Technetium scintigraphy (bone scan) was performed with IV injection of 800 MBq of Tc-99m MDP was performed followed by gallium scintigraphy with IV injection of 100 MBq of Ga-67 Citrate.
The technetium bone scan images demonstrate increased osteoblastic activity at the site of the bone surrounding the first metatarsophalangeal joint prosthesis. To differentiate possible infection from loosening, direct comparison is made to the gallium scintigraphy images. The site of faint increased gallium tracer uptake spatially corresponds well with the bone scan images, however the intensity (signal compared to background noise) is much fainter for gallium compared to technetium. This indicates that the increased osteoblastic activity on the technetium bone scan is consistent with prosthetic loosening, and underlying infection is unlikely.