A Neural Implant Design Toolbox for Nonhuman Primates

Summary

This paper outlines automated processes for nonhuman primate neurosurgical planning based on magnetic resonance imaging (MRI) scans. These techniques use procedural steps in programming and design platforms to support customized implant design for NHPs. The validity of each component can then be confirmed using three-dimensional (3D) printed life-size anatomical models.

Abstract

This paper describes an in-house method of 3D brain and skull modeling from magnetic resonance imaging (MRI) tailored for nonhuman primate (NHP) neurosurgical planning. This automated, computational software-based technique provides an efficient way of extracting brain and skull features from MRI files as opposed to traditional manual extraction techniques using imaging software. Furthermore, the procedure provides a method for visualizing the brain and craniotomized skull together for intuitive, virtual surgical planning. This generates a drastic reduction in time and resources from those required by past work, which relied on iterative 3D printing. The skull modeling process creates a footprint that is exported into modeling software to design custom-fit cranial chambers and headposts for surgical implantation. Custom-fit surgical implants minimize gaps between the implant and the skull that could introduce complications, including infection or decreased stability. By implementing these pre-surgical steps, surgical and experimental complications are reduced. These techniques can be adapted for other surgical processes, facilitating more efficient and effective experimental planning for researchers and, potentially, neurosurgeons.

Introduction

Nonhuman primates (NHPs) are invaluable models for translational medical research because they are evolutionarily and behaviorally similar to humans. NHPs have gained particular importance in neural engineering preclinical studies because their brains are highly relevant models of neural function and dysfunction^{1,2,3,4,5,6,7,8}. Some powerful brain stimulation and recording techniques, such as optogenetic....

Protocol

All procedures involving animals were approved by the Institute for Animal Care and Use Committee at the University of Washington. A total of four adult male rhesus macaques (Macaca mulatta) were used in this study. At the time of MRI acquisition, monkey H was 7 years old, monkey L was 6 years old, monkey C was 8.5 years old, and monkey B was 5.5 years old. Monkeys H and L were implanted with custom chronic chambers at 9 years of age.

1. Skull and brain isolation (

Discussion

This paper outlines a straightforward and precise method of neurosurgical planning that is not only beneficial for the development of components used for NHP cranial window implantation but also transferrable to other areas of NHP neuroscience research^13,15,25. In comparison to other current methods of NHP implant planning and design^{25,29,30<.......}

Materials

Name	Company	Catalog Number	Comments
3D Printing Software (Simplify 3D) (Paid)	Simplify3D	Version 4.1	Used for 3D printing using MakerGear printer
C-Clamp	Bessey	CM22	Used for artificial dura fabrication, 2-1/2 Inch Capacity, 1-3/8 Inch Throat
Formlabs Form 3+ 3D Printer	Formlabs	Form 3+	Used for precise 3D printing
MakerGear M2 3D Printer	MakerGear	M2 revG	Used for 3D printing implant prototypes
MATLAB (Paid)	MathWorks	R2021b	Used for brain and skull isolation, virtual craniotomy visualization and skull STL reduction
Phillips Acheiva MRI System	Philips	4522 991 19391	Used for non-human primate imaging
Photopolymer Resin	Formlabs	FLGPGR04	1L, Grey, used for precise 3D prints with Formlabs printer
PreForm Print Preparation Software	Formlabs	Version 2.17.0	Used for 3D printing with Formlabs printer
Printing Filament (PLA)	MatterHackers	88331	PLA 1.75 mm White. Used for 3D printing with MakerGear printer
Silicone CAT-1300	Shin-Etsu		Used for artificial dura fabrication
Silicone KE1300-T	Shin-Etsu		Used for artificial dura fabrication
SolidWorks (Paid)	Dassault Systems	2020	Used for chamber and headpost design
Syn.Flex-S Multicoil	Philips	45221318123	Used for non-human primate imaging