The diagnostic accuracy of [99mTc]Tc-PSMA SPECT/CT for recurrent prostate cancer based on individual patient attributes.

The diagnostic performance of [Tc]Tc-PSMA SPECT/CT is contingent upon the individual attributes of the patients' prostate cancer. The aim of the study was to analyse these relationships in order to suggest thresholds that may guide diagnostic decision-making regarding the appropriate use of [Tc]Tc-PSMA SPECT/CT imaging.  METHODS: A total of 143 patients with recurrent prostate cancer were treated with 664.0 ± 43.9 MBq of [Tc]Tc-MIP-1404 and imaged by SPECT/CT. Comparisons with PSA serum level, ISUP grade, PSA doubling time and PSA velocity were performed. It was ensured that a familywise error rate of α was maintained in multiple-group comparisons.  RESULTS: Stratifying patients by ISUP grade revealed distinct PSA-dependent detection profiles. For patients with ISUP grade 1-3, the PSA-dependent detection rates at PSA ≤ 0.2 ng/ml, > 0.2-0.5 ng/ml,> 0.5-1.0 ng/ml, > 1.0-2.0 ng/ml,> 2.0-5.0 ng/ml and > 5.0 ng/ml were 15%, 25%, 50%, 60%, 60% and 94%, respectively. For patients with ISUP grade 4-5, these were 29%, 75%, 83%, 86%, 90%, and 100%. PSA velocity did not result in a sharper risk stratification for using [Tc]Tc-MIP-1404 SPECT/CT.  CONCLUSIONS: [Tc]Tc-MIP-1404 SPECT/CT is a valuable diagnostic option for patients with recurrent prostate cancer and ISUP grades 4-5 at PSA >0.2 ng/ml or PSA-DT ≤ 12 months and ISUP grades 1-3 at PSA > 0.5 ng/ml or PSA-DT ≤ 6.0 months. If PSMA PET/CT is available, it should be preferred at ISUP grade 1 or PSA < 0.2 ng/ml.