Nuclear medicine studies of aging--IV. Femoral proximal to distal radionuclide uptake gradient.

Analyses of radionuclide bone scans were carried out to determine if, with the aging process, there were measurable changes in the femoral gradient of activity from proximal to distal portions of bone. Images of the femoral region were obtained using a gamma camera 2-3 h after i.v. administration of 99mTc labeled MDP. Sixty patients (1-85 years old) were selected based on the criteria that their femoral images appeared normal and there was no history of limb disease. Radionuclide concentrations at the upper, middle, and lower regions of the femur were determined from the femoral scans by using an optical densitometer, and background corrected. Results were expressed as ratios of upper to middle, lower to middle, and upper to lower regions of the femur. The analysis showed that the lower to middle ratio declined with age.