High-Frequency Ultrasound: Description of Sacral Tissue Characteristics in Healthy Adults.

ABSTRACT

OBJECTIVES: The purpose of this study was to describe selected sacral tissue characteristics in a convenience sample of healthy volunteer subjects. DESIGN: Descriptive. SAMPLE AND SETTING: Fifty healthy volunteers in a clinical learning center in a school of nursing. METHODS: Sacral scans were obtained using a 20-MHz ultrasound scanning system in 3 positions prone and 60° and 90° side-lying from the back. The images were analyzed by software in the ultrasound program using quantitative parameters of dermal thickness and density (dermal median intensity and derived number of low-echogenic pixels to total pixels [LEPTP] ratio). RESULTS: In general, average values were as follows dermal thickness between 2.32 and 2.65 mm; median pixel intensity between 102 and 112; and the LEPTP ratio between 0.39 and 0.56. There were significant differences in sacral tissue characteristics between measures of thickness and dermal density (median intensity and LEPTP ratio) by subject side-lying position (60° and 90°) versus prone position, with all P values less than .0001. CONCLUSIONS: Overall, the ranges were consistent across measures of thickness and dermal density except for systematic differences between side-lying and prone positions. When comparing thickness, median intensity, or LEPTP ratio, it is important to report subject position. To best recognize tissue inflammation indicative of pressure injuries before surface changes are seen, it is useful to understand healthy high-frequency ultrasound sacral tissue characteristics. It is anticipated that quantitative assessment of dermal thickness, density, and LEPTP ratio could help identify individuals with incipient pressure injury.