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Objective To explore the diagnostic value of delayed 18 F?FDG PET/CT pelvic imaging after forced diuresis in detecting male patients with locally recurrent rectal cancer. Methods Thirty?two male patients ( 32-79 years) with clinically suspicious recurrences of rectal cancer were retrospectively ana?lyzed. All patients underwent a standard 18 F?FDG PET/CT followed by a delayed pelvic imaging after 2.5 h of administration of 20 mg furosemide intravenously and extra water intake of 500 ml at least. Final diagnosis was made by pathology or clinical follow?up (>10 months ) . Diagnostic efficiency of 18 F?FDG PET/CT standard and delayed pelvic images were calculated and compared. χ2 test was used for data analysis. Re?sults A total of 25 patients were diagnosed with recurrent rectal cancer, including 10 cases with invasion of surrounding tissue, and 5 cases with metastases. Among the 7 patients without local recurrences, 2 had dis?tant metastases. The sensitivity, specificity, and accuracy of standard FDG PET/CT were 92.0%(23/25), 3/7, 81.2%(26/32), respectively. The corresponding values of the delayed imaging were 96.0%(24/25), 6/7, and 93.8%(30/32), respectively. The specificity of delayed imaging was higher than that of standard FDG PET/CT (χ2=14.333, P0.05) . The urina?ry bladder activity reached or approached the background during the delayed imaging. Twenty?two malignant lesions of surrounding invasion were confirmed. The positive rate of delayed imaging was higher than that of standard FDG PET/CT:95.5%(21/22) vs 63.6%(14/22);χ2=6.400, P<0.05. Conclusions 18F?FDG PET/CT delayed pelvic imaging after diuresis and hydration is useful for eliminating the artifacts from urina?ry bladder activity, and for detecting the invasion to the rectal surrounding tissue more effectively. It could be a supplement to standard FDG PET/CT.
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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 positivelesion 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.