Utility of routine preoperative 18F-fluorodeoxyglucose positron emission tomography/computerized tomography in identifying pathological lymph node metastases at radical cystectomy

Purpose:We determined the diagnostic performance of 18F-FDG (fluorodeoxyglucose) positron emission tomography/computerized tomography for detecting nodal metastases in patients with muscle invasive urothelial bladder cancer before radical cystectomy.Materials and Methods:Preoperative 18F-FDG positron emission tomography/computerized tomography scans (208) were retrospectively reviewed. Scans were routinely performed in 185 patients with muscle invasive urothelial bladder cancer between August 2012 and February 2017, all of whom underwent radical cystectomy and pelvic lymph node dissection. Analyses were stratified by clinical node involvement and chemotherapy status. The diagnostic performance of 18F-FDG positron emission tomography/computerized tomography was assessed according to sensitivity, specificity, positive predictive value and negative predictive value.Results:Lymph node metastases at time of pelvic lymph node dissection were present in 21.8% of those without suspicious nodes on computerized tomography (clinically node negative) and 52.6% of those with suspicious nodes on computerized tomography (clinically node positive). Median metastatic focus size was 5 mm. In clinically node negative cases 18F-FDG positron emission tomography/computerized tomography rarely detected nodal metastases (sensitivity 7% to 23%). In clinically node positive cases negative 18F-FDG positron emission tomography/computerized tomography was useful in ruling out lymph node metastases (sensitivity 92% to 100%). This study was limited by its mixed population and focus on pelvic nodal metastases only.Conclusions:18F-FDG positron emission tomography/computerized tomography appears to be most useful for better characterization of enlarged nodes identified by computerized tomography. Routine preoperative 18F-FDG positron emission tomography/computerized tomography has limited utility in clinically node negative cases.