title: The effects of early and late scanning on image quality and functional parameters in myocardial perfusion imaging.
abstract: METHODS
  Timing of acquisition is a factor that may influence the subdiaphragmatic activity in myocardial perfusion scintigraphy (MPS). According to the instructions of tetrofosmin, scintigraphy may already be started 15 minutes postinjection. The aim of the present study was to compare the image quality and the functional parameters between early and late scanning. Eventually, 49 consecutive patients underwent a 2-day MPS protocol in which 15 and 45 minutes after the injection of 500 MBq of technetium-99m-tetrofosmin scintigraphy both at stress and rest were performed. The amount of subdiaphragmatic tracer activity was scored from "no tracer activity" to "severe." Moderate and severe subdiaphragmatic tracer activity was considered relevant for the interpretation of the myocardial perfusion scan.
  
  
  RESULTS
  Two-thirds of the patients (64%) showed a considerable amount of subdiaphragmatic activity on the 15 minutes rest images, whereas only 9 patients (18%) had considerable subdiaphragmatic activity on the late images. Stress imaging showed comparable results, however, subdiaphragmatic activity was generally less frequent and less prominent following stress. The value of the ejection fraction was significantly lower during early imaging comparing with late imaging. Lower ejection fraction was exclusively noticed in imaging with moderate and severe subdiaphragmatic tracer activity related wrong border estimation.
  
  
  CONCLUSIONS
  Acquisition 15 minutes after the injection of Tetrofosmin shows a significant and clinically relevant subdiaphragmatic activity in most myocardial perfusion scans leading to poorer image quality and to an erroneous measurement of the ejection fraction. Therefore, early acquisition in MPS is not recommended in clinical practice.
authors.affiliation: Department of Nuclear Medicine, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Ibrahim
authors.initials: I
authors.lastname: Albutaihi
authors.forename: Linda
authors.initials: L
authors.lastname: van der Veen
authors.forename: Arthur
authors.initials: A
authors.lastname: Scholte
authors.forename: Marcel P
authors.initials: MP
authors.lastname: Stokkel
mesh_terms: D003964:Diaphragm / Q000378:metabolism; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D007267:Injections; D055414:Myocardial Perfusion Imaging / Q000379:methods*; D009943:Organophosphorus Compounds / Q000008:administration & dosage / Q000378:metabolism; D015609:Organotechnetium Compounds / Q000008:administration & dosage / Q000378:metabolism; D011786:Quality Control; D012189:Retrospective Studies; D013997:Time Factors
chemical_list: D009943:Organophosphorus Compounds; D015609:Organotechnetium Compounds; C078700:technetium tc-99m tetrofosmin