Quantification of MRI-PDFF by complex-based MRI: phantom and rabbit study at 3.0T

This paper aimed to evaluate the accuracy of magnetic resonance imaging-proton density fat fraction (MRI-PDFF) in fat-water-iron phantom and rabbit with hepatic steatosis using complex-based chemical shift-encoded MRI technology. Phantoms of varying fat, water and iron content were constructed. Rabbit model with hepatic steatosis was successfully established by high-fat and high cholesterol diet. All MR examinations were performed on a 3.0T MR system. PDFF values of phantoms and rabbits were calculated from IDEAL-IQ. Fat assessment of rabbit liver biopsy was performed as reference standard. MRI-PDFF of four phantom groups with different iron content has no significant difference with the known fat contents (F=0.011, p=1.0), and extremely close correlations were observed (r=0.998, 0.998, 0.999, 0.998, respectively, all p<0.001). The existence of magnetic microspheres in phantoms did not affect fat measurement accuracy. MRI-PDFF showed significant differences between different steatosis grades with medians of 3.72% (normal), 5.43% (mild), 9.11% (moderate) and 11.17% (severe) except normal with mild steatosis. Close correlation between MRI-PDFF and histological steatosis was observed (r=0.78, p<0.01). IDEAL-IQ provides robust and promising fat quantification and can be considered potential alternative to biopsy for chronic patients where available.