Optimization of radiochemical purity assessment for [68Ga]Ga-EDOTREOTIDE (Somakit-TOC®): a shortened r-TLC method for improved PET radiopharmaceutical workflow

Background

The increasing use of [⁶⁸Ga]Ga-based radiopharmaceuticals in PET imaging, requires efficient quality control procedures. The standard r-TLC method for verifying [⁶⁸Ga]Ga-EDOTREOTIDE (Somakit-TOC^®) radiochemical purity (RCP) is time-consuming, creating workflow challenges in radiopharmacies. This study evaluates an optimized r-TLC method with a reduced migration distance (4 cm vs. 9 cm) to improve efficiency while maintaining analytical reliability. Tests for specificity, accuracy and robustness were performed using ITLC-SG – Acetate and ITLC-SG – Citrate systems. Additionally, migration time was analyzed to evaluate whether the alternative method could offer added benefits.

Results

The mean Rs for ITLC-SG – Acetate at 4 cm was 2.43 ± 0.28, while for ITLC-SG – Citrate with added [⁶⁸Ga]GaCl₃ was 5.58 ± 0.23, both exceeding the threshold of 1.5. The mean RCP at 4 cm was 98.90% ± 0.25%, and 99.21% ± 0.19% at 9 cm, with [⁶⁸Ga]Ga-uncomplexed remaining within acceptable limits. No [⁶⁸Ga]GaCl₃ was detected. The coefficient of variation (CV) for RCP between methods was < 2% (0.22%). Operator-based analysis yielded a mean Rs of 3.95 ± 0.06 (CV = 1.52%) and a mean [⁶⁸Ga]Ga-EDOTREOTIDE percentage of 99.60% ± 0.03% (CV = 0.03%). Migration times were significantly reduced with the alternative method (85% reduction).

Conclusion

Shortening the migration distance in r-TLC did not compromise specificity, accuracy or robustness while significantly reducing analysis time. The proposed method enhances PET radiopharmaceutical workflows, allowing faster patient dose preparation without quality loss. This approach could be investigated to other [⁶⁸Ga]Ga-labeled compounds, supporting improved clinical and research applications in nuclear medicine.