Characteristic distributions of intracerebral hemorrhage-associated diffusion-weighted lesions

Abstract

Objectives: To determine whether small diffusion-weighted imaging (DWI) lesions occur beyond the acute posthemorrhage time window in patients with intracerebral hemorrhage (ICH) and to characterize their spatial distribution in patients with lobar and deep cerebral hemorrhages.

Methods: In this cross-sectional study, we retrospectively analyzed 458 MRI scans obtained in the acute (≤ 7 days after ICH) or nonacute (>14 days after ICH) phases from 392 subjects with strictly lobar (n = 276) and deep (n = 116) ICH (48.7% women; mean age 72.8 ± 11.7 years). DWI, apparent diffusion coefficient maps, fluid-attenuated inversion recovery, and T2* MRIs were reviewed for the presence and location of DWI lesions.

Results: We identified 103 DWI hyperintense lesions on scans from 62 subjects, located mostly in lobar brain regions (90 of 103, 87.4%). The lesions were not uniformly distributed throughout the brain lobes; patients with strictly lobar ICH had relative overrepresentation of lesions in frontal lobe, and patients with deep ICH in parietal lobe (p = 0.002). Although the frequency of DWI lesions tended to be greater on scans performed within 7 days after ICH (39 of 214, 18.2%), they continued at high frequency in the nonacute period as well (23 of 178, 12.9%, odds ratio 1.5, 95% confidence interval 0.86-2.6 for acute vs nonacute). There was also no difference in frequency of lesions on acute and nonacute scans among 66 subjects with MRIs in both time periods (8 of 66 acute, 10 of 66 nonacute, odds ratio 0.77, 95% confidence interval 0.25-2.4).

Conclusions: The high frequency of DWI lesions beyond the acute post-ICH period and their characteristic distributions suggest that they are products of the small vessel diseases that underlie ICH.

Figure 1. DWI lesions in acute and nonacute time periods

Shown are a parietal DWI lesion seen 1 day after contralateral basal ganglia hemorrhage in a 66-year-old man (A) and a frontal DWI lesion 2 years after contralateral parietal hemorrhage in a 69-year-old man (B). DWI = diffusion-weighted imaging.

Figure 2. DWI lesion distribution within brain tissue

The 6 axial 10-mm slabs demonstrate the distribution of 82 of the 103 DWI lesions; the remaining 21 lesions were located in the other 9 slabs not shown in the figure. In each image, all lesions within a slab are overlaid onto the middle slice of the slab. Lesion markers were placed at the center of the marked lesion after image resampling and do not represent the actual size of the lesion. DWI = diffusion-weighted imaging; ICH = intracerebral hemorrhage.

Figure 3. Three-dimensional map of DWI lesion distribution

The axial (A, C) and sagittal (B, D) images display the composite locations of the acute and nonacute DWI lesions in the lobar and deep ICH groups. Each spot represents the center of the lesion. DWI = diffusion-weighted imaging; ICH = intracerebral hemorrhage.