Multimodal Photoacoustic/Ultrasound Imaging System for Longitudinal Assessment of Keloid Treatment

To evaluate the feasibility of using a multimodal photoacoustic/ultrasound imaging system for longitudinal monitoring of keloid lesions during intralesional therapy, and to assess its potential as an objective tool for treatment follow-up.

A patient with 5 keloids underwent serial imaging at 5 time points during intralesional injections of betamethasone and 5-fluorouracil. Clinical assessment was performed using the Vancouver Scar Scale (VSS). A multimodal photoacoustic/ultrasound imaging system which integrates different techniques was used to monitor structural, vascular, oxygenation, and elasticity changes during treatment. Structural parameters were assessed by grayscale ultrasound (GSUS), vascularity was evaluated by ultrasonographic microvascular angiography (UMA) and photoacoustic imaging (PAI), while oxygen saturation (SO₂) provided by PAI, and elasticity was measured via elastography.

VSS scores decreased significantly from 7.6 ± 2.3 at baseline to 2.2 ± 1.6 at T4 (p = .001), with improvements in pigmentation (p = .003), pliability (p = .009), and vascularity (p = .004). GSUS showed a reduction in total lesion thickness from 26.8 ± 10.5 mm to 8.0 ± 4.5 mm (p = .006), along with significant decreases in lesion lengths (p < .05). PAI demonstrated a decline in blood flow signals and an increase in SO₂ levels in most lesions. UMA and PAI revealed reduced vascular density during treatment. Early-stage increases in stiffness were observed, but subsequent measurements became unfeasible as the lesions thinned.

A multimodal PA/US imaging system provides comprehensive and noninvasive assessment of both structural and functional changes in keloids during treatment. This longitudinal study suggests its potential as a valuable tool for objective and dynamic monitoring of therapeutic response in scar management.