MR detection of brain iron

Area of Science:

• Neuroimaging
• Neurochemistry
• Aging Research

Background:

• Brain iron accumulation is known to increase with age.
• Iron's paramagnetic properties can affect magnetic resonance imaging (MRI) relaxation times, specifically T2 shortening.
• Previous studies have suggested a link between brain iron and T2 values, but quantitative data across different age groups and brain regions are needed.

Purpose of the Study:

• To quantitatively investigate the relationship between regional brain iron concentration and T2 relaxation time shortening in individuals from newborn to 35 years old.
• To determine if age-related increases in brain iron correlate with decreased T2 values in specific brain regions.

Main Methods:

• Quantitative T2 calculations were performed on T2-weighted spin-echo images from 60 patients (newborn to 35 years) across eight brain regions.
• Brain iron concentrations were measured in six regions from 13 autopsied brains (newborn to 78 years) using acid digestion and spectrophotometry.
• In vitro phantom studies were conducted to assess the effect of iron concentration on T2 values.

Main Results:

• All eight brain regions showed a decrease in T2 values with age, most notably in the substantia nigra during the first three decades.
• Five of the six measured brain regions exhibited an age-related increase in iron concentration.
• In vitro studies demonstrated that both ferric and ferrous iron phantoms showed decreased T2 values, with ferric iron causing more pronounced T2 shortening.

Conclusions:

• There is an age-related accumulation of iron in five brain regions, which correlates with a decrease in T2 values.
• Brain iron concentration appears to be a contributing factor to the progressive decrease in T2 signal observed with aging.