title: Factors affecting the myocardial activity acquired during exercise SPECT with a high-sensitivity cardiac CZT camera as compared with conventional Anger camera.
abstract: OBJECTIVE
  Injected doses are difficult to optimize for exercise SPECT since they depend on the myocardial fraction of injected activity (MFI) that is detected by the camera. The aim of this study was to analyse the factors affecting MFI determined using a cardiac CZT camera as compared with those determined using conventional Anger cameras.
  
  
  METHODS
  Factors affecting MFI were determined and compared in patients who had consecutive exercise SPECT acquisitions with (201)Tl (84 patients) or (99m)Tc-sestamibi (87 patients) with an Anger or a CZT camera. A predictive model was validated in a group of patients routinely referred for (201)Tl (78 patients) or (99m)Tc-sestamibi (80 patients) exercise CZT SPECT.
  
  
  RESULTS
  The predictive model involved: (1) camera type, adjusted mean MFI being ninefold higher for CZT than for Anger SPECT, (2) tracer type, adjusted mean MFI being twofold higher for (201)Tl than for (99m)Tc-sestamibi, and (3) logarithm of body weight. The CZT SPECT model led to a +1 ± 26% error in the prediction of the actual MFI from the validation group. The mean MFI values estimated for CZT SPECT were more than twofold higher in patients with a body weight of 60 kg than in patients with a body weight of 120 kg (15.9 and 6.8 ppm for (99m)Tc-sestamibi and 30.5 and 13.1ppm for (201)Tl, respectively), and for a 14-min acquisition of up to one million myocardial counts, the corresponding injected activities were only 80 and 186 MBq for (99m)Tc-sestamibi and 39 and 91 MBq for (201)Tl, respectively.
  
  
  CONCLUSIONS
  Myocardial activities acquired during exercise CZT SPECT are strongly influenced by body weight and tracer type, and are dramatically higher than those obtained using an Anger camera, allowing very low-dose protocols to be planned, especially for (99m)Tc-sestamibi and in non-obese subjects.
authors.affiliation: Department of Nuclear Medicine, CHU-Nancy, Nancy, 54000, France.
authors.forename: Antoine
authors.initials: A
authors.lastname: Verger
authors.forename: Laetitia
authors.initials: L
authors.lastname: Imbert
authors.forename: Yalcine
authors.initials: Y
authors.lastname: Yagdigul
authors.forename: Renaud
authors.initials: R
authors.lastname: Fay
authors.forename: Wassila
authors.initials: W
authors.lastname: Djaballah
authors.forename: François
authors.initials: F
authors.lastname: Rouzet
authors.forename: Nicolas
authors.initials: N
authors.lastname: Fourquet
authors.forename: Sylvain
authors.initials: S
authors.lastname: Poussier
authors.forename: Véronique
authors.initials: V
authors.lastname: Roch
authors.forename: Dominique
authors.initials: D
authors.lastname: Le Guludec
authors.forename: Gilles
authors.initials: G
authors.lastname: Karcher
authors.forename: Pierre-Yves
authors.initials: PY
authors.lastname: Marie
mesh_terms: D000368:Aged; D002104:Cadmium; D005080:Exercise Test / Q000379:methods; D005260:Female; D015902:Gamma Cameras; D006321:Heart / Q000000981:diagnostic imaging; D006801:Humans; D008297:Male; D008875:Middle Aged; D017256:Technetium Tc 99m Sestamibi / Q000032:analysis / Q000493:pharmacokinetics*; D013691:Tellurium; D013793:Thallium / Q000032:analysis / Q000493:pharmacokinetics*; D015899:Tomography, Emission-Computed, Single-Photon / Q000295:instrumentation* / Q000379:methods; D015032:Zinc
chemical_list: C474490:CdZnTe; D002104:Cadmium; C027549:thallium chloride; D017256:Technetium Tc 99m Sestamibi; D013793:Thallium; D015032:Zinc; D013691:Tellurium