Experimental approach for optimizing dose regimen of 68 Ga-DOTATATE PET/CT for neuroendocrine tumor (NET) imaging in current high sensitivity scanners: Phantom and Patient Study

Abstract

Aim This study aimed to determine the optimized scan time and injected activity regimen for clinical (68) Ga DOTATATE PET/CT in neuroendocrine tumor imaging through an experimental approach without using machine learning techniques.Methods A NEMA PET body phantom was used with Ga- (68) to simulate a 9:1 sphere-to-background ratio. PET data were acquired on a high-sensitivity scanner at various scan times (15-300 s/bed). For each scan time, coefficient of variation (COV) and contrast-to-noise ratio (CNR) were calculated. The minimum scan time (T (min) ) needed to meet the Rose Criterion (CNR > 5) for the smallest sphere was identified. This T (min) was then applied to patient scans with neuroendocrine tumors (originally acquired at 120 s/bed) to evaluate image quality and determine an optimized activity regimen for clinical (68) Ga-DOTATATE PET imaging.Results Phantom experiments showed that a COV (max )of 20 is the highest acceptable noise level for detecting the smallest lesions, corresponding to a minimum scan time of about 1 minute per bed position. Patient image analysis confirmed that all tumors visible at routine scan times were still detectable at this minimum duration. This supports the use of a lower activity regimen (~1 MBq/kg), which can reduce patient radiation exposure compared to the standard 1.85 MBq/kg protocol.Conclusion This work demonstrated that scan time and activity for(68) Ga-DOTATATE NET imaging can be significantly minimized without compromising image interpretation and quantification.