MR-based skull parametric modeling for blood-brain barrier opening in non-human primates

Area of Science:

• Medical Imaging
• Biomedical Engineering
• Neurosurgery

Background:

• Transcranial focused ultrasound (FUS) requires CT-based planning, involving ionizing radiation.
• Zero echo time (ZTE) MRI provides safe bone imaging for planning blood-brain barrier opening (BBBO).
• Non-human primates (NHPs) are crucial models for FUS and BBBO research.

Purpose of the Study:

• To develop and validate a ZTE-to-CT skull modeling method for non-ionizing FUS/BBBO planning in NHPs.
• To assess the accuracy of ZTE-based (pseudo-CT/pCT) simulations compared to CT-based simulations.

Main Methods:

• A linear-regression method was used to establish the ZTE-to-CT skull relationship in six NHP skulls.
• Ex-vivo and in-vivo simulations were performed comparing ZTE-based (pCT) and CT-based planning.
• Key simulation parameters including focal volume, attenuation, and shifts were analyzed.

Main Results:

• Ex-vivo simulations showed minimal differences between pCT and CT for focal volume, attenuation, and shifts.
• In-vivo planning simulations demonstrated comparable results between pCT and CT for focal parameters and BBBO volume prediction.
• The ZTE-to-CT method accurately predicted sonicated skull thickness and Skull Density Ratio.

Conclusions:

• The feasibility of a ZTE-to-CT skull modeling method for NHP BBBO planning is demonstrated.
• This approach offers a fully non-ionizing planning technique for transcranial FUS applications.
• ZTE MRI is a viable alternative to CT for radiation-free FUS planning in preclinical research.