Quantitative Analysis of 68Ga-DOTATATE PET/CT

The ⁶⁸Ga-DOTATATE PET/CT images were analyzed using Hybrid Viewer software (version 5.1.0; Hermes Medical Solutions, Sweden). The SUV_max was calculated with a spherical volume of interest (VOI) tool. The VOI was drawn manually in the primary tumor, the liver (ie, physiological uptake), and the left psoas major muscle (ie, background). The VOI for the primary tumor was dependent on the tumor size. A fixed VOI of 4 cm³ was used for the right lower lobe of the liver, and a fixed VOI of 2 cm³ was used for the middle of the left psoas major muscle. If multiple tumor lesions were present, for practical reasons, the lesion with the highest ⁶⁸Ga-DOTATATE uptake was chosen to calculate the SUV_max. Independent of the scanner used, we determined the following ⁶⁸Ga-DOTATATE PET/CT parameters:
Although SUV_max TLR is most clinically relevant due to the physiological high uptake and the frequent presence of metastases in the liver, an SUV_max TLR ≥ 8.1 appears to be associated with a longer PFS in patients treated with SSA and was therefore also included in our multivariable analysis.^{10 (link),19 (link)}