A perception experiment to assess the clinical accuracy of various methods of obtaining cardiac phase images

The role of expert system shell induction in the analysis of phase and amplitude images obtained from nuclear cardiology

In an attempt to explain the results of a perception experiment, estimates of statistical parameters were obtained from phase and amplitude images of nuclear medicine multiple-gated cardiac studies. A commercially available induction system was used to create a rule-based decision tree using these estimates as a training set. In the classification of normal and abnormal studies two useful rules were found; one of these involved the standard deviation of the left ventricular phase histogram and the other concerned the correlation of adjacent pixels in the left ventricular region of the amplitude image. A discriminant analysis performed on five amplitude and five phase parameters produced no better discrimination than the use of the phase standard deviation alone. Although it was hoped that induction would find more than two useful rules, the results of the discriminant analysis confirm that induction has performed creditably on a difficult problem.

Perceptual and statistical analysis of cardiac phase and amplitude images

A perceptual experiment was conducted using cardiac phase and amplitude images. Estimates of statistical parameters were derived from the images and the diagnostic potential of human and statistical decisions compared. Five methods were used to generate the images from 75 gated cardiac studies, 39 of which were classified as pathological. The images were presented to 12 observers experienced in nuclear medicine. The observers rated the images using a five-category scale based on their confidence of an abnormality presenting. Circular and linear statistics were used to analyse phase and amplitude image data, respectively. Estimates of mean, standard deviation (SD), skewness, kurtosis and the first term of the spatial correlation function were evaluated in the region of the left ventricle. A receiver operating characteristic analysis was performed on both sets of data and the human and statistical decisions compared. For phase images, circular SD was shown to discriminate better between normal and abnormal than experienced observers, but no single statistic discriminated as well as the human observer for amplitude images.