title: The value of attenuation correction by hybrid SPECT/CT imaging on infarct size quantification in male patients with previous inferior myocardial infarct.
abstract: BACKGROUND
  Attenuation correction (AC) has been shown to improve the accuracy of myocardial perfusion single photon emission computed tomography (SPECT) for the detection and evaluation of patients with coronary artery disease. Attenuation artifacts, because of diaphragmatic attenuation, frequently affect the evaluation of the inferior wall, especially in male patients.
  
  
  OBJECTIVE
  The aim of this study was to evaluate the value of AC for the assessment of infarct size in coronary artery disease patients after inferior myocardial infarction.
  
  
  METHODS
  Gated-SPECT with Tc-labeled compounds with AC by hybrid SPECT/computed tomography (CT) was performed in 56 male patients with documented previous inferior myocardial infarction. Both corrected and uncorrected SPECT images were processed after motion and scatter correction by ordered-subset expectation maximization iterative reconstruction. When needed, a manual realignment between SPECT and computed tomography (CT) sections was performed. Uncorrected and corrected SPECT images were analyzed for perfusion using a 5-point segmental scoring scale from 0 (normal) to 4 (absent). Summed stress score (SSS), summed rest score (SRS), and summed difference score (SDS) of the inferior left ventricle wall (inferoseptal, inferior, infero-apical and infero-lateral segments) were determined and compared with the regional wall motion score as determined by uncorrected gated-SPECT.
  
  
  RESULTS
  The SSS, SRS, SDS for attenuation-uncorrected and attenuation-corrected studies were 14.02 ± 7.9, 9.51 ± 7, 4.5 ± 3.2 and 9.39 ± 7.1, 5.6 ± 6.1, 3.8 ± 2.8, respectively. Differences were statistically significant (P<0.0001) for SSS and SRS but not for SDS. The regional summed rest score of the inferior wall (SRS of inferior segments) showed a better correlation with the regional summed wall motion score of the same segments: R²=0.50 in comparison to uncorrected SRS, R²=0.46.
  
  
  CONCLUSIONS
  The combination of diaphragmatic attenuation and inferior myocardial infarction determines an artifactual overestimation of infarct size of inferior infarcts. The AC regional perfusion score (SRS) correlates with the regional wall motion score of the inferior wall. AC does not affect the detection and size of residual ischemia (SDS).
authors: Chair of Nuclear Medicine, University of Brescia, Spedali Civili di Brescia, Italy. giubbini@med.unibs.it
authors: Raffaele Mario Tarquinio
authors: RM
authors: Giubbini
authors: Sara
authors: S
authors: Gabanelli
authors: Silvia
authors: S
authors: Lucchini
authors: Giuseppe
authors: G
authors: Merli
authors: Erinda
authors: E
authors: Puta
authors: Carlo
authors: C
authors: Rodella
authors: Federica
authors: F
authors: Motta
authors: Barbara
authors: B
authors: Paghera
authors: Pierluigi
authors: P
authors: Rossini
authors: Arturo
authors: A
authors: Terzi
authors: Francesco
authors: F
authors: Bertagna
mesh_terms: D000368:Aged; D016477:Artifacts; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D007091:Image Processing, Computer-Assisted / Q000379:methods; D056989:Inferior Wall Myocardial Infarction / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D055414:Myocardial Perfusion Imaging / Q000379:methods*; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D017256:Technetium Tc 99m Sestamibi; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods*; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging*
chemical_list: D019275:Radiopharmaceuticals; D017256:Technetium Tc 99m Sestamibi