Purpose: Before locally ablative treatment of colorectal liver metastases, patients have to be carefully evaluated to decide whether this is the adequate therapy. In this study we determined the value of FDG-PET in comparison to conventional staging procedures.
Patients, methods: In 68 consecutive patients referred for laser induced thermotherapy (LITT) of liver metastases from colorectal cancer, pretherapeutic staging with conventional imaging (thoracic and abdominal CT, liver MRI, chest X-ray) and FDG-PET was performed. The examinations were analysed separately and blinded. Based on the staging information, therapeutic decisions were made by an interdisciplinary review board according to a standardized algorithm. The results were compared between conventional imaging and FDG-PET, and were validated by clinical follow up data and histopathology, respectively.
Results: On FDG-PET 210 lesions were interpreted as tumour manifestations. 48 of these were not seen on conventional imaging (true positive, n = 46). In contrast, 24 lesions were visualized by conventional imaging only (true positive, n = 12). Compared to conventional imaging, discrepant findings on FDG-PET led to treatment modifications in 25 patients (37%); these were correct in 20/25 patients. According to the actual treatment course, the inadequate treatment modifications in the remaining 5 patients were avoided by further diagnostic procedures (i.e. biopsies).
Conclusion: In the evaluation of patients with known liver metastases from colorectal cancer before LITT, FDG-PET depicts relevant findings subsidiary to conventional imaging and thus is of high value for therapeutic decision making.