Blood flow and bone uptake of^99mTc‐labeled methylene diphosphonate

Abstract

In mature dogs with comparable levels of bone remodeling, we produced either increased (with adenosine triphosphate) or decreased (with epinephrine) blood flow to one hindlimb. In 13 dogs (five control, four with increased flow, and four with decreased flow), we compared uptake, at 3 h after injection of radiolabeled diphosphonate in the mid-tibia, with blood flow as determined by microspheres. Blood flow was determined with 85Sr-labeled microspheres, and determination of uptake of 99mTc methylene diphosphonate (99mTc-MDP) was by a gamma detector. There was a linear relationship between changes in diphosphonate uptake and changes in blood flow at decreased and normal flows; however, at high flows the relationship was nonproportional, indicating a disproportionately slower increase in 99mTc-MDP uptake with increasing blood flow. In six dogs an initial 1-h uptake curve of 99mTc-MDP was determined in both control and experimental limbs under states of increased and decreased blood flow. The 30-min uptake value, 60-min uptake value, area under the curve, and the slope of the curve were related to flow as determined by microspheres. The data are consistent with the hypothesis that deposition of bone-concentrating isotopes such as 99mTc-MDP is partly controlled by blood flow; at supranormal and normal flows tracer uptake is closely related to blood flow, but at supranormal flow rates it is not and appears to be diffusion limited.

Effects of mechanical loading on the tissues of the rabbit knee

“…This suggests that uptake occurs at sites of both bone resorption and bone formation, but that it is greater where bone is being resorbed. Linking 9 9 m T~ uptake more to resorption than to formation is in accord with its association with increased blood flow (6,32); proliferation of capillaries occurs during the earliest stages of bone remodeling.…”

Three‐phase [99mTc]diphosphonate scintimetry in septic and nonseptic arthritis of the immature knee: An experimental investigation in dogs

“…The uptake mechanism of bone seeking radionuclides has been subjected to thorough investigation (5,7,8,13,(22)(23)(24)(25)(26)(27)(28). Apparently, the target for bone uptake of diphosphonate complexes is hydroxyap-atite crystal surfaces, (5,8,26), especially in areas with high mineralization activity, e.g., bone in the process of repair (23) or growth such as the metaphyseal calcification layer of growth plates and the epiphyseal osteochondral junction (5).…”

“…Imaging of both im-mediate and delayed tracer uptake constitutes [99"Tc]DPD three-phase scintigraphy, which has proved especially advantageous in early detection of infantile osteomyelitis (10, 16,17). The delayed bony uptake of [99"Tc]DPD depends both on rate of tracer delivery by blood (24,25,27) and bone metabolism (5,8,26), although the immediate dynamic uptake of [99"Tc]DPD following an intravenous (i.v.) bolus injection correlates well with bone perfusion (22,23).…”

EFFECTS OF ACEPROMAZINE ON THREE‐PHASE99mTc‐MDP BONE IMAGING IN 11 HORSES

“…In conditions in which blood flow is low, increasing the blood flow will increase the radiopharmaceutical uptake. In conditions in which blood flow is higher, increasing further the blood flow will not increase radiopharmaceutical uptake proportionally 29 . In contrast, a positive correlation between perfusion and bone uptake has been found after exercise 7 .…”

“…In conditions in which blood flow is higher, increasing further the blood flow will not increase radiopharmaceutical uptake proportionally. 29 In contrast, a positive correlation between perfusion and bone uptake has been found after exercise. 7 However care should be taken in comparing these two different populations of animals.…”