Comparative uptake of 67Ga and 99mTc MDP in rabbits with a benign noninfected bone lesion (fracture).
Mid-shaft fractures of the radius and ulna were produced in 3 to 4 kg New Zealand white rabbits and quantitative uptake of 99mTc MDP and 67Ga determined at 11, 18, 25, 32, 51, and 78 days following fracture. Two hundred microCi of 67Ga was administered 24 hours prior to sacrifice and 1.5 mCi 99mTc MDP 2 hours prior to sacrifice. Specific activity ratios (SARs) were determined between fracture and control sides for bone, muscle and skin. SARs for bone were surprisingly similar for 99mTc MDP and 67Ga, reaching peak values of 6.07 +/- 0.64 (99mTc 18 days); 6.58 +/- 0.90 (67Ga 32 days), subsequently decreasing to minimum values at 78 days postfracture (99mTc MDP 2.25 +/- 0.14; 67Ga 2.18 +/- 0.08). There was no statistically significant difference in SAR for 99mTc MDP vs. 67Ga in bone at any time after fracture. Whole sections of limb were resected on selected animals and activity ratios determined for these sections as a function of the contribution of activity from the various tissues in the volume of interest. Total activity ratios of 67Ga were lower than bone SARs as a result of the contribution of activity from muscle and skin. Thus the apparent lower activity ratios noted on 67Ga images compared with 99mTc MDP images in this fracture model were not due to differences in bone SARs but rather due to the higher soft tissue background activity contribution in the 67Ga images.
D000818:Animals; D050723:Fractures, Bone / Q000000981:diagnostic imaging*; D005710:Gallium Radioisotopes; D011817:Rabbits; D011877:Radionuclide Imaging; D011885:Radius Fractures / Q000000981:diagnostic imaging; D013669:Technetium Tc 99m Medronate; D014458:Ulna Fractures / Q000000981:diagnostic imaging
D005710:Gallium Radioisotopes; D013669:Technetium Tc 99m Medronate