Twenty-five patients with hepatic
steatosis (alcoholic or non-alcoholic) diagnosed by histopathology
after biopsy will be submitted to a MRS examination as well as to DWI
and DEI exams. Urine and blood samples will be
collected beforehand in order to
perform bioassays and metabonomics studies.
healthy volunteers will be recruited to optimize the MR techniques. Twnty-five
healthy subjects will undergo the same MR tests as the patients.
metabonomics: The ALT and AST activities, the lipidic profile as well as
other biochemical parameters will be measured on the blood sample.
NMR spectra of urine and blood extracts will be recorded at high field for metabonomics.
MRS/MRI exams: Three MR examinations will be carried out at a
magnetic field of 1.5 T. All acquisitions will be performed with breathholding. Total exam duration
be approximately 30 minutes.
Spectroscopy (MRS): MR spectra will be recorded in three different
8 cc voxels (superior lobe, middle and inferior lobe of the liver). Spectra
will be treated and analyzed by the LCModel software to obtain the
Imaging (DWI): Diffusion-weighted images will be obtained on
axial sections covering all the liver. The apparent diffusion
coefficient (ADC) of water will be calculated in various areas using
DWI images example of the liver (located
in the left part of each images). The left image is a T2
where no gradient is
applied. The right image contains a
gradient with a value of b = 100
DWI is used to measure the passive water movement in an organ.
(DEI): Two series of images will be acquired, where the protons
are in phase and out of
phase respectively, on 16
axial slices. The Dixon method will be used to calculate the
fraction of fat present within the liver as well as the steatosis index.
DEI images of the liver. The left and right images are acquired with a gradient
that aligns all the protons in the same direction (in phase) and in opposite directions (out of phase), respectively . The fat fraction is calculated from these images.