Table 2.

Differences in imaging measures in the motor cortex between ALS (contralateral to the symptomatic limb) and control group (average of left and right). Results are from a multivariate GLM controlling for age and gender.

	ALS Mean (SD)	Control mean (SD)	F	p	Effect size (η2)	Required sample size for a t-test at 0.9 power
Non-diffusion measures
Motor cortex volume (mm3)	4.79 × 10−3 (3.08 × 10−4)	5.09 × 10−3 (4.72 × 10−4)	2.97	0.092	0.066	78
Blood flow (mL/100 g/min)	50.1 (9.6)	48.3 (10.2)	0.77	0.385	0.018	1276
Relative iron concentration	8.7 (7.9)	−12.5 (20.9)	5.24	0.030 ⁎	0.168	26
Primary diffusion/Kurtosis measures
Apparent diffusion/Kurtosis coefficient
ADC	8.44 × 10−4 (3.17 × 10−5)	8.33 × 10−4 (1.58 × 10−5)	3.89	0.055	0.085	220
AKC	0.953 (0.049)	0.988 (0.053)	10.03	0.003 ⁎⁎	0.193	46
Fractional anisotropy of diffusion/Kurtosis
FA	0.169 (0.010)	0.168 (0.017)	1.52	0.225	0.035	8178
FAK	0.149 (0.012)	0.140 (0.010)	3.61	0.064	0.079	66
Other diffusion/Kurtosis measures
Mean diffusivity/Kurtosis
MD	8.62 × 10−4 (2.06 × 10−4)	9.60 × 10−4 (2.04 × 10−4)	0.55	0.464	0.013	160
MK	0.744 (0.039)	0.775 (0.034)	12.28	0.001 ⁎⁎	0.226	76
Axial diffusivity/Kurtosis
AD	9.93 × 10−4 (3.94 × 10−5)	9.78 × 10−4 (1.69 × 10−5)	2.36	0.132	0.053	216
AK	0.674 (0.041)	0.706 (0.026)	16.29	<0.001 ⁎⁎	0.280	62
Radial diffusivity/Kurtosis
RD	7.69 × 10−4 (2.93 × 10−5)	7.61 × 10−4 (2.01 × 10−5)	3.88	0.056	0.085	516
RK	0.811 (0.038)	0.841 (0.040)	11.29	0.002 ⁎⁎	0.212	90

ALS, amyotrophic lateral sclerosis; ADC, apparent diffusion coefficient; AKC, apparent kurtosis coefficient; FA, fractional anisotropy of diffusion; FAK, fractional anisotropy of kurtosis; MD, mean diffusivity; MK, mean kurtosis; AD, axial diffusion; AK, axial kurtosis; RD, radial diffusion; RK, radial kurtosis; SD, standard deviation.

^⁎p < 0.05.

^⁎⁎p < 0.01.