Department of Spine Surgery, The Third Affiliated Hospital of Sun Yat-Sen University, China; Department of Biomedical Engineering, Faculty of Engineering, The Hong Kong Polytechnic University, Hong Kong.
Department of Biomedical Engineering, Faculty of Engineering, The Hong Kong Polytechnic University, Hong Kong.
Prog Biophys Mol Biol. 2019 Nov;148:12-20. doi: 10.1016/j.pbiomolbio.2018.03.009. Epub 2018 Mar 28.
This pilot study aimed to investigate the feasibility of non-invasively assessing synovial tissue hypoxia in vivo using photoacoustic (PA) imaging in a post-traumatic osteoarthritis model and explore its correlation with OA severity.
The three-dimensional vasculature structure and oxygenation level of synovial tissues of destabilization of the medial meniscus (DMM)-induced osteoarthritis (OA) mice were longitudinally monitored using PA imaging. Vascular volume/tissue volume (%) and tissue oxygen saturation (sO) were validated against results obtained by established Power Doppler (PD) imaging and dynamic changes of inhaled O concentration respectively. PA changes were correlated with the histological grading of cartilage damages.
PA-measurements of vascularity and sO demonstrated a strong correlation with localized blood flow detected by PD imaging (r = 0.506, p < 0.001) and inhaled O concentration. DMM knees exhibited much more vascularity in synovial tissue at 4 months after surgery (median 11.3%, IQR: 10.7-15.5%) than the intact knees at time zero (median:5.1%, IQR:3.8-6.8%, p < 0.001) as well as the sham-operated knees (median: 4%, IQR: 3.75-5.45%, p = 0.017). Paradoxically, synovial tissue sO was significantly lower in DDM knees (median: 37.7%, IQR: 36.4-40.6%) than both the intact (47.1%, IQR: 41.9-49.8% p = 0.001) and sham-operated knees (45.1% IQR: 45.1-52.4%, p = 0.017). The PA-detected synovial tissue hypoxia correlated with the severity of cartilage loss in DMM mice (rho = -0.597, p = 0.031).
Here, we demonstrated PA imaging can be implemented for non-invasive imaging of the synovial tissue. Under PA imaging, synovitis in OA was characterized by increased angiogenesis and synovial tissue hypoxia; the latter was associated with the severity of OA.
本研究旨在通过光声（PA）成像技术在创伤性骨关节炎模型中探索无创评估滑膜组织缺氧的可行性，并探讨其与骨关节炎严重程度的相关性。
通过 PA 成像对内侧半月板不稳定（DMM）诱导的骨关节炎（OA）小鼠的滑膜组织三维血管结构和氧合水平进行纵向监测。血管体积/组织体积（%）和组织氧饱和度（sO）分别通过与已建立的功率多普勒（PD）成像结果和吸入 O 浓度的动态变化进行验证。PA 变化与软骨损伤的组织学分级相关。
PA 测量的血管化程度和 sO 与 PD 成像检测到的局部血流（r=0.506，p<0.001）和吸入 O 浓度具有很强的相关性。DMM 膝关节术后 4 个月的滑膜组织血管化程度明显高于零时的正常膝关节（中位数 11.3%，IQR：10.7-15.5%，p<0.001），也高于假手术膝关节（中位数：4%，IQR：3.75-5.45%，p=0.017）。矛盾的是，DMM 膝关节的滑膜组织 sO 明显低于正常膝关节（中位数：37.7%，IQR：36.4-40.6%，p=0.001）和假手术膝关节（中位数：47.1%，IQR：41.9-49.8%，p=0.001）。PA 检测到的滑膜组织缺氧与 DMM 小鼠软骨丢失的严重程度相关（rho=-0.597，p=0.031）。
本研究证明了 PA 成像可用于滑膜组织的无创成像。在 PA 成像下，OA 滑膜炎的特征是血管生成增加和滑膜组织缺氧；后者与 OA 的严重程度相关。
