# Orthodontic appliances and their diagnostic impact to brain MRI

## TL;DR

This study examines how different orthodontic appliances affect brain MRI quality and finds that most can remain during scans without reducing diagnostic quality.

## Contribution

The study quantifies MRI artifacts caused by various orthodontic appliances and suggests selective removal of only problematic components.

## Key findings

- Conventional orthodontic appliances allow high diagnostic quality in brain MRI at both 1.5T and 3T.
- Trans-palatal stainless-steel archwires cause significant artifacts in SWI and DWI sequences.
- Removing only the trans-palatal archwire can maintain diagnostic quality while reducing risks and saving time.

## Abstract

The aim of this study was to display and quantify signal loss artifacts in 1.5T and 3T brain MRI on a volunteer with different orthodontic appliances.

In this experimental study, three different orthodontic appliances were examined on a 1.5T and a 3T MRI scanner in a healthy adult with normal dental occlusion: stainless-steel brackets paired with a nickel-titanium archwire; brackets, archwire, and stainless-steel molar bands; brackets, archwire, molar bands, and a stainless-steel trans-palatal archwire. Assessment of diverse anatomical structures, including different cerebral structures and blood vessels, was conducted using a six-point Likert scale.

Utilizing conventional stainless-steel brackets and a nickel-titanium archwire, with or without the inclusion of stainless-steel molar bands, all cerebral structures demonstrated satisfactory assessability with high diagnostic quality under both 1.5T and 3T MRI. For example, with an average rating of 85/85 for T2 and 77/85 for susceptibility-weighted imaging (SWI). Upon introduction of the stainless-steel trans-palatal archwire, additional artifacts were observed, predominantly manifesting in SWI (20/85), diffusion-weighted imaging (DWI) sequences (31/85), and phase contrast angiography (PCA) (17/20). Differences in artifact severity were mainly observed in the SWI and DWI sequences.

Based on the findings of this study, it is not imperative to entirely remove orthodontic appliances to achieve sufficient diagnostic quality in brain MRI. In instances where SWI or DWI sequences are necessitated, the removal of solely the trans-palatal stainless-steel archwire should be contemplated, given its straightforward execution.

These results highlight the potential to reduce injury risk during orthodontic appliance removal, expedite imaging procedures, and consequently accelerate diagnostic processes, particularly crucial in emergencies.