Delayed F-FDG PET/CT Appearance of Urachal Adenocarcinomas.

BACKGROUND

Urachal carcinoma is a rare urological malignancy. Use of F-FDG PET/CT in urological oncology has developed slowly because of the urinary elimination of F-FDG. We investigated whether delayed postdiuretic F-FDG PET/CT could be used for diagnosing urachal carcinoma.

METHODS

This retrospective study included 6 patients who underwent delayed postdiuretic F-FDG PET/CT for the evaluation of urachal carcinoma. The delayed postdiuretic PET/CT parameters and clinical characteristics of urachal carcinoma were investigated.

RESULTS

There was no significant difference in the SUVmax between the primary tumors and the urine in the bladder before delayed diuresis (25.4 ± 19.5 vs. 42.9 ± 31.1, =0.18). However, the SUVmax of the primary tumors was significantly higher than the SUVmax of urine after delayed diuresis (25.4 ± 19.5 vs. 3.5 ± 1.6, =0.002). Diuretic F-FDG PET/CT was positive in all patients when compared with normal liver tissues or urine after delayed diuresis. The SUVmax, TLR, and TUR of the primary tumors were 25.4 (range: 7.2-58.9), 7.0 (range: 1.8-14.7), and 6.8 (range: 3.8-11.3), respectively. Delayed postdiuretic F-FDG PET/CT had a negative predictive value of 100% (5/5) for predicting lymph node metastasis. One patient received chemotherapy after radical resection of urachal carcinoma because F-FDG PET/CT found lung metastases, and one patient only received chemotherapy because PET/CT found peritoneal and skeletal metastases.

CONCLUSIONS

Delayed postdiuretic F-FDG PET/CT is a useful tool for the preoperative evaluation of urachal carcinoma. F-FDG PET/CT may improve clinical decision making and management of urachal carcinomas.