Table 2.

MRI outcomes (Dutch cohort).

	Ratio	p-value	95% confidence interval
			Low bound	Upper bound
T2 lesion volumes	2.13	0.03	1.08	4.18
G+-enhanced lesions	1.69	0.23	0.71	4.02
Black hole lesion volumes	0.93	0.85	0.44	1.96
Normalized brain volumes	0.42	0.02	0.24	0.90

MRI: magnetic resonance imaging; mtDNA: mitochondrial DNA; IQR: interquartile range; BHLV: black hole lesion volumes; NBV: normalized brain volumes.

The concentration of mtDNA copies was not normally distributed and therefore a natural logarithm was taken. For correlation analyses, subjects were divided into different groups according to their lesion volumes and normal brain volumes based on a median split. Using log transformation of the regression coefficients, ratios of the mitochondrial DNA concentrations between the different subgroups were calculated. Analyzing T2 lesion volumes, patients with higher T2 lesion volumes showed 2.13 times higher concentrations of mtDNA copies (p = 0.03). Patients with higher normalized brain volumes showed significant 0.42 times lower concentrations of mtDNA (p = 0.02).

T2 lesion volumes. Comparing group 2 with group 1. Group 1: median T2 lesion volume of 1.53 (IQR, 0.13–4.30) mL. Group 2: median T2 lesion volume of 10.53 (IQR 6.55–16.96) mL. Adjusted for disease duration.

Gadolinium-enhanced lesions. Comparing the group with the presence of gadolinium-enhanced lesions with the group with the absence of gadolinium-enhanced lesions. Adjusted for disease duration.

Black hole lesion volumes. Comparing group 2 with group 1. Group 1: median BHLV volume of 0.063 (IQR, 0.03–0.12) mL. Group 2: a median BHLV of 0.89 (IQR, 0.38–2.34) mL. Adjusted for disease duration.

Normalized brain volumes. Comparing group 2 with group 1. Group 1: median NBV 1.14 (1.09–1.18) L. Group 2: median NBV 1.29 (IQR, 1.22–1.33) L. Adjusted for disease duration and gender.