Diagnostic value of 18F-FDG PET/CT delayed imaging after diuresis in patients with primary bladder tumor

Abstract

Objective To explore the diagnostic value of 18F-FDG PET/CT delayed imaging after induced diuresis for primary bladder tumor. Methods Fourteen patients (12 males, 2 females; age range 35-88 years) with pathologically confirmed primary bladder tumor (clinical stage T1-3N0M0) were retrospectively analyzed. All patients underwent standard 18F-FDG PET/CT followed by a delayed (2.5-3.0 h later) pelvic imaging post intravenous injection of 20 mg furosemide and oral intake of 600 ml water. A positive lesion was defined as the uptake of 18F-FDG greater than the urine radioactivity and negative as equaled to or less than the urine radioactivity. Diagnostic efficacy of 18F-FDG PET/CT was calculated with pathology as the gold standard. Mann-Whitney u test was used to analyze data. Results There were 12 malignant (11 urothelium carcinomas and 1 squamous cell carcinoma) and 2 benign tumors (papillary epitheliomas). On standard PET/CT imaging, 3 of 12 malignant lesions showed increased metabolism of 18F-FDG and the other 9 were false negative; while the 2 benign tumors showed no abnormal 18F-FDG uptake. The sensitivity, specificity, and accuracy of 18F-FDG PET/CT were 3/12, 2/2 and 5/14, respectively. Sizes of the 3 18F-FDG-avid malignant lesions were greater than those of other 9 18F-FDG-negative lesions (26, 30, 35 mm vs (15.6±6.3) mm; Z=-2.315, P<0.05). The sensitivity, specificity, and accuracy of delayed pelvic imaging were 11/12, 2/2, 13/14, respectively. Conclusion 18F-FDG PET/CT delayed imaging after diuresis has a high diagnostic efficacy for primary bladder tumor. Key words: Bladder neoplasms; Tomography, emission-computed; Tomography, X-ray computed; Deoxyglucose