# Cerebral iron deposition in the Globus pallidus and Substantia nigra of aging dogs and cats presenting as bilateral hypointensity on T2w and iron-sensitive MRI sequences (SWI, T2*)

## TL;DR

The study found that aging dogs show increased brain iron deposits detectable via MRI, with visibility influenced by age and MRI field strength.

## Contribution

The study identifies age and MRI field strength as significant factors in detecting cerebral iron accumulation in aging dogs using advanced MRI sequences.

## Key findings

- Age is a significant predictor of cerebral iron deposit visibility in dogs.
- Higher MRI field strengths (1.5T and 3T) improve visibility of iron deposits compared to 1T in dogs.
- Iron-sensitive sequences (SWI, T2*) outperform T2w in detecting iron deposits in canines.

## Abstract

With aging, dysregulation of brain iron homeostasis can lead to cerebral iron accumulation, a process associated with the pathogenesis of neurodegenerative diseases and recognized as an imaging marker in humans. Similarly, MRI-detected cerebral iron accumulation has been reported in aging beagles, suggesting parallels with human findings.

Single-center, observational study that retrospectively and prospectively evaluated 236 client-owned animals (198 dogs, 38 cats) undergoing brain MRI between 2014 and 2024. Patients represented various breeds and ages; scans were performed at different field strengths, 1-3 Tesla (T), with each animal examined once at a single field strength. MRIs were evaluated for bilateral hypointensities in T2-weighted (T2w) and iron-sensitive imaging (SWI, T2*) in the Globus pallidus and Substantia nigra. In selected cases, iron deposition was validated via post-mortem iron-sensitive Perl’s staining of fixed brain tissues.

Logistic regression analysis identified age as a significant predictor of improved visibility (OR = 1.21, p < 0.0001). Compared with 1T, 1.5T increased the odds of visibility by 2.78-fold (p = 0.0366), and 3T by 4.82-fold (p < 0.001). Species-specific analysis showed that, in cats, field strength had no significant effect (p = 0.1575), whereas age remained a significant predictor (p = 0.0192). Iron-sensitive sequences (SWI, T2*) provided superior visibility of iron deposits compared to T2w, particularly in dogs. No significant difference in hypointensity detection was observed between the two brain regions.

In summary, age and MRI field strength significantly affect the visibility of cerebral iron deposits in dogs, whereas feline results require further investigation due to the limited sample size. SWI and T2* enhance iron detection compared to T2w, particularly in canines.