title: [A comparison between attenuation-corrected and -uncorrected transmission-emission SPECT images obtained with Tl-201 in CAD patients].
abstract: BACKGROUND
  The aim of this study was to evaluate the impact of attenuation correction (AC) on the diagnostic accuracy of conventional stress/red thallium SPECT studies.
  
  
  METHODS
  We studied 60 consecutive patients (36 males) who underwent conventional diagnostic stress/red study with and without AC (NAC) using a dual-head SPECT camera (Vertex ADAC) with a 153Gd source. The mean age of these patients was 60 years (30-80) and 29 of the subjects had a history of MI. Reconstructed images were visually analyzed using 20 segments scored on a 5-point scale (0 = normal, 4 = no uptake). Diagnostic accuracy was evaluated in 24 consecutive patients who underwent coronary angiography. Polar plots from each of the four reconstructed data sets per patient were normalized on the maximum and quantified using a nine segment model.
  
  
  RESULTS
  The comparison between the segmental stress score obtained with and without AC showed agreement in 1057 out of 1200 (88%) segments analyzed, K statistic value = 0.67. The number of fixed defects was significantly lower after AC. The diagnostic accuracy, evaluated in 24 patients (480 segs), was not significantly different between AC and NAC analysis (80 vs 84% respectively).
  
  
  CONCLUSIONS
  AC seems to reduce the number of fixed defects due to attenuation artefacts without improving diagnostic accuracy, probably because of the low number of subjects submitted to angiography and of the interpreting bias due to the expertise of the operators. In fact, in the rather small group of patients evaluated, no improvement in diagnostic accuracy was observed, probably because several attenuation defects were not considered pathological due to operator expertise.
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017023:Coronary Angiography; D003327:Coronary Disease / Q000000981:diagnostic imaging*; D005260:Female; D015902:Gamma Cameras; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013794:Thallium Radioisotopes; D015899:Tomography, Emission-Computed, Single-Photon / Q000295:instrumentation / Q000379:methods* / Q000706:statistics & numerical data