[The usefulness of whole body FDG-PET/CT in patients with brain metastasis]

In patients presenting with brain metastases, the evaluation for extracranial metastases is important to determine the therapeutic strategies and predict the patients outcome. We investigated the findings of whole-body FDG-PET/CT in 30 patients with metastatic brain tumors. The patients were divided into two groups consisting of 16 patients with precocious or synchronous metastases (PS group), or 14 patients with metachronous metastases (M group), according to the brain metastatic patterns. In all patients of the PS group, the primary site was the lung. In one patient of the PS group, the primary lesion was detected neither by FDG-PET/ CT nor by contrast-enhanced CT or MRI in one patient of the PS group. The primary site of another patient in the PS group was confirmed only by FDG-PET/CT. The sensitivity of FDG-PET/CT in search of primary site was 93.3%, while that of conventional modalities was 87.5%. Maximum standardized uptake value (SUV) of the primary lesions did not show statistically significant difference between groups with single and multiple metastatic brain lesions. SUV also failed to show a statistically significant difference between groups with and without extracranial metastatic lesions. In patients comprising the M group, breast cancer was the most frequent primary site. 3 patients in the M group showed no definite hypermetabolic lesions including the primary sites. Two of them have been clinically independent for more than 20 months. 22 (73.3%) of all patients presented extracranial metastases when brain lesions were found. FDG-PET/CT is a useful modality in detecting the primary cancer and evaluating extracranial systemic metastases. It is important to establish a refined clinical staging system and predict the patient's prognosis based upon the findings of FDG-PET/CT in patients with brain metastasis.