Clinical usefulness of attenuation and scatter correction on Tl-201 SPECT studies using coronary angiography as a reference

The aim of this study was to evaluate the clinical usefulness of both attenuation and scatter correction on Tl-201 SPECT studies. A total of 102 patients (76 males, 26 females) with a mean age of 54 years who were subjected to coronary angiography prior to or following the scintigraphic examination. A Tl-201 one day protocol was used. Simultaneous transmission-emission images were obtained by a gamma camera equipped with an attenuation and scatter correction system based on two moving collimated Gd-153 rod sources. Stress and delayed reconstructed images, uncorrected for attenuation and scatter, were interpreted. One month later, stress and delay reconstructed images corrected for attenuation and scatter were interpreted by the same readers. The results were compared using as reference the coronary angiography findings. A stenosis of 50% or more was considered significant. Attenuation and scatter corrected images demonstrated significant increase in specificity for findings in the right coronary artery territory, i.e. 89% vs. 41% for uncorrected images (p<0.05) with a non-significant loss in sensitivity from 96% to 89%. When we split the population on a gender basis, statistically significant differences in specificity between corrected and non-corrected images were observed in the left anterior descending territory for the females (100% vs. 42%) and in the right coronary artery territory for males (87% vs. 26%). It was concluded that attenuation and scatter correction in Tl-201 SPECT studies may significantly decrease false positive lesions in the inferior wall as well as in the anterior in females. (author)