Obesity and fat quantification in lean tissues using three-point Dixon MR imaging

Abstract

It has been suggested that increased hepatic and intramuscular fat is associated with insulin resistance, and that increased pancreatic fat is related to impaired insulin secretion. We postulated that in obese nondiabetic teenagers insulin levels would be directly related to increases in intramuscular and hepatic fat and inversely related to increases in pancreatic fat. MRI was used to assess the percentage of fat in the liver, muscle and pancreas in 15 healthy Mexican-American girls, 14-17 years old, with body mass indexes (BMIs) ranging from 17.7 kg/m(2) to 46 kg/m(2). Strong correlations were observed between BMI and fat content in the liver, muscle, and pancreas (r(2)s between 0.50 and 0.89; P<0.003). Serum insulin levels were closely associated with fat measures in the muscle and liver (r(2s)=0.63 and 0.29, and P=0.001 and P=0.023, respectively). In contrast to our hypothesis, fat content in the pancreas was also directly related to insulin secretion (r(2)=0.74; P=0.001). We conclude that in nondiabetic teenagers, obesity is associated with an increased accumulation of fat in the pancreas without impairment of insulin secretion.