Introduction of fast MR imaging in the assessment of hepatic steatosis

Abstract

We determined the utility of fast gradient echo techniques (modified Dixon method) in the assessment of hepatic fat content. Fast spoiled gradient echo was performed on bovine liver/corn oil homogenates with known fat fractions (FFE) to assess the accuracy of fat quantitation (FFMRI). The pulse sequence was manipulated via alterations in TE (echo time), TR (repetition time), and alpha (flip angle). In vivo studies were then performed using breath-holding maneuvers on normal adult volunteers and subjects at risk to develop hepatic steatosis, with cystic fibrosis or morbid obesity. At out-of-phase, TE, TR, and alpha were 2.1 ms, 7.3 ms, and 30-50 degrees and in-phase TE, TR, and alpha were 4.2 ms, 9.3 ms, and 30-50 degrees; FFMRI correlated well with FFE. An elevated fat fraction was observed in a high percentage of subjects with cystic fibrosis and morbid obesity. Fast gradient echo techniques were used successfully in the assessment of hepatic steatosis. The reduced acquisition times permitted in vivo analysis on adults and children using breath hold maneuvers.