Table 3.

Imaging Biomarkers of Axonal Recovery

Imaging Biomarker	Lesions with FA Recovery (n=2)	Lesions without FA Recovery (n=9)	P Value
Acute FLAIR+	2/2 (100%)	5/9 (56%)	0.49
Acute GRE+	1/2 (50%)	2/9 (22%)	0.49
Acute FA	0.43 +/− 0.21	0.54 +/− 0.14	0.34
ΔFA	+0.15 [0.07 to 0.24]	−0.05 [−0.02 to −0.19]	--
Acute ADC	0.75 +/− 0.29	0.73 +/− 0.17	0.92
ΔADC	−0.02 [−0.16 to +0.12]	+0.28 [+0.10 to +0.48]	0.70
Acute AD	1.09 +/− 0.21	1.21 +/− 0.22	0.53
ΔAD	+0.18 [+0.07 to +0.29]	+0.30 [−0.02 to +0.60]	0.45
Acute RD	0.58 +/− 0.32	0.50 +/− 0.18	0.62
ΔRD	−0.11 [−0.25 to +0.02]	+0.27 [+0.09 to +0.56]	0.02

None of the acute imaging biomarkers were associated with FA recovery within traumatic axonal injury (TAI) lesions. Changes (Δ) in diffusion biomarkers are presented as mean change from the subacute to acute DTI scan [range]. Continuous variables (FA, ADC, AD, and RD) were compared in the TAI lesions with and without recovery using a T-test, and categorical variables (FLAIR+, GRE+) were compared using Fisher’s exact test. Abbreviations: “+” indicates that a lesion was visible; AD = axial diffusivity (x10⁻³ mm²/s); ADC = apparent diffusion coefficient (x10⁻³ mm²/s); FA = fractional anisotropy; FLAIR = T2-weighed fluid-attenuated inversion recovery sequence; GRE = T2*-weighted gradient-recalled echo sequence; RD = radial diffusivity (x10⁻³ mm²/s).