Metabolic parameters analysis of F-FDG PET/CT in the diagnosis and differential diagnosis of collecting duct carcinoma.

PURPOSE

This study aims to explore the diagnostic performance of F-FDG PET/CT in distinguishing collecting duct carcinoma (CDC) from clear cell renal cell carcinoma (ccRCC).

METHODS

A retrospective analysis was conducted on 11 patients with CDC and 27 patients with ccRCC who underwent F-FDG PET/CT examinations. Clinical indicators and the SUVmax, tumor-to-liver standardized uptake value ratio (TLR), tumor-to-kidney standardized uptake value ratio (TKR), metabolic tumor volume (MTV) and total lesion glycolysis (TLG) values of the primary tumor, whole-body MTV (WBMTV), and whole-body TLG (WBTLG) based on a baseline PET scan, were recorded and compared between the two groups. To assess the discriminative power of these metabolic parameters between CDC and ccRCC, we performed a receiver operating characteristic (ROC) curve analysis.

RESULTS

The median age of the 11 CDC patients was 59 years. All CDC patients were in advanced stages (18% stage III and 82% stage IV). Compare with ccRCC patients, CDC patients had higher lymph node metastases rates (72.7% vs. 22.2%, = 0.008) and distant metastases rates (81.8% vs. 22.2%, = 0.001). The primary tumor in CDC also showed higher SUVmax (10.5 vs. 4.0, < 0.001), TLR (3.9 vs. 1.4, < 0.001), TKR (4.4 vs. 1.5, < 0.001), MTV (53.2 vs. 9.5, = 0.021), and TLG (305.7 vs. 30.4, = 0.0069) than ccRCC. The WBMTV and WBTLG of CDC patients were also higher than the ccRCC group (144.1 vs. 9.5, = 0.0013 and 528.4 vs. 30.4, = 0.0013, respectively). ROC curve analysis revealed no significant differences in the ability of SUVmax, TLR and TKR to differentiate CDC from ccRCC. Median survival for CDC was 36 months, worse for older patients.

CONCLUSION

The utilization of F-FDG PET/CT can assist to detect the metastases and provide guidance for diagnosis and staging. Metabolic parameters obtained from F-FDG PET/CT hold promise for distinguishing CDC from ccRCC.