title: Dose reduction in half-time myocardial perfusion SPECT-CT with multifocal collimation.
abstract: Recent technological advances in myocardial perfusion imaging may warrant the use of lower injected activity. We evaluated whether quantitative measures of stress myocardial perfusion defects using Tc-99m sestamibi and low-energy high-resolution (LEHR) collimators are equivalent to lower dose SPECT-CT with cardiac multifocal collimators and software (IQ·SPECT).
  
  
  
  93 patients underwent one-day rest-stress gated SPECT-CT. Following conventional rest imaging, 925-1100 MBq (25-30 mCi) of Tc-99m sestamibi was injected during stress testing. Stress SPECT-CT images were acquired two ways: with LEHR (13 minutes) and IQ·SPECT (7 minutes). Low-dose IQ·SPECT stress was simulated by subsampling the full-dose data to half-, quarter-, and eighth-count levels. Abnormalities were quantified using the total perfusion deficit (TPD) score and dose-specific databases.
  
  
  
  The mean ± SD of the differences between LEHR and IQ·SPECT TPD scores were -1.01 ± 5.36%, -0.10 ± 5.81%, 1.78 ± 4.81%, and 1.75 ± 6.05% at full, half, quarter, and eighth doses, respectively. Differences were statistically significant for quarter and eighth doses. Correlation between LEHR and IQ·SPECT was excellent at all doses (R ≥ 0.93). Bland-Altman plots demonstrated minimal bias.
  
  
  
  With IQ·SPECT, quantitative stress SPECT-CT imaging is possible with half of the standard injected activity in half the time.
authors.affiliation: Division of Nuclear Medicine, Department of Radiology, Brigham and Women's Hospital, Boston, MA, USA. mlyon@invicro.com.|Department of Radiology, Harvard Medical School, Boston, MA, USA. mlyon@invicro.com.|inviCRO, 27 Drydock Ave, Boston, MA, 02210, USA. mlyon@invicro.com.
authors.forename: Morgan C
authors.initials: MC
authors.lastname: Lyon
authors.affiliation: Division of Nuclear Medicine, Department of Radiology, Brigham and Women's Hospital, Boston, MA, USA.
authors.forename: Courtney
authors.initials: C
authors.lastname: Foster
authors.affiliation: Molecular Imaging, Siemens Medical Solutions USA, Inc., Hoffman Estates, IL, USA.
authors.forename: Xinhong
authors.initials: X
authors.lastname: Ding
authors.affiliation: Division of Nuclear Medicine, Department of Radiology, Brigham and Women's Hospital, Boston, MA, USA.|Department of Radiology, Harvard Medical School, Boston, MA, USA.
authors.forename: Sharmila
authors.initials: S
authors.lastname: Dorbala
authors.affiliation: Molecular Imaging, Siemens Medical Solutions USA, Inc., Hoffman Estates, IL, USA.
authors.forename: Don
authors.initials: D
authors.lastname: Spence
authors.affiliation: Molecular Imaging, Siemens Medical Solutions USA, Inc., Hoffman Estates, IL, USA.
authors.forename: Manojeet
authors.initials: M
authors.lastname: Bhattacharya
authors.affiliation: Molecular Imaging, Siemens Medical Solutions USA, Inc., Hoffman Estates, IL, USA.
authors.forename: A Hans
authors.initials: AH
authors.lastname: Vija
authors.affiliation: Division of Nuclear Medicine, Department of Radiology, Brigham and Women's Hospital, Boston, MA, USA.|Department of Radiology, Harvard Medical School, Boston, MA, USA.
authors.forename: Marcelo F
authors.initials: MF
authors.lastname: DiCarli
authors.affiliation: Division of Nuclear Medicine, Department of Radiology, Brigham and Women's Hospital, Boston, MA, USA.|Department of Radiology, Harvard Medical School, Boston, MA, USA.
authors.forename: Stephen C
authors.initials: SC
authors.lastname: Moore
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D005080:Exercise Test / Q000379:methods; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000295:instrumentation / Q000379:methods*; D008297:Male; D008875:Middle Aged; D055414:Myocardial Perfusion Imaging / Q000379:methods*; D011829:Radiation Dosage; D000069079:Radiation Exposure / Q000032:analysis / Q000517:prevention & control*; D011835:Radiation Protection / Q000295:instrumentation / Q000379:methods*; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D000072098:Single Photon Emission Computed Tomography Computed Tomography / Q000295:instrumentation / Q000379:methods*; D017256:Technetium Tc 99m Sestamibi; D013997:Time Factors
chemical_list: D019275:Radiopharmaceuticals; D017256:Technetium Tc 99m Sestamibi
keywords: SPECT; collimation; dose reduction; myocardial perfusion imaging