[Observer variations in computerized 201 thallium myocardial scintigraphy]

The observer variation (reproducibility) in computerized 201Tl scintigraphy was determined by describing the results of 20 investigations as being normal, suggestive of ischaemia or representing scar tissue. At an interval of two months, two physicians evaluated the results independently. As to normality, the interobserver variation was small, the level of agreement corrected for chance agreement, the kappa coefficient, being from 69-100%. For the diagnosis of ischaemia, kappa was also high, 58-100%. The intraobserver variations were of the same magnitude. In scar tissue, the kappa coefficients were somewhat lower. The present method has an acceptable observer variation in distinguishing between a diseased and a normal myocardium. The lower kappa coefficients for scar tissue and recent findings showing that persistent defects on the delayed images are viable tissue in 30% of the cases, makes it difficult to diagnose scar tissue.