Impact of Point-Spread Function Reconstruction on 68Ga-DOTATATE PET/CT Quantitative Imaging Parameters

OBJECTIVE. The objective of our study was to investigate the impact of point-spread function (PSI) reconstruction and lesion size on Ga-68-tetraazacyclododecanetetraacetic acid-DPhel-Tyr3-octreotate (DOTATATE) PET/CT quantitative parameters. MATERIALS AND METHODS. A total of 38 patients with 42 Ga-68-DOATATE PET/CT studies and 125 lesions were included. Scans were reconstructed with and without PSF modulation. For each lesion, the maximum standardized uptake value (SUVmax) and peak standardized uptake value (SUVpeak), metabolic tumor volume (MTV), total lesion somatostatin avidity, and tumor somatostatin receptor expression heterogeneity using the AUC method were measured. Intraclass correlation coefficient (ICC) and Bland-Altman analyses were used to compare PSF and non-PSF values. A subgroup analysis was performed to determine the impact of lesion size. RESULTS. Of the 125 lesions, 51 were in the liver, 31 in lymph nodes, 17 in bone, eight in pancreas, four in lung, and 14 in other sites. The ICCs between PSF and non-PSF values were excellent for SUVmax, SUVpeak, MTV, and total lesion somatostatin avidity (ICC = 0.97-0.99), and the ICC was good for tumor somatostatin receptor expression heterogeneity (ICC = 0.81). Comparison of PSF with non-PSF values showed a bias (mean percentage change +/- SD) of 27.5% +/- 14.7% for SUVmax, 15.5% +/- 9.5% for SUVpeak, -18.6% +/- 37.6% for MTV, 0.8% +/- 28.1% for total lesion somatostatin avidity, and -7.1% +/- 11.0% for tumor somatostatin receptor expression heterogeneity. Comparison of PSF with non-PSF values for lesions less than 2 cm (n = 75) showed corresponding biases greater than those for lesions 2 cm or larger (n = 50). CONCLUSION. PSF reconstruction effected higher values for SUVmax and SUVpeak, produced decreased values for tumor somatostatin receptor expression heterogeneity, and had a variable effect on MTV and total lesion somatostatin avidity depending on lesion size.