Early detection of brain tumor response during local hydrogel based treatment using CEST MRI

Background:
CEST MRI is a non-invasive molecular imaging approach1, while APT has been applied to reveal molecular changes in brain tumors, such as tumor grading2 and differentiating tumor recurrence from tumor necrosis3. Here, based on our developed theranostic hydrogel, we would like to investigate the role of APT in the detection of tumor response to the local hydrogel-based treatment.
METHODS:
Liposomes (DPPC, cholesterol, DSPE-PEG2000) were prepared using thin-film hydration method. Gemcitabine solution was added then mixed with Methotrexate and alginate powder. The resulting mixture (MGLH) was mixed with calcium D-gluconate solution. The control hydrogel (LH) was fabricated without drugs. NOD-SCID mice (6-8 weeks, n=10) were injected with U-87 MG cell. After 2 weeks, hydrogel was injected next to the tumor and observed over 10 days. Using 3T Bruker Biospec system (Bruker, Germany), T2-weighted images and CEST were acquired (B1=0.8 uT; Tsat= 2 secs). 3.5 ppm were extracted for further analysis using LDA.
RESULTS AND DISCUSSION:
We observed reduction in both tumor size and signal at 3.5 ppm until day 10 in treatment group (Fig. A,C,D).