Table 1:

Grading of facet joint inflammation using fat-saturated MRI signal characteristics^{^a}

Grade
0	No signal abnormality
1	Signal abnormality limited to joint capsule
2	Periarticular signal abnormality involving <50% of the facet joint perimeter^{^b}
3	Periarticular signal abnormality involving >50% of the facet joint perimeter
4	Grade 3 with additional signal abnormality within the neural foramen, pedicle, ligamentum flavum, transverse process, or vertebral body^{^c}

↵a Grading scale adapted from Czervionke and Fenton.⁶
↵b Periarticular signal abnormality includes T2 hyperintensity or gadolinium enhancement on T1-weighted images.
↵c Signal abnormality within the pedicle must be continuous with other perifacet signal abnormalities and cannot represent posterior extension of vertebral body edema.