Other patients present with more subtle signs of possible systemic disease, particularly constitutional symptoms such as fatigue, anorexia, or weight loss. Further investigation to find possible metastatic disease is warranted, given that the clinical evaluation for systemic metastases has a high FP rate.12 A PET scan is a reasonable alternative to a battery of other imaging studies. However, it must be realized that there are also many indeterminate findings on PET imaging that may require a battery of additional studies or interventions. Nevertheless, the data demonstrate that PET is more accurate than conventional imaging. In a study5 of 100 patients with lung cancer, PET imaging for distant metastases had a sensitivity of 91%, a specificity of 96%, a FP rate of 5%, and a FN rate of 7%. In contrast, conventional imaging was found to have a sensitivity of 80%, a specificity of 80%, a FP rate of 24%, and a FN rate of 17%.5 Furthermore, PET is more reliable when compared specifically with a radionucleotide bone scan. The sensitivity of PET imaging for detecting bone metastases is 90 to 92%, the specificity is 98%, the FN rate is 1 to 2%, and the FP rate is 8 to 10%,5,23 as opposed to an average sensitivity of 76%, specificity of 69%, FP rate of 63%, and FN rate of 9% for bone scanning in patients with lung cancer.12 Thus, the ability of PET to detect distant metastases is high, and the interpretation of a positive or negative PET result in an individual patient can be made with relative confidence. However, conventional imaging of the brain is still required, because the high glucose metabolism of the brain makes FDG-PET a poor imaging test in this organ.