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Localization of Transcranial Targets for Photoacoustic-Guided Endonasal Surgeries
Muyinatu A Lediju Bell1, Anastasia K Ostrowski2, Ke Li1
1The Johns Hopkins University, Baltimore, MD USA.
Abstract:
Neurosurgeries to remove pituitary tumors using the endonasal, transsphenoidal approach often incur the risk of patient death caused by injury to the carotid arteries hidden by surrounding sphenoid bone. To avoid this risk, we propose intraoperative photoacoustic vessel visualization with an optical fiber attached to the surgical tool and an external ultrasound transducer placed on the temple. Vessel detection accuracy is limited by acoustic propagation properties, which were investigated with k-Wave simulations. In a two-layer model of temporal bone (3200 m/s sound speed, 1-4 mm thickness) and surrounding tissues, the localization error was ≤2 mm in the tranducer's axial dimension, while temporal bone curvature further degraded target localization. Phantom experiments revealed that multiple image targets (e.g. sphenoid bone and vessels) can be visualized, particularly with coherence-based beamforming, to determine tool-to-vessel proximity despite expected localization errors. In addition, the potential flexibility of the fiber position relative to the transducer and vessel was elucidated.
Insights
This study introduces photoacoustic imaging to visualize carotid arteries during pituitary tumor surgery, enhancing safety. The technique helps surgeons avoid critical vessel injury by showing tool proximity to arteries, reducing surgical risks.
Area of Science:
- Biomedical Optics
- Medical Imaging
- Surgical Navigation
Background:
- Endonasal, transsphenoidal pituitary tumor removal risks carotid artery injury.
- The sphenoid bone obscures critical vasculature, posing a significant surgical hazard.
- Accurate intraoperative visualization of deep-seated vessels is crucial for patient safety.
Purpose of the Study:
- To develop and evaluate an intraoperative photoacoustic vessel visualization system.
- To assess the feasibility of using optical fibers and ultrasound for real-time vessel imaging during neurosurgery.
- To investigate methods for improving vessel detection accuracy in the presence of bone and anatomical variations.
Main Methods:
- Simulated acoustic propagation using k-Wave in multi-layered models.
- Phantom experiments with realistic tissue and bone phantoms.
- Utilized an optical fiber attached to a surgical tool and an external temple-placed ultrasound transducer.
- Employed coherence-based beamforming for enhanced target visualization.
Main Results:
- k-Wave simulations characterized acoustic propagation and localization errors (≤2 mm axial error in temporal bone model).
- Temporal bone curvature was identified as a factor degrading localization accuracy.
- Phantom experiments successfully visualized multiple targets, including bone and vessels.
- Coherence-based beamforming improved the determination of tool-to-vessel proximity despite localization uncertainties.
Conclusions:
- Intraoperative photoacoustic imaging offers a promising method for visualizing critical vasculature during endonasal neurosurgery.
- The proposed system can help mitigate the risk of carotid artery injury by providing real-time proximity information.
- Further investigation into optimizing imaging parameters and accounting for anatomical variability is warranted.
