Intermittent pneumatic compression: effect on the lower limb bone uptake of Tc99m MDP

Introduction: Venous compression of the lower limbs will obstruct outflow through deep and superficial veins, yet inflow will continue without continual swelling of the limb. It is hypothesized that venous channels in the long bones will act as collateral channels to restore outflow, and therefore general blood flow through bone will increase. Such a hemodynamic change should affect the uptake of radiopharmaceuticals by the bone. The purpose of this study therefore was to determine whether bone uptake in the lower limb would be affected by intermittent venous compression, with any mechanism. Materials and Methods: The effect of intermittent pneumatic compression of the thigh and calf on uptake of 99Tcm methylene diphosphonate (MDP) was studied in twenty-four patients. All were undergoing routine bone imaging for medical conditions that were not focussed on their lower limbs, and received 1 hour of the therapy at 60 mmHg on one limb only, after injection of the radiopharmaceutical. Three hours after injection the relative difference in uptake (net counts per pixel) between the two limbs was calculated. Results: The median differences in uptake in the intermittently compressed limb, compared to the contralateral limb, were +7.6% (interquartile range +3.9% to +16.0%, p<0.0005 [Wilcoxon]) for the anterior aspect of the femur; +11.7% (interquartile range +4.3% to +22.2%, p<0.0005) posterior, femur; +10.5% (interquartile range +6.5% to +13.8%, p<0.0005) anterior, tibia; +10.6% (interquartile range +5.5% to +17.6%, p<0.0005) posterior, tibia. Conclusions: Intermittent pneumatic compression clearly increased the uptake of 99Tcm MDP in long bones by probably affected the blood flowing through the bones. (authors)