Joint Program in Nuclear Medicine

Frostbite of the Digits

Andrew F. Childs, MD PhD
Scott Britz-Cunningham, MD

January 11.2004

Presentation

A 57 year-old male presented to the E.D. with the complaint of swollen and painful fingers (Figure 1 and Figure 2) following cocaine use and an evening outdoors working on his car. (Temperature -3 F, Windchill -30 F ). The orthopedics service requested plain films and a triple phase bone scan.

Imaging Findings

Plain film radiographs of left hand and right hand demonstrated diffuse soft tissue swelling of the digits bilaterally but no bony abnormalities.
Immediately following the IV administration of 20 mCi of Tc-99m MDP vascular phase images of the hands were obtained that showed no significant radiotracer activity in the mid and distal phalanges 2 through 5 bilaterally. Slightly increased perfusion was noted in the thumbs.
Tissue phase images in the palmar projection obtained at 20 minutes again demonstrated no significant radiotracer activity in the mid and distal 2nd through 5th digits. Moderately increased activity was again noted in the thumbs, most prominently in the proximal left thumb, and also in the region of the left fifth metacarpal. The images were repeated with cobalt markers to identify the location of the tips of the 3rd digits.
Delayed-phase images in the palmar projection were obtained at 4 hours with cobalt markers at the tips of digits 2 through 4 bilaterally. On these images radiotracer activity is seen in soft tissue and bony structures of the distal phalanges of both hands with the exception of the left fifth distal phalanx. Focally increased uptake is seen in the metacarpophalangeal joints, the interphalangeal joints of the thumbs, and in the metacarpophalangeal joints of the 2nd through 4th digits bilaterally. Slightly increased uptake is also noted in the left first carpometacarpal joint and in the radiocarpal joints bilaterally.

Diagnosis

The findings on vascular, blood flow and blood pool images are consistent with ischemic injury to the mid and distal 2nd through 5th phalanges bilaterally as the result of frostbite. The uptake pattern after 4 hours however is not suggestive of infarction, except for possibly the distal phalanx of the left hand, which is considered at risk.

Relatively increased delayed phase uptake in the thumbs predicts recovery of function in those digits. Other focal areas of increased uptake in small joints of the hands may represent the sequel of ischemic injury, but would be predictive of recovery of function in those regions. However these regions of focal uptake are nonspecific and given the patient’s age and history could represent degenerative or post-traumatic changes.

Given that bone scan findings tend to evolve over time, a follow up bone scan was recommended. However the patient declined.

Discussion

There are indications for triple phase bone scans in both the acute and chronic phases of frostbite injury.

In the acute setting (12-48 hours) there is evidence to suggest that fibrinolytic therapy may decrease the degree of tissue necrosis if no blood flow is demonstrated on vascular or tissue phase images of a bone scan (1). A prominent mechanism of tissue injury in frostbite is thought to involve direct endothelial injury with resulting hemoconcentration, increased viscosity and thrombus formation. Although somewhat controversial, some clinicians have incorporated thrombolysis into their treatment regimen following rapid re-warming if vascular and tissue phase bone scan images demonstrate no activity in the affected extremity(2,3).

Bone scans are also useful during the chronic phase of injury (2 days to weeks). Bone scans obtained between days 2 and 4 have been found to provide accurate prognostic information on the future evolution of lesions (4-6). Together with a second scan between days 7 and 8 these studies can be used to accurately establish the limits of amputation. In the setting of severe sepsis an emergent bone scan can provide the only objective basis for determining the limits of amputation (4,7).

References

1. Skolnick A, Early Data Suggest Clot-Dissolving Drug May Help Save Frostbitten Limbs from Amputation. JAMA, Vol 267, No. 15. April 15, 1992.

2. Mills WJ Jr, Frostbite: A method of management including rapid thawing. Northwest Med 65:119-125, 1966.

3. House JH, Fidler MO, Frostbite of the Hand. In Green’s Operative Hand Surgery, 4th ed. New York: Churchill Livingstone, 1999 Pp 2061-7.

4. Cauchy, E, et al, The Value of Technetium 99 Scintigraphy in the Prognosis of Amputation in Severe Frostbite Injuries of the Extremities: A Retrospective Study of 92 Severe Frostbite Injuries. J Hand Surg 2000;25A:969-978.

5. Cauchy, E, et al, The role of bone scanning in severe frostbite of the extremities: a retrospective study of 88 cases. Eur J Nucl Med (2000) 27:497-502.

6. Mehta, R, et al, Frostbite Injury: Prediction of Tissue Viability with Triple-Phase Bone Scanning. Radiology 1989; 170: 511-514.

7. Bhatnagar A, et al, Diagnosis, characterization and evaluation of treatment response of frostbite using pertechnetate scintigraphy: a prospective study. Eur J Nucl Med Feb (2002) 29: 170-175.

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J. Anthony Parker, MD PhD, Tony_Parker@CareGroup.Harvard.edu