TABLE 2.

Comparison of different imaging parameters of FI

Indicator	Suggested application	Disadvantage
Semiquantitative grading	Intuitive and suitable for clinical evaluation among elderly patients; correlated with functional status and clinical outcomes	The cut‐off value is uncertain and the measurement error of people with slight FI is relatively large
Fat CSA/total CSA	Quantitative parameters based on area; correlated with multiple lumbar degenerative diseases	Requires threshold method
Fat volume/muscle volume	Quantitative parameters based on volume; reflects the overall situation of muscles	Requires three‐dimensional reconstruction
MFI	Quantitative parameters based on signal intensity; correlated with clinical outcomes	The reference of fatty signal intensity in MFI was diverse
Mean MRI signal intensity		Can be influenced by individuals and measurement tools

CSA, cross‐sectional area; FI, fat infiltration; MFI, muscle–fat index.