18F-Flotufolastat PET/MR in suspicious prostate cancer: correlation with histopathological biopsy-results

Ziel/Aim: Several studies have proven that prostate-specific membrane antigen (PSMA) positron emission tomography/magnetic resonance imaging (PET/MRI) exceeds the results of solo use of multiparametric (mp) MRI in the primary detection of prostate cancer (PC). Therefore, the aim of this retrospective study was to determine the detection efficacy of ¹⁸F-flotufolastat (formerly ¹⁸F-rhPSMA-7.3) PET/MRI using the recently introduced PRIMARY score for PET assessment of tumour lesions in correlation to results from biopsy.

Methodik/Methods: In total, 72 patients (median pre-scan PSA 10.1 ng/mL) undergoing clinically indicated ¹⁸F-flotufolastat PET/MRI were included. ¹⁸F-Flotufolastat PET and MR-images of the prostate were read independently using the PRIMARY and MR-PIRADS score. Imaging scores on patient-basis were compared to transrectal biopsy results (clinically significant (cs) PC ISUP≥2) performed at a median time interval of 42 days (range 10-265 days) after PET. Diagnostic performance parameters were calculated and ROC-analyses were performed on a patient-basis.

Ergebnisse/Results: In total, 20 (27.8%) patients were recorded as csPC. Sensitivity, specificity, PPV and NPV were 85.0%, 80.8%, 62.9% and 93.3% for PRIMARY score and 85.0%, 50.0%, 39.5% and 90.0% for MR-PIRADS score, respectively. Using combined PET and MRI, sensitivity, specificity, PPV and NPV were 95.0%, 42.3%, 38.8%, 95.7%, respectively. ROC analysis revealed an AUC of 0.82 (95% CI 0.71-0.90), 0.75 (95% CI 0.63-0.84) and 0.88 (95% CI 0.78-0.94) for PRIMARY score, Pi-RADS-score and combined PET/MRI score, respectively. The comparison of PRIMARY score, Pi-RADS score and PET/MRI ROC-curves did not reach significance (p=0.14 vs. p=0.13 vs. p=0.06).

Schlussfolgerungen/Conclusions: The PRIMARY score for detecting biopsy-proven primary PC lesions on ¹⁸F-flotufolastat PET outperformed sole mpMR imaging using Pi-RADS score showing higher diagnostic performance parameters. Thus, the PRIMARY score should be considered when interpreting intraprostatic ¹⁸F-flotufolastat PET images.

Publication History

Article published online:
12 March 2025