Detection of urinary tract tumors by ¹⁸F-FLT PET/CT

Objectives The aim of this study is to investigate the efficacy of ¹⁸F-FLT PET/CT for detection of primary and metastatic lesions of urinary tract tumors.

Methods Twenty-one (15 men, 6 women) patients were examined by ¹⁸F-FLT PET/CT (Siemens Biograph 16). All the patients received surgical operation or biopsy and the tumor was diagnosed histopathologically.

Results In 21 patients examined by ¹⁸F-FLT PET/CT, 12 were confirmed histopathologically to be urothelial cell carcinoma, 6 renal cell carcinoma, 2 retroperitoneal liposarcoma, and 1 bladder carcinoma. Five patients had lung metastases, 2 had lymph node metastases, and 1 had gallbladder cancer synchronously. In 7 of the 12 patients with urothelial carcinoma and 1 with bladder carcinoma, the primary tumor could not be detected due to retention of urine in the ureter and urinary excretion of ¹⁸F-FLT. In the other 5 patient with urothelial cell carcinoma, 2 with retroperitoneal liposarcoma, and 1 with renal cell carcinoma, the primary tumor could be detected due to lack of urinary excretion of ¹⁸F-FLT by renal insufficiency. ¹⁸F-FLT uptake in the tumor site expressed as SUVmax in ¹⁸F-FLT PET was 2.17-28.99 (mean±S.D. 98.51±11.50) in urothelial cancer, 1.65 in renal cell carcinoma, and 9.35 and 4.24 (6.8±3.61) in retroperitoneal liposarcoma. Lung metastases after nephrectomy for renal cell carcinoma in 5 patients could be detected (SUVmax: 3.24-6.44 (4.45±1.13)). Lymph node metastases in 5 patients also could be detected (SUVmax:2.16-6.35 (4.45±1.73)).

Conclusions Usually, ¹⁸F-FLT PET/CT is not suitable for detection of the primary lesions of urinary tract tumors because of its urinary excretion, whereas their metastatic lesions can be detected by ¹⁸F-FLT PET/CT. Nevertheless, in patients whose urinary excretion of ¹⁸F-FLT is disturbed by renal failures, ¹⁸F-FLT PET/CT is useful for detection of the primary lesions of urinary tract tumors.