Fig. 2From: A novel MRI index for paraspinal muscle fatty infiltration: reliability and relation to pain and disability in lumbar spinal stenosis: results from a multicentre studyAxial T2-weighted magnetic resonance image obtained at the level of the upper endplate of L3. The muscle fat index (MFI) was calculated by dividing the mean signal intensity of the psoas major (PM) with the mean signal intensity of the erector spinae (ES) and the multifidus (MF) musclesBack to article page