# Systematic evaluation of adhesives for implant fixation in multimodal functional brain MRI

## TL;DR

This study evaluates how different adhesives affect MRI image quality in rodents, finding that adhesive shape and field strength strongly influence artifacts.

## Contribution

The study introduces an integrative scoring system to evaluate adhesives for MRI, revealing that shape and volume are more critical than adhesive type for minimizing artifacts.

## Key findings

- Susceptibility artifacts were twice as large at 9.4 T compared to 7.0 T.
- Spherical adhesive patches caused deeper artifacts than flat patches.
- Resins, bonding agents, and acrylics performed best overall in the integrative scoring system.

## Abstract

Invasive multimodal fMRI in rodents is often compromised by susceptibility artifacts from adhesives used to secure cranial implants. We hypothesized that adhesive type, shape, and field strength significantly affect susceptibility artifacts, and systematically evaluated various adhesives.

Thirty-one adhesives were applied in constrained/unconstrained geometries and imaged with T2*-weighted EPI at 7.0 and 9.4 T to assess artifact depths. Spherical and flat patch shapes, both unconstrained geometries, were compared for artifact depth in vitro and in vivo. Adhesion strength was assessed on post-mortem mouse crania. Finally, an integrative scoring system rated adhesive properties, including artifact depth, handling, and adhesion strength.

Susceptibility artifacts were two times larger at 9.4 than at 7.0 T (p < 0.001), strongest at the patch edges, and deeper with spherical than flat patches (p < 0.05). Artifact size depended more on shape and volume after curing than adhesive type. Our integrative scoring system showed resins, bonding agents, and acrylics offered the best overall properties, while silicones and cements were less favorable.

Adhesive selection requires balancing handling, curing time, strength, and artifact depth. To minimize artifacts, adhesives should be applied in a spread-out, flat and thin layer. Our integrative scoring system supports classification of future classes of adhesives.

The online version contains supplementary material available at 10.1007/s10334-024-01220-4.