Biodistribution and radiation dosimetry of [^99mTc]Tc-N4-BTG in patients with biochemical recurrence of prostate cancer.

Rinscheid, Andreas; Gäble, Alexander; Wienand, Georgine; Dierks, Alexander; Kircher, Malte; Günther, Thomas; Patt, Marianne; Bundschuh, Ralph A.; Lapa, Constantin; Pfob, Christian H.

Background: In patients with prostate cancer (PCa), imaging with gastrin-releasing peptide receptor (GRPR) ligands is an alternative to PSMA-targeted tracers, particularly if PSMA expression is low or absent. [99mTc]Tc-N4-BTG is a newly developed GRPR-directed probe for conventional scintigraphy and single photon emission computed tomography (SPECT) imaging. The current study aims to investigate the safety, biodistribution and dosimetry of [99mTc]Tc-N4-BTG in patients with biochemical recurrence (BCR) of PCa. Results: No adverse pharmacologic effects were observed. Injection of [99mTc]Tc-N4-BTG resulted in an effective dose of 0.0027 ± 0.0002 mSv/MBq. The urinary bladder was the critical organ with the highest mean absorbed dose of 0.028 ± 0.001 mGy/MBq, followed by the pancreas with 0.0043 ± 0.0015 mGy/MBq, osteogenic cells with 0.0039 ± 0.0005 mGy/MBq, the kidneys with 0.0034 ± 0.0003 mGy/MBq, and the liver with 0.0019 ± 0.0004 mGy/MBq, respectively. No focal tracer uptake suggestive of PCa recurrence could be revealed for any of the patients. Conclusion: [99mTc]Tc-N4-BTG appears to be a safe diagnostic agent. Compared to GRPR-targeted PET tracers, this 99mTc-labelled SPECT agent could contribute to a broader application and better availability of this novel approach. Further research to assess its clinical value is warranted.

SINGLE-photon emission computed tomography; RADIATION dosimetry; CANCER relapse; PROSTATE cancer; DISEASE relapse; PROSTATE; HOLMIUM; PANCREAS

EJNMMI Research, 2024, Vol 14, Issue 1, p1

2191-219X

Academic Journal

10.1186/s13550-024-01105-6