Investigation on pain factors and ethanol concentration predictive value in 68Ga-labeled PET imaging agent injection

Intravenous injection of 68Ga-labeled PET radiopharmaceuticals often causes injection pain, which reduces patient comfort and may induce vascular spasm. Ethanol is widely used as a stabilizer in 68Ga tracers, but quantitative evidence linking ethanol concentration to injection pain and its predictive value remains insufficient. This study aimed to explore independent pain-influencing factors and verify whether ethanol concentration can predict moderate-severe injection pain, so as to provide evidence for optimizing clinical radiopharmaceutical preparation and injection workflow. A total of 181 patients were enrolled. Pain scores were positively correlated with female gender, injection volume and ethanol concentration, and negatively correlated with age. Multivariate logistic regression confirmed ethanol concentration as an independent risk factor for moderate/severe injection pain (OR = 6.63, 95%CI:3.80–11.56, P < 0.001). ROC analysis showed ethanol concentration had an AUC of 0.892 for predicting moderate-severe pain, with an optimal cutoff value of 7.85% (sensitivity 82.8%, specificity 85.4%). Stratified analysis proved that controlling ethanol concentration below 7.85% significantly lowered pain severity and the incidence of moderate-severe pain. Ethanol concentration in 68Ga-labeled PET imaging agents is an independent predictive factor for moderate-to-severe injection pain. Limiting ethanol concentration under 7.85% can effectively relieve injection pain and improve patient experience during nuclear medicine examinations. This quantitative threshold can be directly adopted in routine radiopharmaceutical preparation to reduce injection-related vascular irritation and discomfort for patients.