricular Ecc was significantly decreased in patients with ICM at rest (-0.15+/-0.06 versus -0.27+/-0.03; P<0.001) and with dobutamine (-0.17+/-0.08 versus -0.37+/-0.10; P<0.001). Ecc was significantly decreased in nonviable regions compared with viable segments at rest (-0.08+/-0.06 versus -0.17+/-0.10; P<0.001) and with dobutamine (-0.07+/-0.06 versus -0.21+/-0.11; P<0.001). Ecc in viable segments increased significantly in response to dobutamine (P=0.04), whereas Ecc did not change in nonviable segments (P=0.50). Normal controls (96 segments) had increased Ecc at rest (-0.27+/-0.07) and with dobutamine (-0.37+/-0.15) compared with both viable and nonviable regions in ICM patients (P<0.001).
  
  
  CONCLUSIONS
  Noninvasive dobutamine tissue-tagged MRI with calculation of 3D strain allows the identification, quantification and display of regionally varying ventricular function. The response of systolic strain to low-dose dobutamine has significant promise in discriminating between viable and nonviable myocardium.
authors.affiliation: Department of Cardiovascular Medicine, Washington University, St. Louis, MO, USA.
authors.forename: Douglas
authors.initials: D
authors.lastname: Bree
authors.forename: Jason R
authors.initials: JR
authors.lastname: Wollmuth
authors.forename: Brian P
authors.initials: BP
authors.lastname: Cupps
authors.forename: Marc D
authors.initials: MD
authors.lastname: Krock
authors.forename: Analyn
authors.initials: A
authors.lastname: Howells
authors.forename: Joseph
authors.initials: J
authors.lastname: Rogers
authors.forename: Nader
authors.initials: N
authors.lastname: Moazami
authors.forename: Michael K
authors.initials: MK
authors.lastname: Pasque
mesh_terms: D000368:Aged; D001696:Biomechanical Phenomena; D002316:Cardiotonic Agents / Q000008:administration & dosage; D002470:Cell Survival; D003187:Compliance; D001026:Coronary Artery Bypass; D004280:Dobutamine / Q000008:administration & dosage; D005260:Female; D006352:Heart Ventricles / Q000473:pathology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction; D017202:Myocardial Ischemia / Q000473:pathology* / Q000503:physiopathology; D009206:Myocardium / Q000473:pathology*; D011300:Preoperative Care; D016037:Single-Blind Method; D013314:Stress, Mechanical
chemical_list: D002316:Cardiotonic Agents; D004280:Dobutamine