Traumatic Cerebral Microbleeds in the Subacute Phase Are Practical and Early Predictors of Abnormality of the Normal-Appearing White Matter in the Chronic Phase

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FIGURE.
Study design and research questions. Images are oblique coronal sections of the Montreal Neurological Institute brain, illustrating the regions evaluated for each research question (image plane illustrated in the thumbnail image in the right lower corner). ^aNumber of microbleeds per cm³ brain tissue. ^bZ-score of mean diffusivity. t1 indicates Moment of SWI-acquisition, i.e. 3 (2–5) weeks after TBI; t2, Moment of DTI-acquisition, i.e. 26 (25–28) weeks after TBI; MARS atlas, Microbleed Anatomical Rating Scale atlas²⁷; ICBM-DTI-81 atlas, the ICBM-DTI-81 white matter labels atlas designed by Mori S et al.²⁸

Association between microbleed concentrations at t1 and MD_z at t2

Research Question	Region of Microbleed Concentration	White Matter Region of MD Measurement	Univariable		Multivariable^{^a}
Research Question	Region of Microbleed Concentration	White Matter Region of MD Measurement	B_cmb-conc (95% CI, P)	B_cmb-nr (95% CI)	B_cmb-conc (95% CI, P)	B_cmb-nr (95% CI)
1.a	Cerebral hemispheres:	Cerebral hemispheres:
	Left	Left	35.2 (8.6–61.8, .011)	0.067 (0.016–0.117)	38.4 (7.5–69.3, .017)	0.073 (0.014–0.131)
	Right	Right	28.3 (11.1–45.5, .002)	0.055 (0.022–0.089)	26.3 (5.7–47.0, .014)	0.051 (0.011–0.091)
1.b	Central brain region	Central brain region	8.2 (−8.5–24.9, .322)	0.024 (−0.025–0.074)	7.8 (−9.9–25.6, .374)	0.023 (−0.029–0.076)
2.a	Structures connected through the corpus callosum	Corpus callosum	44.2 (23.6–64.8, .000)	0.041 (0.022–0.060)	20.0 (24.8–75.2, .000)	0.019 (0.023–0.070)
2.b	Cerebral hemispheres	Central brain region	24.2 (6.8–41.5, .008)	0.024 (0.007–0.040)	25.7 (3.9–47.5, .023)	0.025 (0.004–0.046)

Note:–Results of linear regression analyses. None of the variables other than microbleed concentration is associated with MD_z with P < .05 in the multivariable analyses.
↵a Multivariable linear regression analyses with the following independent variables: microbleed concentration, sex, age at the day of DTI imaging (years), and time passed from TBI to DTI acquisition (weeks). MD_z indicates Z-score of mean diffusivity; t1, 3 (2–5) weeks after trauma; t2, 26 (25–28) weeks after trauma; B_cmb-conc, linear regression coefficient with microbleed-concentration as independent variable; B_cmb-nr, linear regression coefficient with number of microbleeds as independent variable.