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

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 T_1-3N₀M₀) 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. (authors)