Evaluation of dynamic total-body [68Ga]Ga-HER2 Affibody PET/CT in HER2-positive breast cancer: biodistribution, dosimetry and earliest feasible imaging time

[ 68 Ga]Ga-HER2 Affibody PET/CT enables non-invasive, quantitative assessment of HER2 expression in HER2-positive breast cancer. This dynamic total-body PET/CT study aimed to assess the biodistribution and dosimetry of [ 68 Ga]Ga-HER2 Affibody in patients with HER2-positive breast cancer and to identify the earliest feasible imaging time without compromising image quality. Time-activity curve (TAC) analysis revealed that the mean standardized uptake value (SUVmean) in normal organs peaked early and then declined progressively, whereas lesions exhibited sustained tracer accumulation. The mean effective dose of the [ 68 Ga]Ga-HER2 Affibody tracer was 2.90E-02 ± 2.77E-03 mSv/MBq. For 10‑min reconstructions, image quality improved with longer acquisition times. However, no significant differences were observed in lesion detection, tracer uptake, lesion-to-background ratio (LBR), or signal-to-noise ratio (SNR) between the 40–50 min and 50–60 min windows (all P > 0.05). Within the 40–50 min window, 5-min reconstructions from 45 to 50 min showed no significant differences in the SUV, lean-body-mass-normalized standardized uptake value (SUL), SNR, or LBR compared with the 50–60 min images. Using dynamic total-body PET/CT, this study provided a real-time biodistribution profile of [ 68 Ga]Ga-HER2 Affibody in humans and confirmed its safety. Preliminary results indicated that 45 min post-injection was the earliest feasible imaging time for patients with HER2-positive breast cancer. This finding may help streamline clinical workflows and reduce patient waiting times. Name of the registry: Chinese Clinical Trial Registry. Trial registration number: ChiCTR2400092565. Date of registration: 19 November 2024. URL of trial registry record: https://www.chictr.org.cn/index.html .