MCQ — Radiology —- hepatic steatosis

 

All are true regarding role of MRI inhepatic steatosis except

1.liver appear bright in opposed phase of chemical shift  imaging (CSI)

2.MRI -PDFF has better accuracy than double echo CSI for fat quantification 

3.MRI - PDFF can assess the fat content of entire liver in short breath hold

4.MRI- PDFF has high accuracy in assessing hepatic steatosis

Ans —- 1

Liver appear dark in opposed phase of chemical imaging

Evaluation of fat with magnetic resonance imaging (MRI) is common by chemical-shift imaging (CSI)principal, where MRI detect different resonance frequencies between protons bound to water and fat. In a regular MRI sequence, images in “in-phase (IP)” and “opposed phase (OP)” are produced at specific echo times when water and fat signals are added and subtracted. This can produce a qualitative or semi-quantitative assessment of hepatic steatosis. In the presence of fatty liver, the liver will appear dark in opposed phase due to signal loss. 

Subsequently, dual-echo CSI was developed for fat quantifi- cation based on a pair of OP and IP images, but there were biased from T1- and T2*-relaxation effects. To improve accu- racy, T1-independent, T2*-corrected proton density fat frac- tion (PDFF) methods were developed based on multiple-echo CSI that acquire three or more consecutives pairs of OP and IP echoes.

MRI-PDFF method can assess the fat content of the entire liver in a short breath-hold, in about 20 s. The MRI-PDFF technique has high accuracy in evaluating liver steatosis. The AUROC for diagnosing hepatic steatosis ≥ 5% with his- tology as reference standard has been reported to be 0.98 in a recent meta-analysis