Table 1.

Averages of FA values of levels and levels

Reference FA valuesa (n)			Positive FA values(n)			Negative FA values(n)
Cauda equinas (n)	Left nerve roots (n)	Right nerve roots (n)	Cauda equinas (n)	Left nerve roots (n)	Right nerve roots (n)	Cauda equinas (n)	Left nerve roots (n)	Right nerve roots (n)
0.437 ± 0.028 (55)	0.457 ± 0.026 (55)	0.467 ± 0.026 (55)	0.295 ± 0.034 (99)	0.312 ± 0.034 (11)	0.310 ± 0.038 (18)	0.408 ± 0.045 (76)	0.484 ± 0.072 (76)	0.487 ± 0.055 (76)

^aAll levels were considered to be surgical decompression determined by conventional MRI; ^bthe reference FA values were taken by L1 levels in 54 patients, while in 1 patients, they were replaced by L2 levels because of the L1 levels were narrow; ^cAll the negative FA values were considered only nerve roots and/or cauda equinas in the negative levels, not that in the positive levels;d, If the FA value of lumbar cauda equina or/and the nerve root of the narrow level decreased ≥ 0.1 than the reference FA value, the level was positive; FA fractional anisotropy