title: Estimation of coronary flow reserve with the use of dynamic planar and SPECT images of Tc-99m tetrofosmin.
abstract: BACKGROUND
  We developed a noninvasive method to examine coronary flow reserve with technetium 99m tetrofosmin based on the microsphere model. According to the microsphere model, myocardial blood flow (MBF) can be calculated by MBF = q / integral C(t)dt, where q is myocardial activity and C(t) is tracer concentration in blood. Because the ratio of integral C(t)dt at stress to rest is equal to the ratio of the first transit count in the pulmonary artery (PA) and attenuation factors were canceled out, we calculated the increase ratio of MBF (MBF(IR)).
  
  
  RESULTS
  After injection of dipyridamole, tetrofosmin was injected as a bolus and serial dynamic planar images were obtained to measure the first transit count in PA (PAC). Myocardial single photon emission computed tomography was performed to measure the regional myocardial count (RMC). MBF(IR) was calculated as [(RMCs x PACr)/(RMCr x PACs) - 1] x 100, where r and s denote resting and stress conditions, respectively. In contrast, the increase in the myocardial uptake ratio (MUR(IR)) was defined as (RMCs x SCr/RMCr x SCs - 1) x 100, where SC is syringe count of tracer. The results were as follows: (1) The mean MBF of healthy subjects was 46.9% +/- 22.8%. (2) MBF(IR) of the infarcted region and ischemic region was significantly decreased (8.3% +/- 12.2% and 11.2% +/- 11.9%, respectively; P <.001). (3) MUR(IR) was significantly lower than MBF(IR) (14.1% +/- 21.2%; P <.001). (4) MBF(IR) decreased according to the heart rate at rest (r = 0.47; P <.05).
  
  
  CONCLUSIONS
  MBF(IR) is a potential parameter with which to evaluate coronary flow reserve when the changes of arterial input function during stress are considered.
authors.affiliation: Department of Internal Medicine, Takashima General Hospital, Shiga, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Sugihara
authors.forename: Y
authors.initials: Y
authors.lastname: Yonekura
authors.forename: K
authors.initials: K
authors.lastname: Kataoka
authors.forename: D
authors.initials: D
authors.lastname: Fukai
authors.forename: N
authors.initials: N
authors.lastname: Kitamura
authors.forename: Y
authors.initials: Y
authors.lastname: Taniguchi
mesh_terms: D003326:Coronary Circulation; D006321:Heart / Q000000981:diagnostic imaging*; D006801:Humans; D009943:Organophosphorus Compounds; D015609:Organotechnetium Compounds; D015899:Tomography, Emission-Computed, Single-Photon
chemical_list: D009943:Organophosphorus Compounds; D015609:Organotechnetium Compounds; C078700:technetium tc-99m tetrofosmin