Abstract
Rationale: 68Ga-ABY-025 is a radiolabelled Affibody molecule for in vivo diagnosis of HER2 positive breast cancer tumours with positron emission tomography (PET). The aim of the present work was to measure biodistribution and estimate radiation dosimetry of 68Ga-ABY-025 for two different peptide doses in a single group of patients using dynamic and serial whole-body PET/CT. Methods: Eight patients diagnosed with varying expression of HER2 in breast cancer metastases were included. Each patient underwent a 45 min dynamic and three whole-body PET/CT scans at 1, 2 and 4 h after injection of low peptide dose (LD) and high peptide dose (HD), with approximately the same amount of radioactivity, in separate investigations one week apart. Absorbed doses were calculated using Olinda/EXM 1.1. Results: Of the major organs, the highest radionuclide uptake at 1, 2 and 4 h p.i. was observed in the kidneys and liver. The highest absorbed organ doses were seen in kidneys followed by liver for both LD and HD 68Ga-ABY-025. Absorbed doses to liver and kidneys were slightly but significantly higher for LD. Total effective dose was 0.030 ± 0.003 mSv/MBq for LD and 0.028 ± 0.002 mSv/MBq for HD. Conclusion: Effective dose for a typical 200 MBq administration is 6.0 mSv for LD and 5.6 mSv for HD. Therefore, from a radiation dosimetry point of view, HD is preferred for PET/CT evaluation of HER2-expressing breast cancer tumours.
- Copyright © 2016 by the Society of Nuclear Medicine and Molecular Imaging, Inc.