title: CT-based attenuation correction in Tl-201 myocardial perfusion scintigraphy is less effective than non-corrected SPECT for risk stratification.
abstract: BACKGROUND
  Previous studies advocate the use of attenuation correction in myocardial perfusion scintigraphy (MPS) for patient risk stratification.
  
  
  METHODS
  Six-hundred and thirty-seven unselected patients underwent Tl-201 MPS by a hybrid SPECT/CT system. Attenuation-corrected (AC) and non-corrected (NAC) images were interpreted blindly and summed stress scores (SSS) were calculated. Study endpoints were all-cause mortality and the composites of death/non-fatal acute myocardial infarction (AMI) and death/AMI/late revascularization.
  
  
  RESULTS
  During a follow-up of 42.3 ± 12.8 months 24 deaths, 13 AMIs and 28 revascularizations were recorded. SSS groups formed according to event rate distribution across SSS values were: 0-4, 5-13, >13 for NAC and 0-2, 3-9, >9 for AC. Kaplan-Meier functions were statistically significant between NAC SSS groups for all study endpoints. AC discriminated only between SSS 0-2 and >9 for death/AMI and between 0-2 and 3-9 for death/AMI/revascularization. In the univariate Cox regression abnormal NAC (SSS > 4) was accompanied with much higher hazards ratios than abnormal AC (SSS > 2). In the multivariate model abnormal AC yielded no significance for either endpoint whereas abnormal NAC proved independent from other covariates for the composite endpoints.
  
  
  CONCLUSIONS
  Our results challenge the effectiveness of CT-based AC for risk stratification of patients referred for MPS.
authors: Department of Nuclear Medicine, University Hospital of Patras, University of Patras, Medical School, Rion, 26500, Patras, Greece.
authors: Christos A
authors: CA
authors: Savvopoulos
authors: Trifon
authors: T
authors: Spyridonidis
authors: Nikolaos
authors: N
authors: Papandrianos
authors: Pavlos J
authors: PJ
authors: Vassilakos
authors: Dimitrios
authors: D
authors: Alexopoulos
authors: Dimitris J
authors: DJ
authors: Apostolopoulos
mesh_terms: D000368:Aged; D000465:Algorithms; D016477:Artifacts; D006115:Greece / Q000453:epidemiology; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D055414:Myocardial Perfusion Imaging / Q000706:statistics & numerical data*; D015995:Prevalence; D011379:Prognosis; D016016:Proportional Hazards Models; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D015996:Survival Rate; D013794:Thallium Radioisotopes; D015899:Tomography, Emission-Computed, Single-Photon / Q000706:statistics & numerical data*; D014057:Tomography, X-Ray Computed / Q000706:statistics & numerical data*
chemical_list: D019275:Radiopharmaceuticals; D013794:Thallium Radioisotopes