title: Radio-adaptive Response in Myocardial Perfusion Imaging Induced by Technetium-99m.
abstract: OBJECTIVE
  Low dose radiation will induce adaptation and following exposure to an adaptive dose, the cells are more resistance to following challenging doses. This phenomenon is known as radio-adaptive response. The aim of this study was to investigate the percentage of apoptotic cells in the peripheral blood samples of the patients which undergo myocardial perfusion imaging (MPI) with technetium-99m (Tc-99m) before thallium scan to assess the induction of radio-adaptive response.
  
  
  METHODS
  In this study, 97 samples from 74 patients, referred to nuclear medicine center of Mazandaran Heart Hospital for MPI, which had no history of diagnostic, therapeutic, occupational, and radioactive exposures during past 2 years, were provided. The participants were classified into four groups including control, patients which were scanned solely with technetium, the patients which examined by thallium and the last group were the patients that examined by technetium followed by thallium. Then 2 ml Peripheral blood samples were obtained, and after 24 h incubating, the samples were studied by neutral comet assay. Statistical analysis was carried out using Student'st-test along with one-way analysis of variance.
  
  
  RESULTS
  The mean percentage of apoptotic cells in the exposed groups were higher than the control. Furthermore, among exposed groups, the apoptotic cells in thallium group were more than others and this index was significantly lower in the group which was undergone technetium administration before thallium scan.
  
  
  CONCLUSIONS
  These findings suggest that exposure to Tc-99m could induce a radio-adaptive response against the exposure of thallium-201.
authors.affiliation: Cellular and Molecular Biology Research Center, Babol University of Medical Sciences, Babol, Iran.
authors.forename: Mohammad Mehdi
authors.initials: MM
authors.lastname: Shirazi
authors.affiliation: Cellular and Molecular Biology Research Center, Babol University of Medical Sciences, Babol, Iran; Department of Medical Physics, Babol University of Medical Sciences, Babol, Iran.
authors.forename: Ali
authors.initials: A
authors.lastname: Shabestani-Monfared
authors.affiliation: Department of Medical Physics, Mazandaran University of Medical Sciences, Sari, Iran.
authors.forename: Maryam
authors.initials: M
authors.lastname: Shahidi
authors.affiliation: Department of Nuclear Medicine, Babol University of Medical Sciences, Babol, Iran.
authors.forename: Mehrangiz
authors.initials: M
authors.lastname: Amiri
authors.affiliation: Department of Nuclear Medicine, Mazandaran University of Medical Sciences, Sari, Iran.
authors.forename: Seyed Mohammad
authors.initials: SM
authors.lastname: Abedi
authors.affiliation: Cellular and Molecular Biology Research Center, Babol University of Medical Sciences, Babol, Iran.
authors.forename: Sajad
authors.initials: S
authors.lastname: Borzoueisileh
authors.affiliation: Department of Medical Physics, Babol University of Medical Sciences, Babol, Iran.
authors.forename: Kourosh Ebrahim Nejad
authors.initials: KE
authors.lastname: Gorji
keywords: Myocardial perfusion imaging; radio-adaptive response; technetium; thallium