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

Abstract

Purpose We studied the effect of varying specific activity of [68Ga]DKFZ-PSMA11 ([68Ga]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 [68Ga]DP11 imaging in mice administered [68Ga]DP11 or [67Ga]DP11 (as a dilution tracer) using imaging and biodistribution studies. Results Region-of-interest (ROI) analysis of the [68Ga]DP11 imaging study indicated that the uptake was constant on same day or consecutive days. Prior imaging with [68Ga]DP11 did not significantly influence the subsequent uptake of [68Ga]DP11. Uptake of [68Ga]DP11 (60 min) and [67Ga]DP11 (24 h) in PC3-PIP tumors was 12.37 ± 4.19 %ID/g and 12.49 ± 6.88 %ID/g, respectively; [68Ga]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 [68Ga]DP11, in a given PSMA+ lesion, is constant under several same-day or serial-day imaging conditions.

Detection Threshold and Reproducibility of 68Ga-PSMA11 PET/CT in a Mouse Model of Prostate Cancer

“…Thus, organ uptake data in small-animal 68 Ga-PSMA11 PET/ CT should be treated with caution. Our findings for interday reproducibility were consistent with previous studies on mice bearing PSMA 1/2 PC3 xenografts (20).…”

“…Likewise, the overall low PET signal (%IA/g) from the blood pool, liver, muscles, and background might have affected interreader and interday reproducibility for organ uptake. Both the high kidney uptake and the very low background, blood, liver, and muscle PET signals are in line with other studies reporting the biodistribution of 68 Ga-PSMA11 in mice (19,20). From day to day and reader to reader, regions of interest could not be placed identically; rather, there was a slight variation in location and, thus, in %IA/g readings.…”

Preclinical Evaluation of a Companion Diagnostic Radiopharmaceutical, [18F]PSMA-1007, in a Subcutaneous Prostate Cancer Xenograft Mouse Model

“…We determined good repeatability for the tumor uptake of [ 18 F]­PSMA-1007 in xenograft mice between the scans from dynamic PET imaging, wCVs, RCs, and ICCs results obtained over two consecutive days. Our findings are comparable to those of previous studies on [ 68 Ga]­Ga-PSMA-11 and [ 68 Ga]­Ga-DP11 in PSMA-positive xenograft mice. , …”

“…Our findings are comparable to those of previous studies on [ 68 Ga]Ga-PSMA-11 and [ 68 Ga]Ga-DP11 in PSMA-positive xenograft mice. 44,45 Furthermore, we found that the inhibition of PSMA by 2-PMPA reduced the AUC of the TAC over 120 min by 37%. The 2-PMPA treatment altered k 2 and k 3 , but not K 1 ; the net influx rate constant K i and concentration in specific binding tissue (C S ) were also reduced in the inhibition group.…”

Cyclotron vs generator-produced 68Ga PSMA: a single-institution, prospective clinical trial

“…The purified sample of 68 Ga showed only two peaks at 511 keV and 1077 keV. Several experiments were performed in mice to determine repeatability of the cyclotron-produced 68 Ga-HBED-CC, which are published in Molecular Imaging and Biology [12] .…”