A 72-year-old patient with type 2 diabetes mellitus underwent 18F-FDG PET/CT for diabetic foot infection. No increased focal uptake was seen. 18F-FDG uptake was absent in the second, third, and fourth toes of the right foot. Angiography demonstrated severe stenosis in the proximal anterior tibial artery and segmental stenosis on the posterior tibial artery. The patient was diagnosed as having dry gangrene of the second to fourth toes of the right foot due to ischemia. He underwent a selective amputation because of the lack of revascularization possibilities.