Integrated analysis of ¹⁸F-FDG PET/CT improves preoperative lymph node staging for patients with invasive bladder cancer

Objectives: Preoperative ¹⁸F-fluoro-2-deoxy-D-glucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) is controversial to assess lymph node (LN) staging in patients with invasive bladder cancer. We proposed to use the maximum standardized uptake value (SUV_max) associated with axial-based LN size to improve the detection of regional LN metastasis.

Methods: From May 2015 to May 2017, we prospectively included patients with urothelial bladder cancer who underwent radical cystectomy with extended pelvic LN dissection. All patients underwent preoperative ¹⁸F-FDG PET/CT staging before surgery. The gold standard comparator was the pathological examination of resected LNs. The data were reported on a regional per area- and patient-based model according to SUV_max values and axial-based LN size criteria.

Results: In total, 1012 LNs were identified in 61 patients with clinically localized invasive bladder cancer who underwent radical cystectomy and extended pelvic LN dissection. Loco-regional involvement of 24 LN areas was confirmed in 17 patients. In per area analysis, diagnostic accuracy of PET/CT and CT alone were respectively 84% and 78% (p = 0.039). On patient-based analysis, combined PET/CT correctly classified pelvic LN status in 5/61 (+ 8%) additional patients using optimal thresholds compared to CT alone, with accuracies of 82% and 74%, respectively (p = 0.13).

Conclusion: Combining SUV_max and axial-based LN size criteria using ¹⁸F-FDG PET/CT improved the diagnostic accuracy for preoperative LN staging in patients with invasive bladder cancer, in per area analysis.

Key points: • Combining metabolical and morphological features using¹⁸F-FDG PET/CT improves the detection of malignant lymph node in patients with bladder cancer. • ¹⁸ F-FDG PET/CT may help for initial staging of patients with muscle invasive bladder cancer.