Table 1.

Five-point grading score for assessment of ¹⁸F–FDG-PET/CT and MRI in suspected vertebral osteomyelitis

	18F–FDG-PET/CT	MRI
Score 0a	Normal findings and physiological 18F–FDG distribution	Normal findings except for degeneration
Score 1a	Minimal increased 18F–FDG uptake compared to normal bone marrow 18F–FDG uptake	Minimal decreased SI T1 and increased SI T2 and enhancement in intervertebral or paravertebral region compared to normal bone marrow
Score 2Ab	Increased 18F–FDG uptake with a linear or disciform pattern in intervertebral disc space	Decreased SI T1 and increased SI T2 and enhancement with linear or disciform pattern at intervertebral disc space
Score 2Bb	Increased 18F–FDG uptake in only ossal structures without pathological changes in intervertebral discs	Decreased SI T1 and increased SI T2 and enhancement in only ossal structures, without changes in intervertebral discs
Score 3c	Increased 18F–FDG uptake with a linear or disciform pattern in intervertebral disc space and involvement of endplate (or adjacent vertebrae)	Decreased SI T1 and increased SI T2 at intervertebral disc space and involvement of endplate (or adjacent vertebrae)
Score 4c	Increased 18F–FDG uptake with a linear or disciform pattern in intervertebral disc space and involvement of endplate with surrounding soft tissue abscesses	Decreased SI T1 and increased SI T2 at intervertebral disc space and involvement of endplate with surrounding soft tissue abscesses.

^aScore 0 and 1 were considered as normal or aspecific and excluded vertebral osteomyelitis

^bScore 2A was considered as discitis and score 2B as osteomyelitis (without discitis)

^cScore 3 and 4 were considered as vertebral osteomyelitis