PET STUDIES WITH ~(18)F-DEOXYGLUCOSE AND ~(15)O LABELLED WATER IN PATIENTS WITH LIVER METASTASES

摘要

Perfusion of the target area is a major parameter for the chemotherapy of liver metastases. Positron emission tomography (PET) and ~(15)O labelled water were used for perfusion studies in patients with liver metastases from colorectal carcinoma and melanoma. All patients were scheduled for chemotherapy using surgically implanted catheters and subcutaneous port systems. Repeated flow studies with ~(15)O labelled water were carried out after intravenous, intra-arterial (hepatic artery), intraportal and intralienal tracer injection (30-100 mCi). Higher tracer concentrations in the lesions were noted after intra-arterial injection in 15 of 18 metastases. In one patient with small metastases (<2 cm), a high tracer accumulation was found only after intraportal injection. In two other cases, a mixed perfusion pattern was observed. As the results demonstrate, PET can be used for repeated perfusion studies. Quantitative evaluation is useful for therapy planning. Different chemotherapeutic protocols are in use for the treatment of patients with metastatic melanomas. PET studies with ~(18)F-deoxyglucose (~(18)FDG) were carried out in order to obtain basic data on metabolism in 128 metastases obtained from 27 patients with metastatic malignant melanoma prior to therapy. Furthermore, 35 metastatic lesions in 12 melanoma patients were examined prior to and after one chemotherapeutic cycle. All patients were studied immediately prior to and after one chemotherapeutic cycle. The average ~(18)FDG uptake was 4.24 standardized uptake value (SUV) in lymph node metastases, 4.17 standardized uptake value SUV for lung metastases and 7.74 SUV for liver metastases prior to therapy. Follow-up PET examinations were performed in six patients who received a combined chemotherapeutic protocol (day 1: dacarba-zine (DTIC); days 2-5: interferon-α). PET was performed prior to therapy, after one day of DTIC therapy and after completion of the chemotherapeutic cycle. Four of the patients showed a decrease in ~(18)FDG uptake after the one day DTIC chemotherapy, followed by an increase after the end of the cycle. A steady increase in tumour metabolism in two patients was noted. The results show that PET with ~(18)FDG can be used to quantify early effects on tumour metabolism and select those patients who will not respond to chemotherapy.