RESUMO
INTRODUCTION: The aim of this investigation was to evaluate the clinical usefulness of both attenuation and scatter correction in 201Tl SPECT studies. METHODS: We studied 102 patients (76 males, 26 females, mean age 54 years) who underwent coronary angiography prior to or after a scintigraphic examination. A 201Tl 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 153Gd rod sources. Stress and delay reconstructed images, uncorrected for attenuation and scatter, were diagnosed. One month later, stress and delay reconstructed images corrected for attenuation and scatter were diagnosed by the same readers. The results were compared using the coronary angiography findings as reference. A stenosis 50% or larger was considered significant. RESULTS: Attenuation and scatter corrected images demonstrated a 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%). CONCLUSION: Attenuation and scatter correction in 201Tl SPECT studies may significantly decrease false positive lesions in the inferior wall as well as in the anterior in females.
