Adipose tissue R2*signal is increased in subjects with obesity: A preliminary MRI study

Objective: Circulating and adipose tissue markers of iron overload are increased in subjects with obesity. The aim is to study iron signals in adipose tissue. Methods: Adipose tissue R2* values and hepatic iron concentration (HIC) were evaluated using magnetic resonance imaging (MRI) in 23 middle-aged subjects with obesity and 20 subjects without obesity. Results: Subcutaneous (SAT) and visceral adipose tissue (VAT) R2* were increased in subjects with obesity (P=0.004 and P=0.008) and correlated significantly and positively with HIC in all subjects. Strikingly, most of the associations of liver iron with metabolic parameters were replicated with SAT and VAT R2*. BMI, waist circumference, fat mass, HOMA value, and C-reactive protein positively correlated with HIC and SAT and VAT R2*. BMI or percent fat mass (but not insulin resistance) contributed independently to 26.8-34.8% of the variance in sex- and age-adjusted SAT or VAT R2* (>0.40, P<0.005). Within subjects with obesity, total cholesterol independently contributed to 14.8% of sex- and age-adjusted VAT iron variance (=0.50, P=0.025). Conclusions: Increased R2* in adipose tissue, which might indicate iron content, runs in parallel to liver iron stores of subjects with obesity. VAT iron seems also associated with serum cholesterol within subjects with obesity.