Repeatability of [ 68 Ga]DKFZ11-PSMA PET Scans for Detecting Prostate-specific Membrane Antigen-positive Prostate Cancer.

PURPOSE: We studied the effect of varying specific activity of [68 Ga]DKFZ-PSMA11 ([68 Ga]DP11) on repeated imaging of prostate-specific membrane antigen-positive (PSMA+) xenograft tumors.

PROCEDURES: Athymic nude mice bearing PC3-PIP (PSMA+) and PC3 (PSMA-) bilateral flank tumors were assessed to study intra- and inter-day repeatability of [68 Ga]DP11 imaging in mice administered [68 Ga]DP11 or [67 Ga]DP11 (as a dilution tracer) using imaging and biodistribution studies.

RESULTS: Region of interest (ROI) analysis of the [68 Ga]DP11 imaging study indicated that the uptake was constant on the same day or consecutive days. Prior imaging with [68 Ga]DP11 did not significantly influence the subsequent uptake of [68 Ga]DP11. Uptake of [68 Ga]DP11 (60 min) and [67 Ga]DP11 (24 h) in PC3-PIP tumors was 12.37 ± 4.19 %ID/g and 12.49 ± 6.88 %ID/g, respectively; [68 Ga]DP11 was 13.83 ± 3.77 and 17.76 ± 1.84 on same-day and 15.98 ± 5.82 %ID/g on second-day imaging.

CONCLUSIONS: This study demonstrates that [68 Ga]DP11, in a given PSMA+ lesion, is constant under several same-day or serial-day imaging conditions.