Diagnostic Accuracy of [⁶⁸Ga]Ga-PSMA-11 PET-CT in Characterising Bone Lesions in Prostate Cancer: A Single-Centre...

Precise staging of prostate cancer is vital for treatment planning and prognosis. While [⁶⁸Ga]Ga-PSMA-11 PET-CT has demonstrated high diagnostic accuracy in detecting metastatic disease, the interpretation of indeterminate or potentially benign PSMA-avid bone lesions remains a clinical challenge in routine practice.

We conducted a retrospective single-centre study involving 214 patients who underwent [⁶⁸Ga]Ga-PSMA-11 PET-CT between January 2021 and January 2024. Patients with prior known bone metastases or alternative PSMA radiotracers were excluded. Only those with follow-up imaging were included for diagnostic accuracy analysis. Follow-up modalities included PSMA PET-CT, CT, MRI, and bone scintigraphy. Final classification (metastatic or benign) was based on radiological and clinical assessment. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated using follow-up imaging as the reference standard. Lesions classified as indeterminate were analysed separately and excluded from diagnostic performance calculations.

Of the 214 included patients, 142 had follow-up imaging. Among 80 patients with bone lesions initially reported as metastatic, 74 (92.5%) were confirmed. Among 28 patients initially reported as having benign bone lesions, 26 (92.9%) remained benign on follow-up. Thirty-four patients with indeterminate lesions were reviewed; four were ultimately metastatic. Excluding indeterminate cases, sensitivity, specificity, PPV, and NPV were 97.4%, 86.7%, 94.9%, and 92.9%, respectively. Diagnostic discordance was primarily associated with benign uptake in the ribs, iliac bones, pubic rami and degenerative changes.

[⁶⁸Ga]Ga-PSMA-11 PET-CT shows excellent sensitivity and positive predictive value for detecting metastatic bone disease in prostate cancer. However, benign lesions may also exhibit uptake, emphasising the importance of integrating imaging results with PSA levels, Gleason scores, and TNM staging. Prospective studies are needed to validate these findings and assess their impact on long-term outcomes.