FDG-PET screening for cerebral metastases in patients with suspected malignancy.

Abstract

2-(18)F-Fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) is increasingly being used in the evaluation of patients with malignancy. Recently, imaging protocols have incorporated ¿whole-body' views acquired over multiple steps. However, with this strategy, brain metastases can potentially go undetected. The aim of this study was to determine whether a supplementary 10-min brain 18F-FDG scan provides additional clinically useful information. Accordingly, we reviewed the studies of 273 patients with various malignancies in whom both whole-body and brain images were performed. Whole-body and regional attenuation-corrected 18F-FDG images were obtained approximately 60 min post-injection. A separate 10-min scan of the brain was subsequently performed. All studies were performed using a standard PET scanner with the images being interpreted by consensus of at least two experienced observers. Altogether, 119 studies were reported as normal (n = 96) or showing anatomic or normal variants (n = 23). Abnormalities involving extracranial organs were identified in 149 (55%) patients. Cerebral metastases were reported in 4 (1.5%) patients, only two of which (0.7%) were unsuspected prior to the PET scan. Incidental pathology (encephalopathy, infarct) was reported but unconfirmed in two further patients (0.7%). We conclude that routine ¿screening' for cerebral metastases in patients with suspected malignancy has a low yield and may not be clinically useful.