Quantitative 99mTc-Galacto-RGD2 SPECT/CT to Evaluate Lung Cancer Physiology and Malignancy: A Comparative Multi-center Study with 18F-FDG PET/CT

132 Objectives 99mTc-Galacto-RGD2 (RGD) has been reported as a feasible tracer to assess tumor angiogenesis and metastasis, but limited to quantitatively evaluate tumor physiology and malignancy by only conventional SPECT/CT imaging. We aim to quantify integrin-αvβ3 expression in lung tumors with quantitative RGD SPECT and compare physiological parameters with glucose metabolism by FDG PET. Methods Twenty-eight biopsy-confirmed patients with non-small cell lung cancer were enrolled to receive both RGD SPECT/CT and FDG PET/CT scans at three medical centers in China. RGD SPECT images were reconstructed with full physical corrections (attenuation, scatter, collimator blur and noise) while PET images were processed according to the clinical routine. All SPECT, SPECT/CT and PET/CT cameras were pre-qualified to enter the study and cross calibrated imaging factors to measure radionuclide concentration in (Bq/ml). Localization of tumors in lung regions was performed by SPECT-CT and PET-CT image fusion. RGD and FDG SUVmax, SUVmean and metabolic volume (MTV, threshold蠅45% SUVmax) were measured and compared to assess the malignancy of lung tumors. Results When measuring Tc99m and F18 radionuclide concentration in cylindrical phantom, all SPECT, SPECT/CT and PET/CT cameras were able to achieve >97% accuracy. Total number of lung tumors (41 vs 43), SUVmax (7.74±3.38 vs 8.81±2.91), SUV mean (3.67±1.23 vs 4.46±1.38) found by RGD SPECT and FDG PET were comparable. Among matched tumors (n=38), linear correlation of RGD and FDG SUVmax was strong (y=0.49x, R=0.78) while correlations for SUVmean and MTV were moderate (SUVmean: y=0.38x, R=0.67; MTV: y=0.97x, R=0.28) (All p<0.0001). Increased RGD SUVmax highly corresponded with increased FDG SUVmax to indicate elevated tumor malignancy. Conclusions Quantitative 99mTc-Galacto-RGD2 SPECT/CT with full physical corrections is a feasible approach to measure tumor integrin-αvβ3 expression. It can provide another insight to quantitatively assess tumor physiology and malignancy beside FDG PET/CT scan. [Research supported by the Natural Science Foundation Grant, China (#: 81560686) and Mongolia Technology Grant, Mongolia, China (#: kjt15sf01)] $$graphic_D934AD14-B389-4C4C-B5AD-3ED21814FC93$$ $$graphic_B842C79F-2953-486C-A6CA-E15B01D497E4$$ $$graphic_C6091FA4-3A44-4C7E-8752-EBE26992A1A2$$