Department of NanoEngineering, University of California San Diego, La Jolla, California, 92093.
Material Science and Engineering Program, University of California San Diego, La Jolla, California, 92093.
Wound Repair Regen. 2019 Sep;27(5):488-496. doi: 10.1111/wrr.12751. Epub 2019 Jul 26.
Ulcers including pressure ulcers and diabetic foot ulcers damage the skin and underlying tissue in people with compromised blood circulation. They are classified into four stages of severity and span from mild reddening of the skin to tissue damage and muscle/bone infections. Here, we used photoacoustic imaging as a noninvasive method for detecting early tissue damage that cannot be visually observed while also staging the disease using quantitative image analysis. We used a mouse model of pressure ulcers by implanting subdermal magnets in the dorsal flank and periodically applying an external magnet to the healed implant site. The magnet-induced pressure was applied in cycles, and the extent of ulceration was dictated by the number of cycles. We used both laser- and light-emitting diode (LED)-based photoacoustic imaging tools with 690 nm excitation to evaluate the change in photoacoustic signal and depth of injury. Using laser-based photoacoustic imaging system, we found a 4.4-fold increase in the photoacoustic intensity in stage I vs. baseline (no pressure). We also evaluated the depth of injury using photoacoustics. We measured a photoacoustic ulcer depth of 0.38 ± 0.09 mm, 0.74 ± 0.11 mm, 1.63 ± 0.4 mm, and 2.7 ± 0.31 mm (n = 4) for stages I-IV, respectively. The photoacoustic depth differences between each stage were significant (p < 0.05). We also used an LED-based photoacoustic imaging system to detect early stage (stage I) pressure ulcers and observed a 2.5-fold increase in photoacoustic signal. Importantly, we confirmed the capacity of this technique to detect dysregulated skin even before stage I ulcers have erupted. We also observed significant changes in photoacoustic intensity during healing suggesting that this approach can monitor therapy. These findings were confirmed with histology. These results suggest that this photoacoustic-based approach might have clinical value for monitoring skin diseases including pressure ulcers.
溃疡，包括压疮和糖尿病足溃疡，会损害血液循环受损人群的皮肤和皮下组织。它们分为四个严重程度阶段，从皮肤轻度变红到组织损伤和肌肉/骨骼感染不等。在这里，我们使用光声成象作为一种非侵入性方法来检测早期肉眼无法观察到的组织损伤，同时使用定量图像分析对疾病进行分期。我们使用在背部侧腹植入皮下磁铁并定期将外部磁铁应用于愈合植入部位的小鼠压疮模型。磁压呈周期性施加，溃疡的严重程度由施加的周期数决定。我们使用基于激光和发光二极管 (LED) 的光声成像工具，以 690nm 激发，来评估光声信号和损伤深度的变化。使用基于激光的光声成像系统，我们发现与基线（无压力）相比，I 期的光声强度增加了 4.4 倍。我们还使用光声技术评估了损伤深度。我们测量了光声溃疡深度为 0.38±0.09mm、0.74±0.11mm、1.63±0.4mm 和 2.7±0.31mm（n=4），分别为 I-IV 期。每个阶段之间的光声深度差异均具有统计学意义（p<0.05）。我们还使用基于 LED 的光声成像系统来检测早期（I 期）压疮，观察到光声信号增加了 2.5 倍。重要的是，我们证实了该技术即使在 I 期溃疡出现之前也能够检测到失调的皮肤。我们还观察到愈合过程中光声强度的显著变化，这表明该方法可以监测治疗效果。这些发现与组织学结果一致。这些结果表明，这种基于光声的方法可能对监测包括压疮在内的皮肤病具有临床价值。
