Cerebral lesions incidentally detected on 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography images of patients evaluated for body malignancies.

Objectives: The purpose of this work was done to evaluate the value of including the brain in the field of view of a whole-body 2-deoxy-2-[18F] fluoro-D-glucose positron emission tomography (FDG-PET) study of patients referred for the evaluation of body malignancies.

Methods: A total of 1026 consecutive patients were included in this work. The primary diagnoses were the following: lung (n = 253), colorectal (n = 148), head and neck (n = 61), lymphoma (n = 249), melanoma (n = 84), and others (n = 231). Whole-body FDG images including the brain were acquired with a dedicated PET tomograph (GE advance, General Electronic Medical Systems, Milwaukee, WI) one hour after the intravenous administration of 10 mCi of FDG. Two experienced nuclear medicine physicians interpreted the images. Positive findings in the brain or the skull were correlated with other imaging studies and clinical follow-up.

Results: Abnormal findings were detected in 3.9% (40/1026) of the patients. Among the 40 abnormal focal lesions, 29 patients had a known history of cerebral disease, cerebrovascular or metastatic disease in most patients. Of the 11 patients without a prior history of cerebral disease, four patients had increased focal FDG uptake suggestive of metastases. Among these, two were proven clinically, one was proven to be a skull base metastasis on MRI, and the other had negative clinical follow-up, but only of two months duration. The other seven patients had a decreased focal FDG uptake most consistent with infarct, one was proven clinically, and the other six had a negative clinical follow-up (mean of 6.3 months, range 1-10), but had multiple risk factors for cerebrovascular disease.

Conclusions: We conclude that FDG-PET screening for cerebral lesions in patients with body malignancy has little clinical impact. Unsuspected cerebral or skull metastases were detected in 0.4% (4/1026) of the patients.