Injectable hydrogels are being widely explored for treatment after myocardial infarction (MI) through mechanical bulking or the delivery of therapeutics. Despite this interest, there have been few approaches to image hydrogels upon injection to identify their location, volume, and pattern of delivery, features that are important to understand toward clinical translation. Using a hyaluronic acid (HA) hydrogel as an example, the aim of this study is to introduce radiopacity to hydrogels by encapsulating a clinically used contrast agent (Omnipaque Iohexol, GE Healthcare) for imaging upon placement in the myocardium. Specifically, iohexol is encapsulated into shear‐thinning and self‐healing hydrogels formed through the mixing of HA‐hydrazide and HA‐aldehyde. Upon examination of a range of iohexol concentrations, a concentration of 100 mg mL⁻¹ iohexol is deemed optimal based on the greatest contrast, while maintaining hydrogel mechanical properties and acceptable injection forces. In an acute porcine model of MI, hybrid single‐photon emission computed tomography/computed tomography (SPECT/CT) perfusion imaging is performed immediately and 3–4 days after hydrogel delivery to assess radiopacity and verify the hydrogel location within the perfusion defect. Hybrid SPECT/CT imaging demonstrates excellent radiopacity of the hydrogel within the perfusion defect immediately after intramyocardial hydrogel injection, demonstrating the feasibility of this method for short‐term noninvasive hydrogel monitoring.

中文翻译：

---

使用 SPECT/CT 对注入心肌的可注射水凝胶进行成像。

人们正在广泛探索可注射水凝胶通过机械膨胀或递送治疗剂来治疗心肌梗塞（MI）后的情况。尽管有这样的兴趣，但目前还没有什么方法可以在注射时对水凝胶进行成像，以确定其位置、体积和输送模式，这些特征对于理解临床转化非常重要。以透明质酸 (HA) 水凝胶为例，本研究的目的是通过封装临床使用的造影剂（Omnipaque Iohexol，GE Healthcare）来将射线不透性引入水凝胶中，以便在放置在心肌中时进行成像。具体来说，碘海醇被封装到通过HA-酰肼和HA-醛混合形成的剪切稀化和自修复水凝胶中。在检查一系列碘海醇浓度时，基于最大对比度， 100 mg mL ^{-1碘海醇的浓度被认为是最佳的，同时保持水凝胶机械性能和可接受的注射力。}在急性心肌梗死猪模型中，在水凝胶输送后立即和 3-4 天进行混合单光子发射计算机断层扫描/计算机断层扫描 (SPECT/CT) 灌注成像，以评估射线不透性并验证水凝胶在灌注缺陷内的位置。混合 SPECT/CT 成像显示，心肌内注射水凝胶后，灌注缺损内的水凝胶具有出色的射线不透性，证明了该方法用于短期无创水凝胶监测的可行性。