Ultrasonic analysis of acute thermal and radiation injury—A pilot study

Medical injury from a terrorist event (IND, RDD) is likely to involve both radiation damage and thermal trauma (combined injury). A high-frequency ultrasound technique has previously been developed to function as a clinical tool to distinguish partial-thickness from full-thickness thermal burns in a porcine model and the method was later extended for use in clinical burn units. In a traditional clinical setting, the technique has shown sufficient sensitivity to quantitate extension of a partial-thickness burn to a full-thickness burn through cutaneous infection. The ultrasound method has been extended in a pilot study to analyze radiation-induced cutaneous injury. Analysis of radiation-induced skin injury is more difficult than for thermal injury. However, further development of the method has shown a time-dependent response curve for the scattered ultrasound signal after irradiation of Wistar rat tails to 40 Gy with a 120 KeV X-ray spectrum. Statistically significant changes (p<0.05)(p<0.05) in the magnitude of the reflected ultrasound spectrum have been noted less than 6 h-post-irradiation. The scattered intensity response curve peaks near the appearance of the first clinical sign (erythema) at 12 days post-irradiation. The mechanism of ultrasound sensitivity appears to involve changes in the tissue acoustic impedance post-irradiation possibly due to hyperemia, vascular damage and leakage. Because of the penetrating power and resolution of recent ultrasound equipment, this technique is expected to be extendable to analysis of irradiated deep organs, of large- and medium-size blood vessels, and to possible analysis of combined injury.