Magnetic Resonance Spectroscopy (MRS) Validation Study in Individuals With Nonalcoholic Fatty Liver Disease (NAFLD)

• The Reproducibility of the Hepatic Triglyceride Content Measurement by MRS. [ Time Frame: 6 months ] [ Designated as safety issue: No ]
  We compared three 1H-Magnetic Resonance Spectroscopy sequences: A Standard Siemens sequence, and an optimized sequence with either breath-holds or free-breathing. Repeat scans were done with the subject briefly removed from and returned to the scanner between scans. The results given are coefficients of variation of the triglyceride signal divided by the water signal.
  
  

• The Hepatic Triglyceride Content Pre- and Post-prandial. [ Time Frame: after a 12 hour fast and 2 hours post-prandial ] [ Designated as safety issue: No ]
  We compared the intrahepatic triglyceride content in subjects after a 12 hour fast and 2 hours after eating a high fat, high carbohydrate meal. The measure reported here is for the pre and post prandial results given as the ratio of triglyceride signal to water signal. After showing its reliability, we chose to use the results from the optimized breath-hold sequence.
  
  
• T2 (Spin-spin Relaxation Time) Ratios of Triglyceride/Water [ Time Frame: baseline cross-sectional measurements ] [ Designated as safety issue: No ]
  T2 (spin-spin relaxation time) ratios of triglyceride/water using optimized PRESS sequences
  
  

One way to gauge MRS as an effective diagnostic tool is by looking at the reproducibility of the liver fat measurements on subjects by calculating the coefficient of variation (CV). This study assesses the modified MRS sequence, using both breath holds and free breathing. The HTGC levels are measured twice in the same individuals on two independent events separated by 10 minutes. Subjects are then given a high fat, high carbohydrate meal of Pizza Hut pizza, Pepsi, and Oreo cookies. Two hours after eating the meal, the subjects return to the scanner and repeat all MRS scans.