Effect of un-attenuation correction on qualitative and semiquantitative lesion detectability in whole-body FDG PET imaging

Objective To investigate the effect of unattenuation correction on qualitative and quantitative lesion detectability in whole body FDG PET imaging. Methods Whole body PET studies were performed in 12 normal subjects and 52 patients with various tumors 50 min after a bolus injection of 18 F FDG.Transmission and emission data were acquired. Reconstructed attenuation corrected and uncorrected images were analyzed qualitatively and semiquantitatively. Results Attenuation corrected and uncorrected images were found to be equally sensitive for detecting lesions. There was a strong linear correlation between lesion to background(L/B) calculated on attenuation corrected and uncorrected images( r=0.93,P 0.01),and no significant difference between them( t=1.89,P 0.05). Conclusions The efficacy of attenuation uncorrected images in qualitatively evaluating tumors is similar to that in attenuation corrected images. Uncorrected images could also provide semiquantitative information, but L/B ratio is the only available index. The anatomic location of tumors in attenuation corrected images was better than in uncorrected ones.