Aims and objectives
Thequantification of hepatic steatosis in recent years showed a great improvement,
especially by magnetic resonance imaging (MRI),
initially by the use ofspectroscopy techniques and finally with proton densityfat fraction(PDFF) sequence.
This last technique allows the creation of a fat map,
with correction of several factors,
making it extremely easy and reliable to evaluate steatosis from pixel to pixel. Among the main corrections of the PDFFanalysis are the T1 and T2* relaxation.
Methods and materials
A total of 102 patients with NASH diagnosed by percutaneous biopsy were analyzed.
Patients underwent a dedicated MRI study on a 3T device (Phillips Achieva) with a surface coil,
less than 6 months after the biopsy.
14 volunteers with no history of liver disease and normal laboratory tests for hepatic function were also included. The assessment of iron and fat deposition in the liver was made through a multi- spoiled gradient echo sequence (MSGE),
where magnitude data were acquired.
The mean FF value was 14.4% (SD = 9.2 / Min = 4.1% / Max = 54.8%).
There was a good correlation between the degree of steatosis and the FF by the PDFF method,
estimated in 0.72.
The cut-off value considered ideal for steatosis was 5.4% with AROC of .98 for the distinction between normal and fat liver patients (Fig 4). The mean value of R2* was 67.5 s -1 (SD = 42 / Min = 34.5 s -1 / Max = 384 s -1 ).
The ideal cutoff value for detection of siderosis (in correlation with histology) was 68.8 s...
The FF estimated from PDFF is very similar to the 3D Dixon technique in this group of NASH patients evaluated in a 3T machine. The Correlation Coefficient between the techniques is only lower when the R2* is >69.9 s -1 . This work shows the possibility of using conventional 3D Dixon techniques in steatosis quantification in patients without signs of iron deposition.
Quantitative MR Imaging of Hepatic Steatosis: Validation in Ex Vivo Human Livers.
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2010 Aug;18(3):337–57–ix. Hines CDG,
T2* corrected chemical shift based fat-water separation with multi-peak...