A Feasibility Study of Multimodal Optical Coherence Tomography Angiography and Elastography for Assessing Foot...

The foot is regularly exposed to mechanical loading during daily activities. Repeated loading can affect both microvascular and mechanical properties of foot tissue. Optical coherence tomography angiography (OCTA) and optical coherence elastography (OCE) provide non-invasive methods for assessing these changes. This feasibility study evaluated combined OCTA and OCE imaging for measuring vascular and mechanical responses in healthy foot skin following repeated loading in 10 healthy volunteers. The dorsal and plantar regions of the foot were imaged using a portable swept-source OCT system. Baseline measurements were acquired first, followed by three repeated loading cycles (C1, C2, and C3). For each cycle, the same force was applied for 30 s. The force differed between participants according to individual tolerance and averaged approximately 25 N across the experiment. OCTA and OCE acquisition began approximately 3 s after force release to observe changes in vascular and mechanical parameters following repeated loading. In the plantar region, vessel skeleton density (VSD) showed a significant overall difference between loading conditions (p = 0.006). Young's modulus showed significant overall differences in both the dorsal and plantar regions (both p < 0.001). Relative to baseline, the dorsal Young's modulus was 22.9%, 32.3%, and 39.0% higher following C1, C2, and C3, respectively. The corresponding values in the plantar region were 18.1%, 29.2%, and 39.0% higher. Repeated-measures ANOVA identified significant loading effects for VSD, vessel area density (VAD), and Young's modulus, together with a significant region effect for VSD. These findings demonstrate the feasibility of combined OCTA and OCE imaging for assessing vascular and mechanical responses in healthy foot tissue following repeated loading. This method may support future studies of foot tissue response in populations with altered microcirculation or tissue mechanics, including people at risk of diabetic foot complications.