Adjuvant treatment using local drug delivery is applied in treating glioblastoma multiforme (GBM) after tumor resection. However, there are no non-invasive imaging techniques available for tracking the compositional changes of hydrogel-based drug treatment.

Methods: We developed Chemical Exchange Saturation Transfer Magnetic Resonance Imaging (CEST MRI) detectable and injectable liposomal hydrogel to monitor these events in vivo at 3T clinical field. Mechanical attributes of these hydrogels and their in vitro and in vivo CEST imaging properties were systematically studied.

Results: The MRI detectable hydrogels were capable of generating multiparametric readouts for monitoring specific components of the hydrogel matrix simultaneously and independently. Herein, we report, for the first time, CEST contrast at -3.4 ppm provides an estimated number of liposomes and CEST contrast at 5 ppm provides an estimated amount of encapsulated drug. CEST contrast decreased by 1.57% at 5 ppm, while the contrast at -3.4 ppm remained constant over 3 d in vivo, demonstrating different release kinetics of these components from the hydrogel matrix. Furthermore, histology analysis confirmed that the CEST contrast at -3.4 ppm was associated with liposome concentrations.

Conclusion: This multiparametric CEST imaging of individual compositional changes in liposomal hydrogels, formulated with clinical-grade materials at 3T and described in this study, has the potential to facilitate the refinement of adjuvant treatment for GBM.

使用局部药物递送的辅助治疗用于在肿瘤切除后治疗多形性胶质母细胞瘤（GBM）。但是，没有可用的非侵入性成像技术来跟踪基于水凝胶的药物治疗的成分变化。

方法：我们开发了可检测和可注射的脂质体水凝胶化学交换饱和转移磁共振成像（CEST MRI），以在3T临床领域体内监测这些事件。这些水凝胶的力学特性及其体外和体内CEST成像特性得到了系统的研究。

结果：MRI可检测的水凝胶能够生成多参数读数，以同时且独立地监测水凝胶基质的特定成分。在此，我们首次报道了-3.4 ppm的CEST对比提供了估计数量的脂质体，而5 ppm的CEST对比提供了估计数量的封装药物。CEST对比在5 ppm时降低了1.57％，而在-3 ppm时的对比在体内3 d内保持不变，表明这些成分从水凝胶基质释放的动力学不同。此外，组织学分析证实-3.4 ppm的CEST对比与脂质体浓度有关。

结论：本研究描述了由临床级材料在3T配制的脂质体水凝胶中各个成分变化的多参数CEST成像，具有促进GBM辅助治疗细化的潜力。