title: Consideration of perfusion reserve in viability assessment by myocardial Tl-201 rest-redistribution SPECT: a quantitative study with dual-isotope SPECT.
abstract: BACKGROUND
  To optimize the use of thallium 201 rest-redistribution study in Tl-201/technetium 99m sestamibi dual-isotope single photon emission computed tomography (SPECT), the predictability of Tl-201 rest-redistribution for viable myocardium was examined according to the degree of perfusion reserve.
  
  
  RESULTS
  Twenty patients with both unstable angina and left ventricular dysfunction were enrolled. Tl-201 rest-dipyridamole stress Tc-99m sestamibi gated SPECT/Tl-201 24-hour redistribution SPECT was performed before and 3 months after coronary artery bypass grafting. Through use of a 20-segment model, segmental stress perfusion, rest perfusion, and systolic thickening were quantified on gated SPECT by means of automatic quantitation software. Perfusion was expressed as the average percentage of maximal radioactivity uptake. To represent perfusion reserve, the perfusion difference score (PDS) was defined as rest perfusion minus stress perfusion. A low PDS indicated little or no inducible ischemia, and a high PDS indicated inducible ischemia. In dysfunctional myocardium, viability was defined by the improvement of thickening after coronary artery bypass grafting. The overall predictability of Tl-201 redistribution for viability was 0.709 of the area under the curve (AUC) in receiver operating characteristic analysis. With a cutoff of 7, predictability was significantly better in the low PDS group (AUC = 0.785) than in the high PDS group (AUC = 0.582).
  
  
  CONCLUSIONS
  The predictability of Tl-201 rest-redistribution for viability differs according to perfusion reserve. It was more reliable for dysfunctional myocardium with persistent perfusion decrease. On the basis of the continuum hypothesis of chronic stunning and hibernation, we suggest that dysfunctional myocardium with persistent perfusion decrease should be assessed by Tl-201 redistribution SPECT.
authors.affiliation: Department of Nuclear Medicine, Seoul National University College of Medicine, Yongun-dong, Seoul, Korea.
authors.forename: Jin Chul
authors.initials: JC
authors.lastname: Paeng
authors.forename: Dong Soo
authors.initials: DS
authors.lastname: Lee
authors.forename: Gi Jeong
authors.initials: GJ
authors.lastname: Cheon
authors.forename: Ki Bong
authors.initials: KB
authors.lastname: Kim
authors.forename: Jeong Seok
authors.initials: JS
authors.lastname: Yeo
authors.forename: June-Key
authors.initials: JK
authors.lastname: Chung
authors.forename: Myung Chul
authors.initials: MC
authors.lastname: Lee
mesh_terms: D000368:Aged; D000789:Angina, Unstable / Q000000981:diagnostic imaging; D019540:Area Under Curve; D001026:Coronary Artery Bypass / Q000009:adverse effects; D004176:Dipyridamole; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017682:Myocardial Stunning / Q000000981:diagnostic imaging* / Q000209:etiology / Q000503:physiopathology; D012680:Sensitivity and Specificity; D017256:Technetium Tc 99m Sestamibi; D013794:Thallium Radioisotopes; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging
chemical_list: D013794:Thallium Radioisotopes; D004176:Dipyridamole; D017256:Technetium Tc 99m Sestamibi