Pelvic Lymph Node Staging by Combined18F-FDG-PET/CT Imaging in Bladder Cancer Prior to Radical Cystectomy.
Accurate lymph node (LN) staging in bladder cancer before radical cystectomy is essential as LN metastases have an independent prognostic value. Most studies used a cutoff of > 10 mm in detecting pelvic LN spread. The aim of this study was to evaluate the diagnostic accuracy of contrast-enhanced computed tomography (CT) and18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) alone, or combined for preoperative pelvic LN staging.



We retrospectively analyzed the data of 70 bladder cancer patients that were staged with18F-FDG-PET/CT before radical cystectomy between 2012 and 2015.18F-FDG-PET images were analyzed visually and semi-quantitatively by calculating the maximum standardized uptake value. CT scans were reviewed using different cutoffs of pelvic LNs, with the best cutoff at 8 mm (area under the curve = 0.684).



Metastatic LNs were confirmed in 53 (2.8%) of 1906 resected LNs in 11 (15.7%) patients. Sensitivity, specificity, and accuracy were 54.5%, 89.8%, and 84.3% for18F-FDG-PET alone; 45.5%, 91.5%, and 84.3% for CT (LNs > 8 mm) alone; and 27.3%, 96.6%, and 85.7% for CT (LNs > 10 mm) alone, respectively. Combined18F-FDG-PET/CT resulted in a nonsignificant increase of diagnostic accuracy using a cutoff > 8 mm for LN evaluation (63.6%, 86.4%, and 82.9%, respectively). A significant improvement of sensitivity to 63.6% was achieved only when LNs > 10 mm were considered suspicious (P = .046), but this reduced specificity to 88.1% (P = .025).



Combined18F-FDG-PET/CT does not seem to be justified in preoperative staging if the threshold of pelvic LNs is set > 8 mm.
Department of Urology, Medical University Innsbruck, Innsbruck, Austria. Electronic address: Renate.Pichler@i-med.ac.at.
Renate
R
Pichler
Department of Radiology, Medical University Innsbruck, Innsbruck, Austria.
Tobias
T
De Zordo
Department of Medical Statistics, Informatics, and Health Economics, Medical University Innsbruck, Innsbruck, Austria.
Josef
J
Fritz
Department of Nuclear Medicine, Medical University Innsbruck, Innsbruck, Austria.
Alexander
A
Kroiss
Department of Radiology, Medical University Innsbruck, Innsbruck, Austria.
Friedrich
F
Aigner
Department of Urology, Medical University Innsbruck, Innsbruck, Austria.
Isabel
I
Heidegger
Department of Nuclear Medicine, Medical University Innsbruck, Innsbruck, Austria.
Irene
I
Virgolini
Department of Urology, Medical University Innsbruck, Innsbruck, Austria.
Wolfgang
W
Horninger
Department of Nuclear Medicine, Medical University Innsbruck, Innsbruck, Austria.
Christian
C
Uprimny
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015653:Cystectomy; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism*; D006801:Humans; D008198:Lymph Nodes / Q000000981:diagnostic imaging / Q000473:pathology*; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D010388:Pelvis; D000072078:Positron Emission Tomography Computed Tomography / Q000379:methods*; D011379:Prognosis; D019275:Radiopharmaceuticals / Q000378:metabolism*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D001749:Urinary Bladder Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
CT; Cystectomy; Lymph node metastases; PET; Preoperative staging