title: Combined rest redistribution thallium-201 SPECT and low-dose dobutamine contractility assessment in a simple and practical new viability protocol.
abstract: OBJECTIVE
  Rest-redistribution (RR) thallium-201 (Tl-201) imaging is commonly used for myocardial viability evaluation. Contractile reserve (CR) assessment with low-dose dobutamine (LDD) is another method that highly predicts functional recovery following revascularization. In this study, we investigate the feasibility of a new protocol that provides combined Tl-201 uptake, resting and CR functional regional myocardial information in a single examination.
  
  
  METHODS
  A total of 41 patients underwent RR-gated-SPECT Tl-201 myocardial perfusion imaging. The LDD infusion was maintained during delayed imaging. Segmental Tl-201 uptake was classified into normal, fixed decrease (mild to absent) and reversible, and sub-classified by wall motion (WM)/thickening (WT) changes between early resting and delayed LDD gated images into normal, fixed or improved dysfunctional (CR present) segments.
  
  
  RESULTS
  Out of 820 examined segments, 33 showed no appreciable Tl-201 uptake to evaluate WM/WT. In a dysfunctional myocardium, CR was significantly higher (P < 0.001) in reversible and fixed than in normal Tl-201 segments. The CR in dysfunctional segments with fixed decrease Tl-201 uptake was significantly higher (P < 0.05) in mild and moderate than in severe fixed defects. Both fixed Tl-201 defects and lack of CR were observed more (P < 0.05) in akinetic/dyskinetic than in hypokinetic segments.
  
  
  CONCLUSIONS
  Simultaneous assessment of myocardial viability by RR Tl-201 uptake, resting and CR functional regional information is feasible and can be easily attained using this new protocol. Moreover, this protocol requires no additional time or radioactivity when compared with the usual RR Tl-201 protocol. Validation of this protocol with patients' revascularization data is needed.
authors.affiliation: Nuclear Medicine Division, Mount Sinai Medical Center, Mount Sinai School of Medicine, One Gustave L. Levy Place, Box 1141, New York, NY 10029-6574, USA. sherif.heiba@mssm.edu
authors.forename: Sherif I
authors.initials: SI
authors.lastname: Heiba
authors.forename: Gennie
authors.initials: G
authors.lastname: Yee
authors.forename: Hussein M
authors.initials: HM
authors.lastname: Abdel-Dayem
authors.forename: Irini
authors.initials: I
authors.lastname: Youssef
authors.forename: John
authors.initials: J
authors.lastname: Coppola
mesh_terms: D002316:Cardiotonic Agents; D004280:Dobutamine; D005080:Exercise Test; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications / Q000000981:diagnostic imaging*; D015203:Reproducibility of Results; D012146:Rest; D012680:Sensitivity and Specificity; D013794:Thallium Radioisotopes; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*; D018487:Ventricular Dysfunction, Left / Q000150:complications / Q000000981:diagnostic imaging*
chemical_list: D002316:Cardiotonic Agents; D013794:Thallium Radioisotopes; D004280:Dobutamine