MR temperature imaging of nanoshell mediated laser ablation

Area of Science:

• Biomedical Engineering
• Nanotechnology
• Oncology

Background:

• Minimally invasive thermal therapies, particularly laser ablation, are under active clinical investigation.
• Gold nanoshells (AuNS) offer tunable light absorption for enhanced, targeted tumor heating.
• Targeted heating may improve conformal tumor ablation and spare surrounding healthy tissue.

Purpose of the Study:

• To investigate the efficacy of gold nanoshells (AuNS) in enhancing minimally invasive thermal therapy for prostate cancer.
• To characterize nanoparticle-mediated heating in a preclinical xenograft model using MR temperature imaging (MRTI).

Main Methods:

• Utilized a PC-3 prostate cancer xenograft model in mice.
• Administered AuNS intravenously and monitored their passive accumulation in tumors.
• Applied 808 nm laser ablation (4 W/cm², 180 sec) to tumors with and without AuNS.
• Employed MR temperature imaging (MRTI) for real-time, spatiotemporal temperature monitoring.

Main Results:

• Microscopy confirmed AuNS (140-150 nm) accumulation near tumor microvasculature.
• MRTI showed a significant temperature increase (21 ± 7°C) in AuNS-treated tumors compared to controls (p < 0.001).
• Histopathology revealed visible tumor damage correlating with higher temperature distribution in AuNS-treated tumors.

Conclusions:

• Intravenously injected AuNS effectively convert tumor vasculature into a heating source for nanoparticle-mediated ablation.
• This approach enables potent tumor ablation at laser power levels that minimize damage to normal tissues.
• Combined with MRTI, AuNS-mediated therapy holds promise for conformal interstitial laser ablations.