Comparison of Hotelling observer models and human observers in defect detection from myocardial SPECT imaging

The objective of this study was to compare defect detection performance using a channelized Hotelling observer with radially symmetric channel (RSC) and oriented channels (OC) to that found in a previously reported human observer ROC study (see K.J. LaCroix and B.M.W. Tsui, "An evaluation ofthe effect of nonuniform attenuation compensation on defect detection for Tc-99m myocardial SPECT images," J. Nucl. Med., vol. 38, p. 19P, 1997). The observer\´s task involved the detection of left-ventricular myocardial perfusion defects for Tc-99m sestamibi myocardial perfusion SPECT images. The images were reconstructed using the filtered-backprojection (FBP) algorithm without attenuation compensation or the maximum-likelihood expectation-maximization (ML-EM) algorithm with non-uniform attenuation compensation (AC). This was performed for cases with and without significant attenuation artifacts. The areas under the ROC curves for the Hotelling observers were calculated and compared to those for the human observers. The ML-EM reconstructed images (with AC) had high defect detectability across all anatomy types, while with FBP, a lower detectability was found for cases where the reconstructed images contained attenuation artifacts in the myocardium. Similar trends between the channelized Hotelling observer and those from the human observer study were found with both radially symmetric channel (RSC) and oriented-channel (OC) models. Further investigation of the channel models is needed to determine the number and alignment of orientations and the number and cutoff of frequency bands to improve agreement between human and Hotelling observer results.