Figure 9d.

Fourth-degree frostbite of the feet in a 46-year-old man with a history of congestive heart failure. (a) Dorsal photographs show bilateral toe gangrene, which is more extensive in the right foot. (b–d) Multiphase ^99mTc-MDP bone scintigraphic images with toe and heel markers show absent tracer uptake beyond the right midfoot in the plantar blood flow phase at 100 seconds (b), soft-tissue phase (c), and 5.5-hour delayed phase (d). Note absent tracer uptake in the left fourth and fifth toes (arrowhead in c) on the soft-tissue phase image. Also note the lack of osseous uptake on the delayed phase image in d, a finding attributed to a combination of impaired local delivery of tracer and the patient’s low cardiac output. Late delayed phase images should be obtained 18–24 hours after tracer injection if osseous uptake is absent on initial delayed phase images. (e) Fused SPECT/CT image of the feet obtained 24 hours after tracer administration delineates the level of tracer cutoff in the right foot as just distal to the tarsometatarsal joints. (f, g) Three-dimensional lateral (f) and two-dimensional dorsoplantar (g) SPECT/CT images show that tracer uptake is also absent in the left fourth and fifth toes (arrowheads). The patient subsequently underwent a right below-the-knee amputation and left fourth and fifth toe amputations.