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Human-observer receiver-operating characteristic (ROC) results with clinical patient studies indicate that ordered-subset expectation-maximization (OSEM) reconstructions with a combination of corrections for attenuation, scatter, and distance-dependent resolution (DDR) significantly improves perfusion defect detection accuracy over filtered back-projection (FBP) images with no compensation. A recent Monte Carlo study has also shown that for scatter correction (SC) in particular, selection of an appropriate strategy can impact cardiac uniformity. The spatial domain based effective source scatter estimation (ESSE) technique was shown to provide more robust performance in improving cardiac uniformity than the triple-energy window (TEW) method. In this work, we investigate if further improvements in observer performance could be obtained by using the ESSE method of SC instead of the currently employed TEW SC, in combination with attenuation correction (AC) and resolution compensation (RC). We evaluated the effectiveness of the ESSE method to provide additional improvements in image quality objectively by using human-observer ROC studies on clinically acquired patient acquisitions. Results indicate that both ESSE and TEW SC in combination with AC and RC provide significantly higher detection accuracy than FBP with no compensation for the overall detection of coronary artery disease (CAD) as well as in localizing perfusion defects in the left anterior descending (LAD) and left circumflex (LCx) territories. Comparing, the two implementations of SC evaluated in this study, we note that the ESSE method resulted in larger aggregate areas under the ROC curve (Az) in each case. However, a statistically significant improvement over TEW correction was only observed in the LAD territory. This indicates that SC implemented with the ESSE and TEW methods were close in terms of their improvement in detection accuracy for perfusion defects in the clinical images of this investigation, with the ESSE method arguably being slightly better. However, the clinical implementation of ESSE will be hampered by its longer computing time.
Date of Publication: Oct. 2003