Preclinical Model of Optical Coherence Tomography for High-Resolution Deep-Brain Imaging for Laser Ablation

Take-Away Points

• ■ Major Focus: Preclinical in vivo imaging of the deep brain using an optical coherence tomography (OCT) needle for tissue visualization and laser ablation.

• ■ Key Result: OCT imaging in a murine model was capable of producing high-resolution images of the deep brain before and after laser ablation at a resolution of 1.7 μm (axial) × 5.7 μm (lateral).

• ■ Impact: Development of this tool for deep-brain imaging and ablation would allow for more precise and real-time imaging during ablation procedures in clinical practice.

High-resolution three-dimensional imaging would be beneficial for viewing solid organs for planning and monitoring of cancer ablation therapies. Typical laser ablation procedures require MRI to determine where the target lesion is located, to confirm placement of the ablation probe, and to observe the effect of ablation during the procedure. For sensitive imaging areas, such as the brain, time needed for MRI to verify probe positioning and possible repositioning increases risk of injury to the patient. Together, a real-time high-resolution imaging technique that could overcome these issues would be beneficial for planning and monitoring of solid organ ablation procedures.

In this study, Yuan et al assembled an 800-nm optical coherence tomography (OCT) imaging needle that was capable of high-resolution imaging (1.7 μm [axial] × 5.7 μm [lateral]). Additionally, this needle was equipped with a near-infrared laser for tissue ablation. For their first proof-of-concept study, the group imaged brain tissue in mice by introducing the microneedle through two burr holes made in the skull. Three-dimensional, color-coded images were generated by imaging a 4.5-mm-long cylindrical volume in the deep brain. Images detected even filament bundles in deep brain tissues. The authors also successfully imaged brain tumors marked with green fluorescent protein. Images from both normal and malignant brain tissue showed high concordance to histology.

To demonstrate potential imaging laser ablation procedures in patients, the authors imaged mouse brains before and immediately after laser ablation. By assessing volumetric OCT brain images, the authors verified successful laser ablation of the target volume demonstrated by histology. Taken together, the authors show exciting first steps toward developing an OCT microneedle for real-time high-resolution clinical imaging and precision laser ablation of solid organ tumors, such as glioblastomas.

Highlighted Article

Yuan W, Chen D, Sarabia-Estrada R, et al. Theranostic OCT microneedle for fast ultrahigh-resolution deep-brain imaging and efficient laser ablation in vivo. Sci Adv 2020;6(15):eaaz9664. doi: 10.1126/sciadv.aaz9664