Objective: Subjective evaluation of myocardial SPECT is hindered by observer variability. Registering the images to a 3-D template allows an analysis on a voxel by voxel basis. The aim of this work was to evaluate voxel by voxel comparisons of perfusion defects to identify coronary artery disease (CAD).
Method: A male and female normal image template was constructed from normal stress 99mTc tetrofosmin SPECT studies. Twenty-five studies were registered to a standard shape and position creating a mean and standard deviation image for males and females. One hundred and four patients who had been routinely referred for SPECT and angiography were used to assess this approach. The 'gold standard' for CAD was defined by angiography. This group contained 67 males and 37 females. Thirteen patients had severe stenosis in three vessels, 16 with two severe stenosis, 27 with a single severe stenosis and 48 without a severe stenosis. The test group studies were registered to the respective templates. The Z score for each voxel was calculated for all voxels within the myocardium. Low count voxels with a Z-score of greater than 5 were considered abnormal indicating the presence of CAD.
Results: Using this criterion the overall sensitivity and specificity for detecting CAD was 73% and 92%, respectively. The sensitivities for detecting single, double and triple vessel disease were 63%, 75% and 92%, respectively.
Conclusion: The use of an automated statistical mapping approach shows a performance comparable with observers in terms of sensitivity and specificity without inter- and intra-observer variability.
Peace RA, Staff RT, McKiddie FI, Gemmell HG, Metcalfe MJ. Detection of coronary artery disease in myocardial perfusion SPECT using registration and statistical comparisons. Nuc Med Comm 2003; 24: 457-8.
Mr Richard Peace, NGH Unit, Newcastle upon Tyne. Tel: +44 (0)191-233-6161.
Regional Medical Physics Department, Newcastle General Hospital, Newcastle upon Tyne, NE4 6BE, UK.
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