title: Quantitative evaluation of the administrated dose affecting image quality in myocardial perfusion SPECT.
abstract: BACKGROUND
  Myocardial perfusion imaging (MPI) can provide the valuable cardiac functions.Image quality in nuclear medicine tomography is critically dependent on the activity administered into patients.
  
  
  OBJECTIVE
  This study was designed to evaluate the optimum injected dose of 99mTc-MIBI for quantitative assessment of image quality as compared with standard injected dose used for that purpose.
  
  
  METHODS
  The image quality parameters (Contrast, relative noise and contrast to noise ratio) were determined in 32 patients (21 male, 11 female, age 45-60 y) with weight 60 ± 15 kg. Patients were classified into four groups; each one consisted of 8 patients. The first group received 370 MBq, the second one received 555 MBq, the third group received 740 MBq and the last group received 925 MBq.
  
  
  RESULTS
  Qualitative assessments of the images revealed equivalent scintigraphic patterns in all patients. There was a significant difference in the image contrast. The image contrast in the 370 MBq group was greater than other groups. The image noise between the four groups was significantly different. It increased with injected dose reduction. Contrast to noise ratio (CNR) was significantly different between 370 MBq and other groups.
  
  
  CONCLUSIONS
  It is concluded that results from the first group which received 370 MBq are sufficiently similar to those of the fourth group (standard group) which received 925 MBq. Consequently,accurate estimations of differential cardiac functions are possible with the 370 MBq dose.
authors: Department of Biophysics, Faculty of Science, Cairo University, Cairo, Egypt.
authors: Reem H
authors: RH
authors: El-Gebaly
authors: Nuclear Cardiology Department, Intensive Care Unit, Faculty of Medicine, Cairo University Hospitals, Cairo, Egypt.
authors: Islam K
authors: IK
authors: Maamoun
authors: Department of Biophysics, Faculty of Science, Cairo University, Cairo, Egypt.
authors: Noha G
authors: NG
authors: Madian
mesh_terms: D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D055414:Myocardial Perfusion Imaging / Q000379:methods*; D017256:Technetium Tc 99m Sestamibi / Q000008:administration & dosage*; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods* / Q000592:standards*
chemical_list: D017256:Technetium Tc 99m Sestamibi
keywords: 99mTc-MIBI; image contrast; image noise; image quality; image quality parameters; qualitative assessment