title: Intracoronary versus intravenous injection of 99mTc-tetrofosmin: comparison of myocardial perfusion patterns and wall motion.
abstract: OBJECTIVE
  The accuracy of viability and defect size detection by Tc-tetrofosmin has been discussed by several authors. The lower myocardial extraction fraction of the latter compared with Tc-sestamibi or Tl has often been emphasized. We hypothesized that the intracoronary (i.c.) injection of tracer activity, i.e. higher than that theoretically achievable in the case of intravenous (i.v.) administration, could demonstrate the clinical relevance of this finding intra-individually. In this study, myocardial perfusion images obtained after tracer injection down the infarct-related artery were compared with i.v. injection images in the same patients. The trial also provided us with the opportunity to compare the wall motion values calculated using conventional Tc-tetrofosmin gated single-photon emission computed tomography (SPECT) studies with those obtained using optimal target/background ratios after i.c. injection.
  
  
  METHODS
  Fourteen patients with acute myocardial infarction, no history of previous cardiac events, single vessel disease and no visible collaterals in the coronary arteriogram were included in the study. Electrocardiogram gated SPECT was carried out separately after i.c. and i.v. injections of the tracer within 5-7 days following thrombolytic therapy. Myocardial perfusion patterns were compared by contingency table analysis after semi-quantitative visual scoring. Segmental wall motion was compared using quantified polar map data in a subset of patients (eight of 14) with normal to moderately hypoperfused myocardium supplied by the left coronary artery.
  
  
  RESULTS
  Visual perfusion scores of both studies showed good concordance (kappa, 0.70), with complete agreement in 94 of 119 segments. Nearly all of the discordant segments (24 of 25) were mildly better scored in i.c. studies than in i.v. studies. The mean wall motion values calculated on polar maps of 78 segments for i.c. and i.v. studies were 8.4 +/- 1.2 mm and 8.2 +/- 1.3 mm (mean Delta wall motion=0.23 mm), respectively. High segmental wall motion correlation was observed (R=0.90; P<0.0001).
  
  
  CONCLUSIONS
  It can be concluded that infarct-related myocardial perfusion scores obtained after i.c. and i.v. injections of Tc-tetrofosmin compare favourably, with a total agreement rate of 79%. However, the additional information obtained in 21% of the total number of myocardial segments by i.c. injection may indicate a mild underestimation of myocardial viability by i.v. injection. Conventional gated SPECT using i.v. Tc-tetrofosmin was demonstrated to be a reliable technique in the detection of true wall motion.
authors.affiliation: Department of Nuclear Medicine, Ondokuz Mayis University, Medical School, 55139 Samsun, Turkey. tarik@tarikbasoglu.com
authors.forename: Tarik
authors.initials: T
authors.lastname: Basoglu
authors.forename: Fevziye
authors.initials: F
authors.lastname: Canbaz
authors.forename: Mahmut
authors.initials: M
authors.lastname: Sahin
authors.forename: Mehmet
authors.initials: M
authors.lastname: Elcik
authors.forename: Banu
authors.initials: B
authors.lastname: Kirtiloglu
authors.forename: Murathan
authors.initials: M
authors.lastname: Sahin
authors.forename: Oktay
authors.initials: O
authors.lastname: Yapici
mesh_terms: D001158:Arteries / Q000000981:diagnostic imaging*; D003331:Coronary Vessels / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007269:Injections, Intra-Arterial; D007275:Injections, Intravenous; D008297:Male; D008875:Middle Aged; D009068:Movement; D009203:Myocardial Infarction / Q000150:complications / Q000000981:diagnostic imaging*; D009943:Organophosphorus Compounds / Q000008:administration & dosage*; D015609:Organotechnetium Compounds / Q000008:administration & dosage*; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000008:administration & dosage; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging* / Q000209:etiology
chemical_list: D009943:Organophosphorus Compounds; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; C078700:technetium tc-99m tetrofosmin