Temporal and Spatial Clustering of Intracerebral Hemorrhage in Cerebral Amyloid Angiopathy.

OBJECTIVES: Cerebral amyloid angiopathy (CAA)-associated lobar intracerebral hemorrhage (ICH) has a high risk of recurrence, but the underlying mechanisms remain uncertain. We, therefore, aimed to characterize patterns of recurrent ICH. METHODS: We investigated early recurrent ICH (≥1 recurrent ICH event within 90 days of the index event) and ICH clusters (≥2 ICH events within 90 days at any time point) in 2 large cohorts of consecutive patients with first-ever ICH and available MRI. RESULTS: In 682 included patients (median age 68 years, 40.3% female, median follow-up time 4.1 years), 18 (2.6%) had an early recurrent ICH, which was associated with higher age and CAA. In patients with probable CAA, the risk of early recurrent ICH was increased 5-fold within the first 3 months compared with during months 4-12 (hazard ratio 5.41, 95% CI 2.18-13.4) while no significant difference was observed in patients without CAA. In patients with an ICH cluster, we observed spatial clustering (recurrent ICH within close proximity of index ICH in 63.0%) and a tendency for multiple sequential hemorrhages (≥3 ICH foci within 3 months in 44.4%). DISCUSSION: Our data provide evidence of both temporal and spatial clustering of ICH in CAA, suggesting a transient and localized active bleeding-prone process.

Low-frequency MR elastography reveals altered deep gray matter viscoelasticity in multiple sclerosis.

INTRODUCTION: Brain viscoelasticity as assessed by magnetic resonance elastography (MRE) has been discussed as a promising surrogate of microstructural alterations due to neurodegenerative processes. Existing studies indicate that multiple sclerosis (MS) is associated with a global reduction in brain stiffness. However, no study to date systematically investigated the MS-related characteristics of brain viscoelasticity separately in normal-appearing white matter (NAWM), deep gray matter (DGM) and T2-hyperintense white matter (WM) lesions. METHODS: 70 MS patients and 42 healthy volunteers underwent whole-cerebral MRE using a stimulated echo sequence (DENSE) with a low-frequency mechanical excitation at 20 Hertz. The magnitude |G∗| (Pa) and phase angle φ (rad) of the complex shear modulus G∗ were reconstructed by multifrequency dual elasto-visco (MDEV) inversion and related to structural imaging and clinical parameters. RESULTS: We observed φ in the thalamus to be higher by 4.3 % in patients relative to healthy controls (1.11 ± 0.07 vs. 1.06 ± 0.07, p < 0.0001). Higher Expanded Disability Status Scale (EDSS) scores were negatively associated with φ in the basal ganglia (p = 0.01). We measured φ to be lower in MS lesions compared to surrounding NAWM (p = 0.001), which was most prominent for lesions in the temporal lobe (1.01 ± 0.22 vs. 1.06 ± 0.19, p = 0.003). Age was associated with lower values of |G∗| (p = 0.04) and φ (p = 0.004) in the thalamus of patients. No alteration in NAWM stiffness relative to WM in healthy controls was observed. CONCLUSION: Low-frequency elastography in MS patients reveals age-independent alterations in the viscoelasticity of deep gray matter at early stages of disease.