[Determination of regional rate of glucose metabolism in lumbar muscles in patients with generalized tendomyopathy using dynamic 18F-FDG PET].

Generalized tendomyopathy (GTM), or fibromyalgia (FM), is a disease characterized by wide-spread pain in the musculoskeletal system which usually begins at a single site, e.g., as low-back pain or cervical syndrome, and develops into generalized pain over months or years. The disorder affects primarily women, beginning around the age of 35 and reaching its peak during or after the menopause. Its etiology is still unknown. Secondary forms are observed particularly in rheumatoid arthritis. In order to get more information on FM we determined the local metabolic rate of glucose in vivo in the skeletal muscle (lumbar region) with dynamic 18F-FDG positron emission tomography (PET). 2 healthy volunteers and 6 female patients with FM reaching in age from 31 to 53 years were scanned. As 18F-FDG PET scanning is a metabolic tool, it is crucial to observe standardized conditions of metabolic steady-state. We used, therefore, the hyperinsulinemic euglycemic insulin clamp technique to stimulate the myogenic glucose uptake under stable plasma-glucose levels. The local metabolic rates of glucose utilization were estimated with a non-linear least squares fit on the 3 compartment 18F-FDG-model. A lumped constant of 0.67 was assumed. Under glucose clamp conditions patients with FM showed a significantly (p < 0.001) lower metabolic rate of glucose (4.3 +/- 1.1) mumol/100 g tissue/min compared with normal volunteers (8.5 +/- 2.3 mumol/100 g/min). Due to a significantly (p < 0.005) increased glucose backflow from tissue into the vascular space (k2 in the kinetic model) the rate of phosphorylation was markedly reduced in patients with FM.(ABSTRACT TRUNCATED AT 250 WORDS)