The study included 1,026 PET scans ordered for evaluation of a single pulmonary nodule or lung cancer staging. Twenty-six patients had distant metastases found on whole-body FDG PET; 25 of the 26 had metastases located within the confines of what would have been a thoracic PET examination, said Suzanne L. Aquino, MD, thoracic radiologist at Massachusetts General Hospital in Boston. A whole-body FDG PET examination covers from the skull base to mid-thigh. A thoracic PET examination covers from the skull base through the kidneys.
All patients with distant metastases had lymph node disease, Dr. Aquino said. One patient had a distant metastasis only seen on whole body PET. She had advanced nodal disease, and therefore her management would not have significantly changed following the whole body PET examination, Dr. Aquino said.
Despite the positive results of the study, Dr. Aquino recommends proceeding with caution. If CT indicates that the patient has a local lung cancer and there are no indications that the cancer has spread to the lymph nodes, then thoracic PET is enough, she said. However, if nodal disease is suspected, the patient should undergo a whole body PET examination to detect the extent of metastases, Dr. Aquino said. Treatment varies dramatically between patients with limited lung cancer (surgical treatment) and those with cancer spread (nonsurgical treatment), so it is essential that appropriate measures be taken to diagnose metastases, Dr. Aquino added.
Thoracic PET examinations require less radiation than whole-body PET examinations when obtained with a dual PET/CT scanner. In addition, a thoracic PET examination takes 20 to 35 minutes less than a whole body examination, said Dr. Aquino. "In a busy PET center, this time savings could mean reduced delays in scheduling patients as well as less motion artifact during image acquisition," Dr. Aquino noted.
Dr. Aquino will present the study on May 5 during the American Roentgen Ray Society Annual Meeting in Miami Beach, FL.