IMPACT OF SCATTER CORRECTION IN PLANAR SCINTIMAMMOGRAPHY - A PHANTOM STUDY

This study examines how scatter correction might affect lesion detecti on and quantitation of tumor-to-normal breast tissue activity ratio in planar scintimammography. Methods: Forty-one phantom acquisitions wer e performed to mimic a wide variety of scintimammographic imaging cond itions in which lesions would be close to the chest wall. For each acq uisition, the images corresponding to a 10% energy window (I10) and tw o scatter correction methods [the Jaszczak (JA) method and a factor an alysis (FA)-based method] were obtained in addition to the conventiona l 20% image (I20). A total of 368 images in which detection of the ''t umor'' was judged borderline were selected, and 10 independent observe rs were asked to detect lesions in these images. Receiver operating cu rve analyses were performed to assess detection performance. Tumor-to- normal tissue activity ratios were calculated for quantitative analysi s. Results: Detection performance significantly improved for the I10, JA and FA images compared to the I20 images, with an increase in sensi tivity up to 8% for FA images. Sensitivity was especially increased fo r small lesions (13- and 16-mm(3) spheres) and true heart-to-normal ti ssue activity ratios of >12. Scatter correction also increased the cer tainty with which the readers gave their judgment. The tumor-to-normal tissue activity ratio was similar to 8% larger on JA or FA images and 1% larger on the I10 images compared to the I20 images. For a given i mage, the variability with which this ratio was estimated was reduced by similar to 4% on JA and FA images. Conclusion: Based on these phant om results, scatter correction might be used with benefit in scintimam mography.