Value of true whole-body FDG-PET/CT scanning protocol in oncology: optimization of its use based on primary diagnosis

Abstract

No standardized field of view (FOV) currently exists for whole-body (WB) positron emission tomography/computed tomography (PET/CT). Limited WB PET/CT FOV can exclude portions of the head, upper, and lower extremities, because there is little perceived clinical benefit to be gained from imaging these areas. To determine how often utilizing WB PET/CT changes the clinical stage and management compared to each of the limited WB FOVs used for PET/CT. We retrospectively identified 556 oncologic patients (804 PET/CT studies) who underwent staging or restaging PET/CT between November 2010 and November 2011. Abnormal hypermetabolic areas that were suspicious for malignancy in areas that are outside of some of the limited fields of view including in the brain, scalp, and calvarium (above the orbital ridge), in the proximal upper extremity (distal to the humeral neck), distal upper extremity (beyond the elbow), proximal lower extremity (distal to the lesser trochanter), and distal lower extremity (beyond the knees) were recorded. A total of 8.5% (47/556) of patients had abnormal findings outside the most limited FOV (skull base to upper thighs) used in PET/CT. More patients had abnormal hypermetabolic lesions in the lower extremity (5.9%) than in the upper extremity (2.3%). Similarly, more patients had abnormal lesions in the proximal (6.5%) compared to the distal (1.4%) upper and lower extremities. The stage was only changed in one patient (0.2%), however new lesions noted in the brain changed management in six patients (1.1%). Melanoma, lymphoma, multiple myeloma, sarcomas and stage IV lung, breast, prostate, bladder, testicular, and renal cancer were more likely to have findings outside the most limited FOV (skull base to upper thighs). WB FOV detects additional sites of disease compared to the limited WB FOV, and although these lesions rarely change stage, some of these lesions may change clinical management.