This study examines how scatter correction might affect lesion detection and quantitation of tumor-to-normal breast tissue activity ratio in planar scintimammography.
Methods: Forty-one phantom acquisitions were performed to mimic a wide variety of scintimammographic imaging conditions in which lesions would be close to the chest wall. For each acquisition, the images corresponding to a 10% energy window (110) and two scatter correction methods [the Jaszczak (JA) method and a factor analysis (FA)-based method] were obtained in addition to the conventional 20% image (120). A total of 368 images in which detection of the "tumor" was judged borderline were selected, and 10 independent observers were asked to detect lesions in these images. Receiver operating curve analyses were performed to assess detection performance. Tumor-to-normal tissue activity ratios were calculated for quantitative analysis.
Results: Detection performance significantly improved for the I10, JA and FA images compared to the 120 images, with an increase in sensitivity up to 8% for FA images. Sensitivity was especially increased for small lesions (13- and 16-mm3 spheres) and true heart-to-normal tissue activity ratios of > 12. Scatter correction also increased the certainty with which the readers gave their judgment. The tumor-to-normal tissue activity ratio was approximately 8% larger on JA or FA images and 1% larger on the I10 images compared to the 120 images. For a given image, the variability with which this ratio was estimated was reduced by approximately 4% on JA and FA images.
Conclusion: Based on these phantom results, scatter correction might be used with benefit in scintimammography.