title: Twenty-four-hour Tl-201 delayed scan underestimates myocardial viability in patients with acute myocardial infarction after percutaneous transluminal coronary angioplasty.
abstract: BACKGROUND
  Myocardial viability in area at risk of acute myocardial infarction (AMI) after reperfusion therapy may be underestimated by the 24-hour images due to reverse redistribution (r-RD).
  
  
  METHODS
  Subjects were 37 AMI patients in whom Tc-99m pyrophosphate (PYP)/Tl-201 dual-isotope SPECT was positive. The 24-hour delayed scan was performed with only a Tl window. One month later, follow up rest Tl SPECT was performed to evaluate myocardial viability. In early (at PYP/Tl-201 dual-isotope SPECT), 24-hour, and one month follow up Tl studies, Tl uptake in the area of AMI was scored into four grades: 3 as normal to 0 as severely reduced. The scores were evaluated.
  
  
  RESULTS
  Among the 37 AMI lesions, there were 16 r-RD, 3 RD, 16 fixed defect (FD) and 2 normal (positive PYP and normal Tl). Mean Tl scores were early; 1.4 +/- 1.1, 24-hr; 0.9 +/- 0.9 and one month; 1.3 +/- 1.1. The 24-hour Tl score was lower than the early and one month Tl scores (p < 0.01).
  
  
  CONCLUSIONS
  Reverse redistribution is frequently observed in an area at risk where PYP SPECT was positive. Nuclear medicine physicians should be aware of the existence of frequent r-RD in Tl scan to avoid the underestimation of myocardial viability in the acute phase after PTCA.
authors.affiliation: Department of Radiology, Ehime University School of Medicine, Onsen-gun, Japan. tmochi@m.ehime-u.ac.jp
authors.forename: T
authors.initials: T
authors.lastname: Mochizuki
authors.forename: K
authors.initials: K
authors.lastname: Murase
authors.forename: Y
authors.initials: Y
authors.lastname: Sugawara
authors.forename: H
authors.initials: H
authors.lastname: Higashino
authors.forename: T
authors.initials: T
authors.lastname: Kikuchi
authors.forename: M
authors.initials: M
authors.lastname: Miyagawa
authors.forename: J
authors.initials: J
authors.lastname: Ikezoe
mesh_terms: D000368:Aged; D015906:Angioplasty, Balloon, Coronary; D005260:Female; D006801:Humans; D008297:Male; D009203:Myocardial Infarction / Q000000981:diagnostic imaging* / Q000628:therapy*; D015425:Myocardial Reperfusion; D019275:Radiopharmaceuticals; D016698:Technetium Tc 99m Pyrophosphate; D013794:Thallium Radioisotopes / Q000627:therapeutic use*; D013997:Time Factors; D015899:Tomography, Emission-Computed, Single-Photon
chemical_list: D019275:Radiopharmaceuticals; D013794:Thallium Radioisotopes; D016698:Technetium Tc 99m Pyrophosphate