[11C]Acetate positron emission tomography-computed tomography imaging of prostate cancer lymph-node metastases correlated with histopathological findings after extended lymphadenectomy.

OBJECTIVE

The aim of this study was to determine the efficacy of combined [(11)C]acetate positron emission tomography and computed tomography ([(11)C]acetate-PET/CT) in regional lymph-node staging in patients with prostate cancer (PCa).

MATERIAL AND METHODS

[(11)C]Acetate-PET/CT was performed in 19 PCa patients who subsequently underwent extended pelvic lymph-node dissection (ePLND). The [(11)C]acetate-PET/CT results were compared with the surgical and histopathological findings from 13 defined lymph-node regions.

RESULTS

[(11)C]Acetate-PET/CT was true-positive for lymph-node metastases in nine patients, false-positive in three, false-negative in one patient and true-negative in six. The patient-by-patient-based sensitivity was 90% and the specificity 67%, the positive predictive value (PPV) was 75% and the negative predictive value (NPV) 86%. From a total of 114 nodal regions (mean 5.9 regions per patient), 484 lymph nodes (mean 25.5 nodes per patient) were removed and evaluated histopathologically. Forty-six lymph nodes from 24 out of 114 (21%) nodal regions were positive for PCa metastasis. The nodal-region-based sensitivity of [(11)C]acetate-PET/CT was 62%, specificity was 89%, PPV 62% and NPV 89%.

CONCLUSION

[(11)C]Acetate-PET/CT detects PCa lymph-node metastases with high patient-by-patient-based sensitivity but low specificity, and low nodal-region-based sensitivity but high specificity. Its limited ability to detect microscopic lymph-node involvement makes ePLND essential in all patients diagnosed with positive nodes on [(11)C]acetate-PET/CT.