The role of bone scanning in severe frostbite of the extremities: a retrospective study of 88 cases

Abstract

We performed a retrospective study of the results of two-phase technetium-99m hydroxymethylene diphosphonate bone scans in 88 patients with severe frostbite of the extremities. All patients were evaluated within 48 h after rewarming and all underwent a first bone scan (BS1) within 5 days after rewarming (median, day 2) (group 1). An excellent correlation was found between absence of tracer uptake in the phalanges and later amputation; this correlation was especially strong during the bone phase of the scans (specificity = 0.99, sensitivity = 0.96, positive predictive value = 0.92). Normal or high uptake in the phalanges was a reliable indicator of ultimate healing (negative predictive value = 0.99). The sensitivity of the examination was enhanced by performing a second scan (BS2) more than 5 days (median, day 8) after rewarming (group 2, n = 36). A comparative analysis of BS1 and BS2 demonstrated that some of the lesions continued to evolve between day 2 and day 8. This suggests that the lesions could still be modified during this period. On the basis of the findings it is recommended that bone scan be performed close to day 2 in all patients who present with lesions extending proximally to include the entirety of one or more phalanges. In the case of severe sepsis, the results of the first bone scan, BS1, can serve as an indication for emergency amputation. BS2 should be performed close to day 8 only if there is an area of low or absent uptake on BS1. It is concluded that scintigraphy is an excellent means of evaluating patients with severe frostbite of the extremities: as early as day 2 after the injury it can indicate whether amputation is necessary, and between days 2 and 8 it provides valuable information on the efficacy of treatment.

Frostbite: Spectrum of Imaging Findings and Guidelines for Management

“…The scan should be performed 2-4 days after the original injury, or after angiography is completed in patients who undergo intra-arterial thrombolysis (34)(35)(36)(37)(38). A repeat scan at 7-10 days after injury can then be performed as warranted before surgical resection to evaluate interval change in areas of questionable uptake identified at the prior scan (34,35).…”

“…The scan should be performed 2-4 days after the original injury, or after angiography is completed in patients who undergo intra-arterial thrombolysis (34)(35)(36)(37)(38). A repeat scan at 7-10 days after injury can then be performed as warranted before surgical resection to evaluate interval change in areas of questionable uptake identified at the prior scan (34,35). By using this approach, the approximate level of amputation can be accurately predicted in up to 84% of cases at the initial scan, weeks before the demarcation of viable and nonviable tissue is clearly apparent at physical examination (34,36,39).…”

“…By using this approach, the approximate level of amputation can be accurately predicted in up to 84% of cases at the initial scan, weeks before the demarcation of viable and nonviable tissue is clearly apparent at physical examination (34,36,39). Specificity increases at subsequent scanning as ongoing healing and necrosis resolve areas of questionable uptake (34,35). If feasible, débridement of blisters should be undertaken before scanning to limit false-positive results caused by pooling of tracer within blisters during the soft-tissue phase (34,35).…”

“…Specificity increases at subsequent scanning as ongoing healing and necrosis resolve areas of questionable uptake (34,35). If feasible, débridement of blisters should be undertaken before scanning to limit false-positive results caused by pooling of tracer within blisters during the soft-tissue phase (34,35). However, the optimal management of frostbite-related blisters (especially hemorrhagic blisters) is controversial and is best left to the treatment team's discretion (11).…”

“…However, the optimal management of frostbite-related blisters (especially hemorrhagic blisters) is controversial and is best left to the treatment team's discretion (11). The first imaging study can provide all information necessary for surgical excision in patients with severe injuries who develop infection or sepsis or who cannot wait for subsequent imaging (34,35).…”