The
nucleoside 5-fluoro-2-deoxyuridine is a
pyrimidine analogue accumulating in proliferative cells. We prospectively evaluated biodistribution of the PET tracer [(18)F]5-fluoro-2-
deoxyuridine (FdUrd), its value for imaging malignant
tumors, and its correlation to both [(18)F]
2-fluoro-2-deoxyglucose (FDG)-PET findings and histological proliferation indices. In 11 previously untreated patients (5 lung
carcinoma; 3
soft tissue sarcoma; 2 gastrointestinal
carcinoma; 1
non-Hodgkin lymphoma [NHL]), mean doses of 290 MBq FdUrd and 390 MBq FDG were administered intravenously on subsequent days. Static PET scans were initiated 50-70 min after administration and the mean standardized uptake values (SUV) were calculated. Dynamic emission FdUrd scans were performed in 8/11 patients. Time-activity curves of blood and
tumors as well as SUV of
tumor lesions and organs were calculated. Proliferative activity was evaluated by Ki-67 immunohistostaining of biopsies. Tracer accumulated physiologically in liver, kidney, and bladder. SUVs were: kidney, 4.8 +/- 0.66; liver, 4.1 +/- 0.36; vertebrae, 0.70 +/- 0.17; spleen, 0.37 +/- 0.06; lungs, 0.19 +/- 0.05; femora/humeri, 0.14 +/- 0.03. Five patients exhibited significant intratumoral FdUrd-uptake (2
sarcomas; 1 NHL; 2 lung
carcinomas) with mean SUVs ranging from 0.7 to 10.5.
Metastases were not detected. Time-activity curves showed a rapid initial increase of intratumoral activity followed by activity retention. FDG-PET was positive in 10/11 patients. Correlation between the SUV of FdUrd-PET and FDG-PET or the tissue proliferation index, respectively, was not significant. FdUrd was a suitable tracer for imaging malignant
tumors only in exceptional cases:
Sarcoma, NHL, and some lung
carcinomas were detected. FdUrd-PET was less effective than FDG-PET. In this group of patients, it was not useful in measuring tissue proliferation.