This CPB has been revised to state that PET scans are considered experimental and investigational for chronic osteomyelitis, infection of hip arthroplasty, and fever of unknown origin. This policy revision is based upon the conclusions of a decision memorandum from the Center for Medicare & Medicaid Services. This CPB is revised to state that PET scans are considered experimental and investigational for the evaluation of neurofibromatosis, ileal carcinoma, malignant thymoma, Paget's disease (including extra-mammary Paget's disease), thymic carcinoma, vulvar cancer, gestational trophoblastic neoplasia, and Langerhans cell histiocytosis. This CPB is revised to delete the indication for PET as an alternative to technetium 99-m bone scans, as the shortage of technetium has been resolved.