Quantifying fibrosis in venous disease: mechanical properties of lipodermatosclerotic and healthy tissue.

OBJECTIVES: To quantify the mechanical properties of medioposterior bulk calf tissue in patients with lipodermatosclerotic venous-insufficient tissue and individuals with apparently healthy tissue using a novel ultrasound indentometry method, and to identify parameters with the potential for quantifying fibrosis in subsequent studies. DESIGN: 2-group, quasi-experimental design SETTING: Soft Tissue Mechanics Laboratory, University of Pittsburgh, Pittsburgh, PA PARTICIPANTS: 9 healthy and 9 venous-insufficient individuals aged 35 to 85 years INTERVENTIONS: Ultrasound indentometry and computed tomography (CT) of calf tissue MAIN OUTCOME MEASURES: Between group differences and associations among quasi-linear viscoelastic (QLV) tissue parameters and CT descriptors MAIN RESULTS: Established the accuracy, validity, and reliability of the QLV model and ultrasound indentometry method. Demonstrated a range of significant differences between the groups (P <.020 to P <.004) for selected QLV parameters. Also found significant correlations between CT measures of fibrosis and dermal thickness and QLV elastic measures (P <.034 to P <.005). CONCLUSION: Attempts to quantify fibrosis in lipodermatosclerosis have included histologic exams, palpation/pitting, durometer readings, and imaging techniques, but these efforts have failed to produce a clinically practical, noninvasive method. A novel ultrasound indentometry method was used to acquire in vivo data from which tissue parameters were derived. These data support the further development of ultrasound indentometry as a method to quantify fibrosis in venous disease.