Purpose: [18F]PSMA-1007 offers advantages of low urinary tracer excretion and improved resolution for imaging prostate cancer. However, non-specific bone lesions (NSBLs), defined as mild to moderate focal bone uptake without a typical morphological correlate on CT, are a common finding on [18F]PSMA-1007 PET/CT. The purpose of this study was to investigate the clinical outcomes of patients with [18F]PSMA-1007 avid NSBLs, to determine whether patients with NSBLs represent a higher risk clinical cohort, and to determine whether SUVmax can be used as a classifier of bone metastasis.
Methods: A retrospective audit of 214 men with prostate cancer was performed to investigate the clinical outcomes of [18F]PSMA-1007 avid NSBLs according to defined criteria. We also compared the serum PSA, Gleason score and uptake time of patients with [18F]PSMA-1007 avid NSBLs to patients without [18F]PSMA-1007 avid bone lesions. Finally, we assessed whether SUVmax is a good classifier of bone metastases using ROC curve analysis.
Results: No [18F]PSMA-1007 avid NSBLs met criteria for a likely malignant or definitely malignant lesion after a median 15.8-month follow-up interval (11.9% definitely benign, 50.3% likely benign, and 37.7% equivocal). There were no statistically significant differences in serum PSA, Gleason score and uptake time between patients with [18F]PSMA-1007 avid NSBLs and those without [18F]PSMA-1007 avid bone lesions. All NSBLs with adequate follow-up had SUVmax ≤11.1. When comparing NSBLs to definite prostate cancer bone metastases, the highest SUVmax value recorded was a good classifier of bone metastasis, and an SUVmax cut-point of ≥7.2 maximised the Youden’s index.
Conclusion: [18F]PSMA-1007 avid NSBLs rarely represent prostate cancer bone metastases. When identified in the absence of definite metastatic disease elsewhere, it is appropriate to classify those with SUVmax <7.2 as likely benign. NSBLs with SUVmax 7.2-11.1 may be classified as equivocal or metastatic, with patient clinical risk factors, scan appearance, and potential management implications used to guide interpretation.
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Posted 22 Mar, 2021
Received 17 Mar, 2021
Invitations sent on 15 Mar, 2021
On 13 Mar, 2021
On 12 Mar, 2021
Posted 22 Mar, 2021
Received 17 Mar, 2021
Invitations sent on 15 Mar, 2021
On 13 Mar, 2021
On 12 Mar, 2021
Purpose: [18F]PSMA-1007 offers advantages of low urinary tracer excretion and improved resolution for imaging prostate cancer. However, non-specific bone lesions (NSBLs), defined as mild to moderate focal bone uptake without a typical morphological correlate on CT, are a common finding on [18F]PSMA-1007 PET/CT. The purpose of this study was to investigate the clinical outcomes of patients with [18F]PSMA-1007 avid NSBLs, to determine whether patients with NSBLs represent a higher risk clinical cohort, and to determine whether SUVmax can be used as a classifier of bone metastasis.
Methods: A retrospective audit of 214 men with prostate cancer was performed to investigate the clinical outcomes of [18F]PSMA-1007 avid NSBLs according to defined criteria. We also compared the serum PSA, Gleason score and uptake time of patients with [18F]PSMA-1007 avid NSBLs to patients without [18F]PSMA-1007 avid bone lesions. Finally, we assessed whether SUVmax is a good classifier of bone metastases using ROC curve analysis.
Results: No [18F]PSMA-1007 avid NSBLs met criteria for a likely malignant or definitely malignant lesion after a median 15.8-month follow-up interval (11.9% definitely benign, 50.3% likely benign, and 37.7% equivocal). There were no statistically significant differences in serum PSA, Gleason score and uptake time between patients with [18F]PSMA-1007 avid NSBLs and those without [18F]PSMA-1007 avid bone lesions. All NSBLs with adequate follow-up had SUVmax ≤11.1. When comparing NSBLs to definite prostate cancer bone metastases, the highest SUVmax value recorded was a good classifier of bone metastasis, and an SUVmax cut-point of ≥7.2 maximised the Youden’s index.
Conclusion: [18F]PSMA-1007 avid NSBLs rarely represent prostate cancer bone metastases. When identified in the absence of definite metastatic disease elsewhere, it is appropriate to classify those with SUVmax <7.2 as likely benign. NSBLs with SUVmax 7.2-11.1 may be classified as equivocal or metastatic, with patient clinical risk factors, scan appearance, and potential management implications used to guide interpretation.
Figure 1
Figure 2
Figure 3
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