title: Influence of extracardiac activity and perfusion abnormalities on myocardial perfusion gated SPECT parameters: interobserver analysis.
abstract: OBJECTIVE
  Extracardiac activity (ECA) may affect interpretation of gated SPECT myocardial perfusion studies (MPSs). To solve this problem, available softwares include myocardial edge delimitation.
  
  
  OBJECTIVE
  To evaluate the influence of ECA in automatic myocardial edge detection under normal conditions and with abnormal perfusion and also evaluate the reproducibility of semi-automatic processing.
  
  
  METHODS
  A total of 100 MPSs, 50 with ECA, were analyzed. Each subgroup included 25 cases with perfusion abnormalities. The cases were processed automatically and by 4 independent operators with different levels of experience. Commercial QGS and QPS softwares were used with tools to mask and relocate the left ventricle area. Functional parameters (final diastolic and systolic volumes and ejection fraction) and perfusion parameters such as the reversibility perfusion score and rest perfusion defect extension were analyzed. The data were compared with Pearson's correlation and Student's test.
  
  
  RESULTS
  Interobserver correlation significantly worsened with the presence of ECA and was moderately affected by perfusion abnormalities. More experienced observers presented better correlation. Reproducibility was greater for the functional perfusion parameters, independently of the observer's experience.
  
  
  CONCLUSIONS
  ECA significantly affects automatic edging delimitation, affecting the MPS values. Interobserver reproducibility with manual processing was more altered regarding functional parameters than in the perfusion scores. Perfusion abnormalities did not interfere with software reproducibility, and when present, better correlation was found. If ECA is not present, manual intervention should be avoided.
authors.affiliation: Nuclear Medicine Section, Medicine Department, University of Chile, Clinical Hospital, Santos Dumont 999-1E, Independencia, Santiago, Chile. rodrigo@jaimovich.cl
authors.forename: R
authors.initials: R
authors.lastname: Jaimovich
authors.forename: D
authors.initials: D
authors.lastname: Gutiérrez
authors.forename: H
authors.initials: H
authors.lastname: Lavados
authors.forename: C
authors.initials: C
authors.lastname: Aqueveque
authors.forename: L
authors.initials: L
authors.lastname: Quevedo
authors.forename: R
authors.initials: R
authors.lastname: Alay
authors.forename: T
authors.initials: T
authors.lastname: Massardo
mesh_terms: D000368:Aged; D016477:Artifacts; D001331:Automation; D055426:Cardiac-Gated Single-Photon Emission Computer-Assisted Tomography; D005260:Female; D006801:Humans; D007422:Intestines / Q000000981:diagnostic imaging; D008099:Liver / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000000981:diagnostic imaging* / Q000473:pathology; D055414:Myocardial Perfusion Imaging; D015588:Observer Variation; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D015203:Reproducibility of Results; D012984:Software; D013318:Stroke Volume; D017256:Technetium Tc 99m Sestamibi / Q000493:pharmacokinetics; D013794:Thallium Radioisotopes / Q000493:pharmacokinetics; D014018:Tissue Distribution
chemical_list: D019275:Radiopharmaceuticals; D013794:Thallium Radioisotopes; D017256:Technetium Tc 99m Sestamibi