title: Transient ischemic dilatation ratio derived from myocardial perfusion scintigraphy: What are we looking at?
abstract: BACKGROUND
  Elevated transient ischemic dilatation (TID) ratio during myocardial perfusion imaging (MPI) is described as a marker of severe CAD, even in acquisitions with normal perfusion. This was initiated to explore the effects of stressor type on the TID. Additionally the relation between the TID and other functional parameters, such as end diastolic volume (EDV), end systolic volume (ESV), and left ventricle ejection fraction (LVEF), heart rate (HR), and severity of ischemia, was evaluated.
  
  
  METHODS
  A total of 299 consecutive patients referred for a 2-day stress/rest MPI protocol were included. Patients were stressed with either adenosine (n = 164) or exercise (n = 135). MPI data were analyzed with an automated software tool to determine TID, EDV, ESV, LVEF, SSS, and SDS. The SDS was used to quantify the degree of ischemia, with a SDS > or = 3 considered ischemic.
  
  
  RESULTS
  Comparison of the adenosine and exercise stressed population revealed significant differences, especially in parameters derived from the poststress acquisition. Within the exercise stressed population, TID was proportional with the SDS (R(2) = .12); whereas the adenosine population did not show such a relation (R(2) = .001). Difference in HR between rest and poststress acquisitions showed high levels of linear regression with TID values of both the adenosine (R(2) = .41) and exercise (R(2) = .29) stressed population.
  
  
  CONCLUSIONS
  In an exercise stressed population, TID is determined by both the degree of ischemia and the heart-rate difference between the two acquisition moments. TID within the adenosine population was found to be highly proportional with the HR, rather than with the degree of ischemia.
authors.affiliation: Division of Nuclear Medicine, Leiden University Medical Center, P.O. Box 9600, 2300 RC, Leiden, The Netherlands.
authors.forename: B J
authors.initials: BJ
authors.lastname: van der Veen
authors.forename: N
authors.initials: N
authors.lastname: Kuperij
authors.forename: M P M
authors.initials: MP
authors.lastname: Stokkel
mesh_terms: D000241:Adenosine / Q000378:metabolism; D000368:Aged; D001331:Automation; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging; D015444:Exercise; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging*; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia; D009943:Organophosphorus Compounds / Q000737:chemistry; D015609:Organotechnetium Compounds / Q000737:chemistry; D010477:Perfusion; D011877:Radionuclide Imaging / Q000379:methods*; D012189:Retrospective Studies; D016277:Ventricular Function, Left
chemical_list: D009943:Organophosphorus Compounds; D015609:Organotechnetium Compounds; C078700:technetium tc-99m tetrofosmin; D000241:Adenosine